A Brief Journey into the History of and Future Sources and Uses of Fatty Acids

We hypothesized that the polyunsaturated fatty acids of the butterfly were probably derived from the diet and that there might be a great loss of body fat during metamorphosis. To substantiate these hypotheses, we analyzed the fatty acid composition and content of the diet, the larva, and the butterfly Morpho peleides. Both the diet and the tissues of the larva and butterfly had a high concentration of polyunsaturated fatty acids. In the diet, linolenic acid accounted for 19% and linoleic acid for 8% of total fatty acids. In the larva, almost 60% of the total fatty acids were polyunsaturated: linolenic acid predominated at 42% of total fatty acids, and linoleic acid was at 17%. In the butterfly, linolenic acid represented 36% and linoleic acid represented 11% of total fatty acids. The larva had a much higher total fatty acid content than the butterfly (20.2 vs. 6.9 mg). Our data indicate that the transformation from larva to butterfly during metamorphosis drastically decreased the total fatty acid content. There was bioenhancement of polyunsaturated fatty acids from the diet to the larva and butterfly. This polyunsaturation of membranes may have functional importance in providing membrane fluidity useful in flight.

Thioesterase activity is typically required for the release of products from polyketide synthase enzymes, but no such enzyme has been characterized in deep-sea bacteria associated with the production of polyunsaturated fatty acids. In this work, we have expressed and purified the Orf6 thioesterase from Photobacterium profundum. Enzyme assays revealed that Orf6 has a higher specific activity toward long-chain fatty acyl-CoA substrates (palmitoyl-CoA and eicosapentaenoyl-CoA) than toward short-chain or aromatic acyl-CoA substrates. We determined a high resolution (1.05 Å) structure of Orf6 that reveals a hotdog hydrolase fold arranged as a dimer of dimers. The putative active site of this structure is occupied by additional electron density not accounted for by the protein sequence, consistent with the presence of an elongated compound. A second crystal structure (1.40 Å) was obtained from a crystal that was grown in the presence of Mg(2+), which reveals the presence of a binding site for divalent cations at a crystal contact. The Mg(2+)-bound structure shows localized conformational changes (root mean square deviation of 1.63 Å), and its active site is unoccupied, suggesting a mechanism to open the active site for substrate entry or product release. These findings reveal a new thioesterase enzyme with a preference for long-chain CoA substrates in a deep-sea bacterium whose potential range of applications includes bioremediation and the production of biofuels.

Microbes can produce not only commodity fatty acids, such as palmitic acid (16:0) and stearic acid (18:0), but also high-value fatty acids (essential fatty acids). Most high value fatty acids belong to long chain polyunsaturated fatty acids (PUFA), such as omega-3 fatty acids (e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) and omega-6 fatty acids (e.g., arachidonic acid (ARA) and γ-linolenic acid (GLA)). EPA (20:5n-3) is a 20-carbon fatty acid with five double bonds, and the first double bond is in the n-3 position. DHA (22:6n-3) is a 22-carbon fatty acid with 6 double bonds and the first double bond is also in the n-3 position. Both EPA and DHA play an essential role in cardiovascular health including prevention of atherosclerotic disease development (Zehr and Walker, Prostaglandins Other Lipid Mediat 134:131-140, 2018). ARA (20:4n-6) is a 20-carbon fatty acid with four double bonds, and the first double bond is in the n-6 position. GLA (18:3n-6) is an 18-carbon fatty acid with three double bonds, and the first double bond is in the n-6 position. ARA and GLA have multiple biological effects, such as lowering blood cholesterol, and lowering cardiovascular mortality (Poli and Visioli, Eur J Lipid Sci Technol 117(11):1847-1852, 2015). This chapter provides details on microbial production of EAP, DHA, ARA, and GLA.

This study evaluates the growth and chemical composition of the following marine microalgae: Dunaliella tertiolecta, Isochrysis galbana, and Tetraselmis gracilis and the chemical composition of Chlorella pyrenoidosa. Microalgae can produce a number of compounds of high commercial value for the industry, mainly for the food industry. The growth kinetics, cell volume, pigments, carbohydrates, proteins, lipids, and fatty acid and amino acid composition were evaluated. I. galbana had the largest number of cells per mL-1 (107), concentration of carotenoids (6.33 μg·mL-1), and carbohydrates (34.32%). D. tertiolecta and T. gracilis had the highest cell volume (560.6 and 592.7 μm3, respectively), the highest amount of total dry biomass. D. tertiolecta had the highest chlorophyll concentration (9.05 μg·mL-1), and C. pyrenoidosa had the highest protein (48.16%) and lipid (14.30%) content. The marine species D. Tertiolecta, I. galbana, and T. gracilis had high levels of monounsaturated fatty acids (C18:1 n9), and C. pyrenoidosa was high in polyunsaturated fatty acids (C18:2 n6 and C18:3 n3), indicating the present high nutritional value fatty acids. The microalgae studies showed a composition of amino acids that meet the nutritional requirements recommended by the FAO g·100 g-1 (FAO/WHO/UN, 1985) for adults and children (2 - 5 years), indicating that these proteins can be used in foods.

Imbalanced fatty acid metabolism contributes significantly to the increased incidence of metabolic disorders. Isotope-labeled fatty acids (2H, 13C) provide efficient means to trace fatty acid metabolism in vivo. This study reports a new and rapid method for the quantification of deuterium-labeled fatty acids in plasma by HPLC-MS. The sample preparation protocol developed required only hydrolysis, neutralization, and quenching steps followed by high-performance liquid chromatography-electrospray ionization-mass spectrometry analysis in negative ion mode using single ion monitoring. Deuterium-labeled stearic acid (d7-C18:0) was synthesized to reduce matrix interference observed with d5 analog, which improved the limit of detection (LOD) significantly, depending on the products analyzed. Linearity > 0.999 between the LOD (100 nM) and 30 microM, accuracy > 90%, precision > 88%, and adequate recovery in the dynamic range were obtained for d7-C18:0 and d7-oleic acid (C18:1). Upon oral dosing of d7-C18:0 in rats, the parent compound and its desaturation and beta-oxidation products, d7-C18:1 and d7-C16:0, were circulating with a maximal concentration ranging from 0.6 to 2.2 microM, with significant levels of d7-fatty acids detected for up to 72 h.

Colon cancer, which is the fourth most common cancer in the world, is one of the leading causes of cancer death in both men and women in the United States, Canada, Northern and Western Europe, Australia and New Zealand.1, 2 It is markedly less frequent in Asia, Africa and South America.1, 2 Therefore, it is a major public health problem. Migrant and temporal trend studies suggest that colon cancer is determined largely by environmental exposures, especially nutritional habits.1 Marked international differences in the incidence and mortality of colon cancer and increase of risk in populations migrating from low- to high-risk areas such as from Japan, China and the Philippines to the United States within 1 or 2 generations suggest that environmental factors, specifically dietary habits, rather than the genetic factors play an important role in the etiology of this cancer. This upward trend in incidences of colon cancer among Japanese immigrants in Hawaii and California compared to Japanese in Japan stimulated epidemiologists to investigate the reasons for this increase. Although the relationship between nutrition and cancer is complex and sometimes perplexing to nutritionists and to those who visualize carcinogenesis in terms of a specific carcinogen, it should be recognized that nutritional factors and diet may relate to cancer risk in several ways; first, food additives, contaminants, a particular dietary component, or products formed during food preparation may act as carcinogens, cocarcinogens and/or promoters; second, nutrient deficiencies and excesses may lead to biochemical/molecular alterations that may promote neoplastic processes; third, changes in the intake of selected macronutrients may induce metabolic, biochemical and molecular abnormalities that enhance cancer risk; and fourth, certain dietary constituents act as anticarcinogens or chemopreventives. During the last 3 decades, substantial progress has been made in understanding the relationship between dietary constituents and colon cancer risk. Fish oils are unique because they contain high levels of polyunsaturated omega-3 fatty acids (n-3 PUFAs) that are not present in vegetable oils or in saturated fats. Omega-3 fatty acids that are present in fish oil include docosahexaenoic acid (DHA; C22:6), eicosapentaenoic acid (EPA; C20:5) and docosapentaenoic acid (DPA; C22:5). Vegetable oils including corn oil and safflower oil contain high levels of linoleic acid (LA; C18:2). LA has the terminal double-bond 6 carbon atoms from the terminal (omega) methyl group of fatty acid, whereas DHA has the terminal double-bond 3 carbon atoms from the terminal (omega) methyl group of fatty acid (Fig. 1). Chemical structures of omega-3 and omega-6 fatty acids. Nutritional epidemiologic studies have provided evidence that dietary factors are important determinants of colorectal cancer in different populations worldwide. Cancer statistics in Japan for 2001 published by the Foundation for Promotion of Cancer Research indicate that there is an upward trend in age-adjusted mortality rates for colon cancer from 1955 to 1999.3 According to this report, the death rates due to colon cancer in Japanese men and women in 1955 were 2.9 and 3.0, respectively, whereas they increased to 14.7 and 9.8 in 1999. This upward trend in death rates due to colon cancer is mainly attributable to Westernization of Japanese food habits.3, 4 In addition, the report by the Foundation for Promotion of Cancer Research provided the data on the time trends in food consumption, which show increased dietary intakes of animal fat and meat and decreased consumption of whole grains from 1960 to 1999. For example, animal fat consumption in 1960 was about 25 g/day (per capita), whereas in 1999 it increased to about 58 g/day. Meat intake was increased from 19 to 78 g/day (per capita), whereas grain consumption decreased from 453 to 245 g/day during these years.3 The importance of types of dietary fat differing in fatty acid composition rather than total fat cannot be discounted because several preclinical studies using well-established colon cancer models strongly supported the notion that the colon tumor-promoting effect of dietary fat or lack of such effect depends on its fatty acid composition.5 A recent report by an expert panel assembled by the American Institute for Cancer Research/World Cancer Research Fund came to the scientific consensus that evidence for an association between the intake of saturated fat and/or animal fat and colon cancer risk is very strong.6 Continuing population studies revealed that diets particularly high in total fat, especially animal fat, are generally associated with increased risk of developing colon cancer, whereas high dietary fish oil or fish reduces this risk.7, 8 A recent ecologic study suggests that mortality data for colorectal cancer in 22 European countries, the United States and Canada correlate with the consumption of animal fat.7 That eating a diet rich in n-3 PUFAs may decrease the risk of colorectal cancer has been hypothesized in relation to fish and fish oil.7 Caygill and Hill et al.8 reported an inverse correlation between fish and fish oil consumption and colorectal cancer when expressed as a proportion of total or animal fat. This inverse relationship was significant for both male and female colorectal cancer, whether the intakes were in the current period or 10 years or 23 years before cancer mortality, It is noteworthy that these effects were only observed in countries with a high (> 85 g/caput/day) animal fat intake.8 Also, Mediterranean diet rich in olive oil and fish is associated with a low risk of colorectal cancer.9 On the basis of epidemiologic evidence, it is reasonable to suggest that diets high in saturated fats increase the risk of colorectal cancer, whereas diets high in fish and fish oil rich in n-3 PUFAs reduce the risk. Animal models have contributed significantly to understanding of the carcinogenesis process and to study the multiple environmental factors against the pathogenesis of colon cancer.10 Several studies have utilized these relevant animal models to investigate the modulation of colon carcinogenesis by nutritional and chemopreventive agents. These animal models include induction of colon tumors in rats by administration of aromatic amines such as 3,2′-dimethyl-4-aminobi-phenyl (DMBA); derivatives and analogs of cycacin, such as methylazoxymethanol (MAM), 1,2-dimethyl-hydrazine (DMH) and azoxymethane (AOM) in rats and mice of selected strains; direct-acting carcinogens of the type of alkylureas, such as methylnitrosourea (MNU) or N-methyl-N′-nitro-N-nitrosoguanidine (MNNG); and heterocyclic amines such as 2-amino-3-methylimidazo [4,5-f] quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). The spectrum of epithelial lesions induced in the colon by these agents is similar to various types of neoplastic lesions observed in the colorectum of humans. Azoxymethane (AOM), which is a potent inducer of carcinomas of the large intestine in various strains of male and female rats, has been used extensively by many investigators to induce colon tumors and to study the effects of nutritional factors and chemopreventive agents in colon carcinogenesis.10, 11, 12, 13, 14, 15, 16, 17 Colons of Fischer (F344) rats treated with AOM seem to have light and electron microscopic morphology as well as histochemical properties that are quite similar to that of humans and the biologic behavior of AOM-induced rat colon carcinomas is similar to that of human colon carcinomas.10, 18 Other characteristics of the human disease process reflected in the AOM rat model are the occurrence of both adenomas and adenocarcinomas.18 Also, aberrant crypt foci (ACF), which are recognized as early appearing preneoplastic lesions, develop in experimentally induced colon carcinogenesis in laboratory rodents as well as in the colonic mucosa of patients with colon cancer.19, 20 Recently, β-catenin-accumulated crypts were identified in the colonic mucosa at the early stages of AOM-induced colon carcinogenesis and are considered as early-appearing preneoplastic lesions.21 Therefore, ACF are now regarded as putative preneoplastic lesions for colon cancers and are used as biomarkers to evaluate potential chemopreventive agents against colon carcinogenesis.22 AOM treatment also induces oncogene mutations at codon 12 of K- and H-ras and increases in the expression of the ras family of protooncogenes have been causally associated with colon tumor development.23, 24 Enhanced ras oncogene expression has been observed in a variety of human colon tumors.25 AOM-induced colon tumors also demonstrate enhanced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression similar to human colon tumors.13, 26 Mutations in the tumor suppressor gene, APC, are known to be early events in the colon cancer process in humans and have been identified in patients with familial adenomatous polyposis, who have germline mutation in one of the APC alleles, and in sporadic colorectal cancer.27, 28 Evidence in humans thus implicates the APC suppressor gene as causal in large bowel carcinogenesis. Recent studies indicating the presence of APC mutation in AOM-induced colon tumors in rats strengthens the concept that these models are appropriate for human colon cancer studies.29 It has been increasingly apparent that β-catenin signaling pathway is closely associated with the development of colon cancer.30 Also, frequent mutations in the β-catenin gene are confirmed in AOM-induced colon tumors in rodent models.30 Furthermore, it has recently been indicated that the expression of nuclear β-catenin is correlated with the size of colon neoplasms.31 Because of similarities of histopathology of adenomas and adenocarcinomas, ACF and several molecular parameters between human colon tumors and AOM-induced colon tumors, it is indicated that the AOM model system and other chemically induced colon models appear to be appropriate colon cancer models. Recent progress in the area of molecular carcinogenesis has identified multiple molecular targets for the chemoprevention and nutritional modulation of colon cancer. The multiple intestinal neoplasia (Min) mouse, which carries a fully penetrant dominant mutation converting codon 850 of the murine APC gene from a lucine to a stop codon, is markedly different from that of patients with familial adenomatous polyposis (FAP) in which adenomas are found exclusively in the colon and duodenum, whereas in Min mouse adenomas are detectable in the small intestine and rarely in the colon. APCΔ716 knockout mice also develop numerous intestinal polyps at an early age.32 These are potential limitations of APCMin mouse and knockout models for testing agents for their potential chemopreventive properties against colon carcinogenesis. The development of strategies for prevention of colorectal cancer by dietary modification has been markedly facilitated by the use of relevant laboratory animal models, including carcinogen-induced colon cancer mimicking the neoplastic process that occurs in humans. Ample and consistent experimental evidence from preclinical efficacy studies conducted earlier have provided convincing evidence that not only the amount but also types of dietary fat differing in fatty acid composition are important factors in determining modulating effect of this nutrient in colon tumor development.33, 34, 35, 36 Studies conducted in our laboratory and those of others have consistently demonstrated that diets high in beef tallow, lard and corn oil (20–23% in the diet) significantly increased chemically induced colon carcinogenesis in F344 and Sprague-Dawley rats as compared to diets low (5%) in these fats.11, 33, 34, 35, 36, 37, 38 Additional studies conducted in our laboratory also demonstrate that male F344 rats fed diets containing 20% lard or 20% corn oil rich in n-6 PUFAs were more susceptible to 1,2-dimethylhydrazine-induced colon carcinogenesis compared with those fed diets containing 5% lard or 5% corn oil.38 Deschner et al.39 demonstrated that dietary n-3 PUFAs (fish oil) inhibits methylazoxymethanol (metabolite of azoxymethane)-induced focal areas of dysplasia and colon tumors, whereas n-6 PUFAs (corn oil) enhance colon tumorigenesis in rats. In a recent study, Chang et al.11 reported a protective effect of dietary fish oil against AOM-induced colon carcinogenesis in male Sprague-Dawley rats. High dietary fish oil significantly inhibited colon tumors as compared to high corn oil diet. In addition, colon tumor inhibition by fish oil diet was associated with lower levels of DNA damage in the distal colon compared with corn oil diet.11, 40 These studies provided evidence in preclinical models that diets containing high amount of saturated fat of animal origin or n-6 PUFAs had a greater colon tumor-enhancing effect than diets low in such fatty acids, whereas diets high in n-3 PUFAs had no such enhancing effect Further studies in our laboratory have evaluated the modulating effects of high dietary corn oil and safflower oil rich in n-6 PUFAs, olive oil high in monounsaturated fatty acid oleic acid, coconut oil high in medium-chain fatty acids such as lauric acid and fish oil during the postinitiation stage of AOM-induced colon carcinogenesis in male F344 rats.14, 37, 38, 41 Animals fed diets containing high corn oil or safflower oil (23.5%) had a higher incidence of colon tumors than did those fed diets low in fat (5%). By contrast, diets high in coconut oil, olive oil or menhaden fish oil had no such colon tumor-enhancing effect. The varied effects of different types of fat on colon carcinogenesis during postinitiation stage suggest that fatty acid composition is one of the determining factors in colon tumor promotion by a dietary fat and that the influence of types and amount of dietary fat is exerted mostly during the postinitiation phase of carcinogenesis.34, 41, 42 In this connection, it is interesting to note that in a phase 2 clinical trial of patients with colonic polyps, dietary fish oil supplements have in fact inhibited cell proliferation in the colonic mucosa.43 Thus far, progress has been made with regard to the relationship between dietary fat intake and colon cancer risk in that we know of the tumor-promoting effects of diets rich in n-6 PUFAs and saturated fatty acids and lack of such effects by n-3 PUFAs. However, it should be recognized that among the sources of dietary fat, animal fat with its high-saturated fatty acid content is by far the most important contributor, amounting to about 60%, to the Western diet. Importantly, dietary fat intake in the United States and Canada and other Western countries, where colon cancer rates are high, consists predominantly of a mixture of monounsaturated and polyunsaturated A recent in mice demonstrated that high dietary fat composition of the diet lesions in the colon of In of the of in colon cancer and because of potential properties of n-3 PUFAs, we have conducted a study to the effects of diets that contain rich in saturated fatty acids and to with the effects of fish oil during the different stages of colon carcinogenesis in male F344 preneoplastic lesions, were in fed the experimental diets for 23 and 38 which are putative preneoplastic lesions in the were observed at high in the colonic mucosa of patients with colon and of rats and mice treated with colon ACF and their are to be biomarkers of the effects of agents carcinogenesis in the colon. ACF were observed in the distal of rats. fed the diet a significantly greater of compared with those fed the corn oil or fish oil diet at time The incidence of aberrant foci was also higher in the diet group than in the or diet that administration of the diet significantly inhibits the and of preneoplastic lesions in the whereas the diet the of such Also, dietary significantly increased colon tumor incidence and when compared with the or Importantly, rats fed the diet incidence of colonic compared with incidences of and in rats fed the and Also, the of was significantly higher in fed the diet as compared to those fed the diet. the diet containing 20% fat in the of fish oil) induced tumors than diet containing the amount of total fat from This that both the type and the amount of fatty acids in the diet play a role in colon carcinogenesis. In evidence from preclinical studies is consistent with the epidemiologic The efficacy of dietary n-3 PUFAs including DHA and against colon carcinogenesis has also been in rodent models. et reported that administration of of DHA a for 4 and 12 significantly AOM-induced ACF in the colon. et also reported that administration of 1 of DHA a for 36 significantly AOM-induced colon tumor specifically in the and distal colon in male F344 rats. et compared dietary at LA at or LA at 5% against AOM-induced colon carcinogenesis in male rats. The indicate that the rats fed had a significantly lower colon tumor incidence and than those fed the LA diet. of tumors that the rats on diet had and more than those on the LA diet. Also, the content of in the colon tumors of LA diet group was higher than that in the colon tumors of the diet These suggest that its effect the modulation of in colon Several potential have been for colon cancer of types of dietary fat. Several studies indicate that diets high in saturated fatty acids and and n-6 PUFAs (corn oil or safflower oil) increase the of colonic acids, including acid and acid, whereas dietary fish oil high in n-3 PUFAs had no such enhancing epidemiologic studies demonstrated that populations who are on Western diet and at high risk for colon cancer high levels of acids have been to in a similar to induce cell proliferation and a in and act as in colon these suggest that acids that are by types of dietary fat may be important for in relation to colon tumor in by et dietary PUFAs may DNA and n-3 PUFAs may against colon carcinogenesis by DNA and/or enhancing DNA levels of AOM-induced DNA were in fish rats as compared to those fed corn oil rich in n-6 PUFAs. et and Chang et have also demonstrated that fish oil an increase in in the colon compared with corn rats. It is reasonable to that one of the by which n-3 PUFAs against colon carcinogenesis is in by the of DNA and by enhancing the of colonic Also, of fish oil or n-3 fatty acid increased and DHA levels in the of at the of n-6 fatty It has been that inhibition of colon carcinogenesis by DHA is the of a of a large of nuclear n-3 PUFAs effects in the colon the of nuclear of the nuclear are factors that cell and are studies to indicate that inducible nitric oxide synthase which is at the is in human colon and in chemically induced colon tumors of laboratory animal data also indicate that the of by is to carcinogenesis process and induces DNA lesions, thus in DNA and in the by family of also These data suggest a role for in tumor promotion and Studies conducted in our laboratory indicate that acid induces in intestinal with specific expression that one of the by which tumor including acids may an increase in expression of pathway that colon It is known that the fatty acid composition of is to diet. Studies conducted in our laboratory indicate that levels of dietary fish oil in rats increased the omega-3 fatty acids, DHA and in the colonic at the of omega-6 PUFAs such as linoleic acid and acid, the that the DHA and of fish oil the of by acid and linoleic acid in the Therefore, the types of dietary fat the fatty acid composition of colonic It is well that acid and of its including play an important role in the signaling pathway associated with cell proliferation and gene increase cell promote and of which are in tumor The by which n-3 PUFAs colon carcinogenesis are in of an important role in colon and who have in the of of rat intestinal epithelial have that of lead to the of high intake of saturated fat and omega-6 PUFAs acid from and 41 levels of have been observed in human colon tumors and chemically induced colon tumors in rodent and human colon levels of that are by Northern Recent have a between the potential of APC mutations and by that of the gene reduces the of tumors in mice for an by more than Additional evidence a role for from our which show a in colon tumors in rodents with Recent studies conducted in our laboratory have provided convincing evidence that an diet AOM-induced expression of and from acid in colon tumors of rats, whereas the diet inhibits the levels of In this study, administration of the diet of in the colon tumors, significantly higher levels than the corn oil diet or the diet 28 indicating higher This suggests that inhibition of the modulation of may be important for the of n-3 PUFAs to colon Also, colon tumors of fed the diet a lower than was observed in the colon tumors of rats fed the diet. The of these studies indicating that of in the tumors of fed the diet in to the diet inhibits and the tumor the that of lead to the of In colon tumors, the levels of may be to by proliferation and induction of and thus tumor A major that to be is which signaling are in of the These not only a between dietary fatty acids, and of colon but also molecular targets for colon cancer prevention by which n-3 PUFAs colon carcinogenesis. The potential and molecular events by n-3 PUFAs against colon carcinogenesis. The of molecular events by n-3 PUFAs include including and specific and factors including that cell and High dietary n-3 PUFAs by with the modification and of modulation of thus Recent studies from our laboratory have that high dietary n-6 PUFAs enhance of including that have been or in colon tumor whereas diet containing n-3 PUFAs to the of these a gene family of that play in signaling events and are in proliferation and include several with unique to the from the et reported that chemopreventive efficacy of dietary fish oil is associated with the alterations in colonic a that is by PUFAs may influence the of the which a of It is interesting that several have been to in The a of ras that is to the of in the of cell of are in the etiology of human colon It is also known that of from to is facilitated by a of closely including which is by It that inhibition of ras association of and neoplastic of Studies conducted in our laboratory have provided data to indicate that high dietary n-6 PUFAs increases expression in colonic tumors, whereas high dietary n-3 PUFAs appear to by with modification and of the modulation of thus Several have demonstrated against in both cell and laboratory animal in DNA have facilitated the of in promotion and of colon cancer. of is correlated with the development of certain of has also been to induce an effect that with and cell have recently that expression of was in colon tumors of rats than in colon Colon tumors from rats fed the diet containing high levels of n-6 PUFAs very low levels of whereas the tumors from fed the diet containing high amount of n-3 PUFAs did not of These correlate with colon tumor incidences by dietary n-3 and n-6 PUFAs. It appear that modulation of a significant role in n-3 colon tumor inhibition and Additional studies conducted in our laboratory have demonstrated that DHA inhibits of colon cancer in and induces we also the effects of DHA on the genetic of human colon cancer at the using DNA in gene expression due to DHA treatment was observed to be in the multiple signaling in the of cell and of DHA on cell and induction of were by an increase in the of several of family of and of such as and of several of these and factors the of the chemopreventive efficacy of DHA and other important n-3 PUFAs present in fish oil and thus colon cancer. Also, of these and factors provided several expressed biologic many of which suggest as molecular targets for by chemopreventive including nutritional is a major of and mortality in patients with cancer, including colorectal cancer. Several clinical studies have provided evidence for effects of fish oil administration in cancer during Omega-3 fatty acids have been to have effects on in cancer in patients with cancer is to and is associated with a time and of A fish nutritional has the potential to be a and of a fish oil preparation of and and a preparation in patients with 85 The of of the of which in the of of cancer patients and death from attributable to of of in cancer by and this may be one of the for inhibition of tumor Also, fish oil at a of during In on the basis of epidemiologic evidence from ecologic and it is reasonable to suggest that diets high in saturated fats increase the risk of colorectal cancer, whereas diets high in n-3 PUFAs not increase its risk. The studies both epidemiologic and evidence for the effects of diets rich in n-3 in the prevention of colorectal cancer. Also, recent clinical demonstrate effects of fish oil administration in cancer and during and studies have provided convincing evidence that colon tumor-promoting effect of dietary fat depends on its fatty acid that the composition of dietary fatty acids is more to colon cancer risk than is the total amount of fat. studies also demonstrate that a diet high in including saturated fats of animal origin as well as high dietary n-6 PUFAs had a higher potential to promote colon tumorigenesis than of a diet on amount of fat containing n-3 PUFAs. Although the by which diets high in saturated fats as those in Western and n-6 PUFAs promote colon carcinogenesis are not fully the studies conducted thus far indicate that increased levels of colonic acids, modulation of the influence on and the expression of by the types of dietary fat, especially n-6 PUFAs, may play a role in colon carcinogenesis. Further studies are to the role of n-3 PUFAs on the modulation of that are in colon and other types of cancer. The of prevention is to decrease the and mortality from colorectal cancer. and those of others suggest that nutritional prevention has the potential to be a major of colorectal cancer especially prevention in the are and in n-3 PUFAs be before they are for cancer Although there are no data to indicate and n-3 PUFAs should be for prevention of colorectal cancer, levels of dietary n-3 PUFAs should be consistent with the on epidemiologic studies of disease as by several These studies suggest that fish or as as g/day of fish the risk of Although a dietary for n-3 PUFAs not there is a that consumption of amount of fish in our on the epidemiologic studies may also reduce the risk of colorectal cancer. et has that the of n-6 PUFAs to n-3 PUFAs may be important for The varied risk for and several types of cancer among Mediterranean and Western European populations may at in be on the basis of n-6 to n-3 of and 10 in their on preclinical and epidemiologic studies on and et for a in the intake of linoleic acid and increase in the intake of n-3 PUFAs that a of 2 be for prevention of and that this is in Western countries for prevention of and and This may well be for the prevention of colorectal cancer in the Importantly, consumption of and is also for those in Western countries to reduce the risk of colorectal cancer. In the prevention of colorectal cancer in omega-3 fatty acids are in and of be It should be recognized that with nutritional supplements and/or diet modification may not be for prevention of colorectal cancer in patients such as those with polyposis and sporadic colon This to colon cancer is of importance as have not been fully in the high incidence or low of colorectal cancer. However, by diet modification as to the with chemopreventive agents that or the development of those which with and progress to and is an for prevention of colon cancer in these high-risk This is important when chemopreventive agents demonstrate significant efficacy but may effects at higher It is certain that colon cancer prevention be a significant of and in high-risk by molecular targets that or stop the process of carcinogenesis. there is a to clinical in patients with sporadic colon polyps using the n-3 diets in with a chemopreventive to the of events leading to The for preparation of the and studies on n-3 PUFAs in colon cancer prevention are supported by the Cancer Institute and

Current research on lipid metabolism in ruminants aims to improve the growth and health of the animals and the muscle characteristics associated with meat quality. This review, therefore, focuses on fatty acid (FA) metabolism from absorption to partitioning between tissues and metabolic pathways. In young calves, which were given high-fat milk diets, lipid absorption is delayed because the coagulation of milk caseins results in the retention of dietary fat as an insoluble clot in the abomasum. After weaning, the calves were fed forage- and cereal-based diets containing low levels of long-chain fatty acids (LCFA) but leading to high levels of volatile fatty acid (VFA) production by the rumen microflora. Such differences in dietary FA affect: i) the lipid transport system via the production of lipoproteins by the intestine and the liver, and (ii) the subsequent metabolism of lipids and FA by tissues. In preruminant calves, high-fat feed stimulates the secretion of triacylglycerols (TG)-rich lipoproteins (chylomicrons, very-low density lipoproteins (VLDL)). Diets rich in polyunsaturated FA (PUFA) stimulate the production of chylomicrons by the intestine (at peak lipid absorption) and of high density lipoproteins by the liver, leading to high blood concentrations of cholesterol. High levels of non-esterified FA (NEFA) uptake by the liver in high-yielding dairy cows in early lactation leads to TG infiltration of the hepatocytes (fatty liver). This is due to the low chronic capacity of the liver to synthesise and secrete VLDL particles. This abnormality in hepatic FA metabolism involves defects in apolipoprotein B synthesis and low availability of apolipoproteins and lipids for VLDL packaging. Fatty liver in calves is also caused by milk containing either soybean oil (rich in n-6 PUFA), or coconut oil (rich in C12:0 and C14:0). The ability of muscle tissue to use FA as an energy source depends on its mitochondrial content and, hence, on many physiological factors. The uptake and partitioning of LCFA between oxidation and storage in muscle is regulated by the activity of key intracellular enzymes and binding proteins. One such protein, carnitine palmitoyltransferase I (CPT I) controls the transport of LCFA into mitochondria. Metabolites derived from LCFA inhibit glucose oxidation, decrease the activity of CPT I and decrease the efficiency of ATP production by mitochondria. Most research on tissue lipid metabolism in ruminants is focused on: i) the partitioning of FA oxidation between intracellular peroxisomes and mitochondria in the liver and in muscles; (ii) the regulation of lipid metabolism by leptin, a recently discovered hormone secreted by mature adipocytes; and iii) the effects of activation of the nuclear receptors (PPARs and RXR) by LCFA or by phytol metabolites derived from chlorophyll.

Modulating fatty acid metabolism and composition of CHO cells by feeding high levels of fatty acids complexed using methyl-β-cyclodextrin.

The declining consumption of ruminant products has been partly associated with their high proportion (but not necessarily content) of saturated fatty acids. Recent studies have focused on the less prominent fact that they are also important sources of beneficial fatty acids, including n-3 fatty acids and conjugated linoleic acids. alpha-Linolenic acid (18 : 3n-3) is of particular interest because it also contributes to improved flavour of beef and lamb. Many recent studies showed large effects of special concentrates on levels of fatty acids in milk and meat. However, the 'rumen protection' treatments, needed to ensure a worthwhile level of fatty acid in products, are expensive. Herbage lipids are the cheapest and safest source of these fatty acids and so breeding to increase delivery of fatty acids from plants into ruminant products is an important long-term strategy. Plant lipids usually contain high levels of polyunsaturated fatty acids, particularly 18 : 2n-6 and 18 : 3n-3 which are the precursors of beneficial fatty acids. Whilst some plants are particularly rich in individual fatty acids (e.g. 18 : 3n-3 in linseed), there are also useful levels in grass and clover (Trifolium Spp.). Levels of fatty acids in forages in relation to species and varieties are considered, as well as management and conservation methods. Relationships between levels of fatty acids and existing traits and genetic markers are identified. The effects of forage treatments on the fatty acid content of ruminant products are reviewed. The higher levels of polyunsaturated fatty acids in milk from cows fed clover silages show that the level of fatty acids in herbage is not the only factor affecting levels of fatty acids in ruminant products. Further effort is needed to characterise susceptibility of unsaturated fatty acids to oxidative loss during field wilting and biohydrogenation losses in the rumen, and the relative importance of plant and microbial processes in these losses. The pathways of lipolysis and lipid oxidation are reviewed and other plant factors which offer potential to breed for reduced losses are considered.

Lean Australian red meat cuts are low in fat and have a ratio of cholesterol-raising saturated fatty acids (SFA) to cis-monounsaturated fatty acids (MUFA) to cis-polyunsaturated fatty acids (PUFA) of around 24:40:14. This is less cholesterol-raising than was earlier estimated, because cuts are now leaner and part of the SFA is stearic acid (that does not raise plasma cholesterol). and there are several other (cholesterol-lowering) PUFA as well as linoleic acid present. Low-fat, predominantly monounsaturated lean meat cuts have been shown to be acceptable in cholesterol-lowering diets. This does not mean that meat eaten with the fat on will not raise plasma cholesterol. Meat is low in sodium, high in potassium and has been shown in human dietary experiments not to raise the blood pressure. Meat is high in protein and contributes to weight reduction by increasing satiety and helping reduce intake in ad-lib weight-reducing diets. Overweight increases the risk of increased plasma cholesterol, increased blood pressure and diabetes. Meat is a good source of bioavailable iron. The hypothesis that people with high iron stores have increased risk of heart disease has not been confirmed in a number of epidemiological studies. Human studies suggest that dietary long-chain omega-3 PUFAs are protective against sudden cardiac death, consistent with lower risk of ventricular fibrillation. Most fat in the human diet is a mixture of triglycerides. The pattern of fatty acids attached to the glycerol has been known since 1956 to affect the plasma cholesterol concentration.1 The hardest evidence comes from strictly controlled metabolic ward experiments with metabolically normal human subjects. Saturated fatty acids (SFAs) raise the plasma cholesterol, polyunsaturated fatty acids (PUFAs) lower it, and monounsaturated fatty acids (MUFAs) have an intermediate, neutral effect.1,2 The cholesterol-raising effect of SFAs is about twice as potent as the lowering effect of PUFAs. This is expressed in Ancel Keys classic equation:2Δcholesterol = 2.74 ΔSFAs − 1.3 ΔPUFAs (where Δ = change; plasma cholesterol is in mg/100 mL and fatty acids are estimated as percentage of total daily calories). Hundreds of human experiments have since been conducted, many papers published, and we now have meta-analyses which strongly confirm the original findings.3,4 This is still the main message for public health education, but for health professionals, there are further modifications. Serum cholesterols nowadays are usually expressed in SI units, as mmol/L, so the numbers in the original Keys equation need to be divided by 38.6. Beyond serum total cholesterol, a knowledge of LDL-cholesterol (increases risk) and HDL-cholesterol (decreases risk) and triglycerides can better predict risk of coronary heart disease (CHD). Individual SFAs differ in their cholesterol-raising effect. PUFAs have different physiological effects if they belong to the omega-6 or omega-3 series. And different plant-derived oils, which contain predominantly MUFAs, do not all have the same effect on serum cholesterol, presumably because of the other lipids they contain (phytosterols, squalene).5 This paper outlines the effect of dietary components on risk of cardiovascular disease and considers the role of red meat in this context. Of the SFAs, only lauric (12:0), myristic (14:0) and palmitic (16:0) raise plasma cholesterol levels. Myristic is the most potent in this regard,6 and palmitic is the most abundant of all three in foods. SFAs with 10 or fewer carbon atoms (in medium chain triglycerides) do not appear to raise serum cholesterol.7 At the other end of the series, it has been repeatedly found that stearic acid (18:0) has little or no cholesterol-raising effect.8,9 It is rapidly converted to oleic acid in vivo. To estimate the effect of fatty acid pattern on serum cholesterol, it is better to refer to fatty acids with carbon chains of 12:0 + 14:0 + 16:0, rather than total SFA. Among the PUFAs, by far the most abundant in foods and oils is linoleic acid, cis 18:2, n-6. Hence, any effect on cholesterol attributed to PUFAs is due very largely to linoleic acid. The intake of PUFAs from food reported in the Australian 1995 National Nutrition Survey of 12.5 g/day10 was around 10 times greater than that reported for the linolenic acid (18:3), and about 100 times greater than that reported for eicosapentaenoic acid (EPA 20:5) + docosapentaenoic acid (DPA 22:5) + docosahexaenoic acid (DHA 22:6)—of about 130 mg/day.11 Linoleic acid is the only fatty acid known to lower plasma and LDL-cholesterol levels even when it is added to the diet, increasing fat and energy intakes.1,12 Other common PUFAs, linolenic (18:3, omega-3)7 and arachidonic13 (20:4, n-6), do lower plasma cholesterol, but this is of little practical importance because of their low levels in most foods. High-dosefish oils may raise plasma LDL-cholesterol a little. This is perhaps due to SFA in the fish oil, together with EPA and DHA, but they raise HDL-cholesterol too.7 Beneficial effects of fatty fish and fish oils on cardiovascular disease are not from plasma cholesterol lowering, but from effects that include reducing the risk of ventricular arrhythmias and the tendency to thrombosis. All that has been written above assumes that the fatty acids have double bonds in the usual, natural CIS configuration. But if the MUFA or PUFA is in the TRANS configuration, the effect on serum cholesterol is similar to that of SFA14 and, with high intakes, HDL-cholesterol may be lowered as well.15 Most human experiments have been conducted with trans 9, 18:1, called elaidic acid. Trans-unsaturated fatty acids occur naturally in small percentages in ruminant meat and milk fat. They are produced by microorganisms in the rumen. The main natural trans-fatty acid in red meat is trans 11, 18:1, called vaccenic acid. Trans-fatty acids are also produced during hydrogenation of vegetable and fish oils to make harder fats in food processing. Here the isomers are chiefly trans 9 and trans 10, 18:1. Around half of the trans-fatty acids in the British diet16 and Australian diet17 were estimated to come from animal foods, and half from margarines and other processed fats.16 With reduction of the industrially produced trans-fatty acids since then, the proportion from ruminant fat may be higher. Effects of different fatty acids on total-cholesterol levels are approximately mirrored by effects on LDL-cholesterol levels. As to HDL-cholesterol levels, SFAs 12:0, 14:0 and 16:0 raise it, and unsaturated fatty acids have little effect on it.18 Fasting plasma triglycerides are lowered by omega-3 PUFAs. Effects of fatty acids on different plasma LDL- and HDL-cholesterol are summarised in Table 1. There is now a vast body of literature on the role of fatty fish, fish oils and long-chain omega-3 PUFAs in the prevention and amelioration of heart disease, as well as in supporting the development of infants and having a positive impact on several chronic diseases and mental function. This summary concentrates on CHD and long-chain omega-3 PUFA provided in diet as fatty fish (and less on the more numerous human experiments with pharmacological doses of fish oil). Interest started with observations in Greenland Eskimos living traditional lifestyles, who had high intakes of animal fat but low incidence of CHD. Their animal fat was largely marine animals—fish, seal, etc. Dyerberg et al. in the 1970s found their plasma fatty acids contained unusually high amounts of eicosapentaenoic acid (EPA),19 and they suggested this reduced the tendency to thrombosis via an altered pattern of prostanoids.20 In the early 1980s, researchers reported that fatty fish, as well as fish oils (both rich in omega-3 PUFAs), produced a much greater reduction of plasma triglycerides and VLDL than oils or foods rich in n-6 linoleic acid.21 By the mid-1980s, there were two further major discoveries. Kromhout and colleagues (one of the Seven Country Study team) reported that in the Zutphen (Dutch) cohort, people who ate more fish (about 1/3 fatty) experienced significantly fewer CHD deaths.22 The mechanism was not via any of the known risk factors for CHD; possibly there was reduced platelet aggregation. They produced a recommendation for one or two fish dishes a week in dietary guidelines for the prevention of CHD.22 At about the same time, researchers in Australia were finding that rats fed dietary fat rich in PUFAs showed significantly fewer episodes of ventricular fibrillation when a coronary artery was occluded. The protective effect of tuna fish oil was stronger than sunflower seed oil, especially in the reperfusion phase.23 These animal experiments were confirmed by others in the United States, working with cultured neonatal rat cardiac myocytes, that can be seen to contract rhythmically under the microscope. It was then found that polyunsaturated fat in the medium counteracts the effects of pharmacological agents that usually initiate arrhythmias.24 Since then, at least 13 cohort studies have been completed, involving over 200 000 subjects. Most studies found protective effects of fish, and these were significant in countries with high rates of CHD and in studies of high scientific quality.25 Two meta-analyses (with a somewhat different selection of studies) both found significantly lower relative risk of CHD death in regular fish eaters,26,27 and He et al.27 showed a striking dose–response relationship, where eating fish two to four times per week reduced the mortality risk to 0.77. From the animal experiments it would be expected that the effect of fatty fish consumption would be on prevention of sudden deaths due to ventricular fibrillation. This was indeed found in two intervention studies: with fish in Wales (the DART study),28 and with fish oil capsules in the Italian GISSI study.29 Later trials in patients with implanted cardioverter/defibrillators have not provided such clear answers,30,31 but these are very complex cases to manage. In the largest randomised controlled trial of patients with implanted cardioverter/defibrillators (n = 402), the trend in favour of fish oil was impressive but not statistically significant, although technical difficulties with recordings and poor compliance in taking the large fish oil capsules were reported.30 Recently, five expert bodies have made recommendations regarding omega-3 PUFA intakes. In 2004, the US Food and Drug Administration concluded that supportive, but not conclusive, research shows that consumption of EPA and DHA omega-3 may reduce the risk of CHD. The Scientific Advisory Group of Food Standards Australia New Zealand likewise considered the evidence was probable that fatty fish containing omega-3 PUFAs reduces the risk of CHD. In 2003, the Joint WHO/FAO Expert Consultation32 concluded that the evidence was convincing that fish and fish oils (EPA and DHA) reduce the risk of cardiovascular disease. The (Australian) National Heart Foundation33 advises that, to lower the risk of CHD in the general population, adults should consume two to three serves of fish (preferably oily fish) per week, thus obtaining 500 mg/day of marine omega-3 PUFA. The National Health and Medical Research Council's Dietary Guidelines for Australian Adults (2003, pp. 117–122),10 as the third point in its 20 pieces of practical advice on fats, say ‘Try to include in your diet fish high in omega-3 polyunsaturated fats—for example, sardines, tuna, salmon and herring’. When considering any possible effects of long-chain omega-3 PUFAs, note that trials with fish oils use much higher intakes than are obtainable from ordinary diets. In trials with food relatively high in omega-3 PUFAs, the OPTILIP Study34,35 found reduced fasting plasma triglycerides but no change in haemostatic factors or insulin. The Adelaide and Perth study (which did not get an acronym)36 found no differences in blood pressure, insulin or lipids, although red cell PUFA increased 50%. All this advice is about EPA (20:5) and DHA (22:6), the predominant omega-3 PUFAs in fish oil and oily fish. The third long-chain omega-3 PUFA is docosapentaenoic (DPA, or 20:5). Its concentration is about one-sixth of that of EPA and DHA in fish, and little seems to be known about its biological activity. The averages of these three fatty acids in herring, mackerel, pilchards, salmon, sardines and tuna are: 20:5 = 8.25%, 22:5 = 1.43% and 22:6 = 6.55% total fatty acids.37 When eaten, cholesterol, the sterol in the cell membrane of land animals, tends to raise plasma cholesterol, but less than might be expected. About half of the plasma cholesterol is synthesised endogenously from acetate in the liver, and there is a feedback mechanism so that this is downregulated if more is absorbed. Effects of dietary cholesterol on plasma cholesterol are inconsistent,38 evidently affected by the fatty acid composition of the diet and varying between individuals.39 In shellfish, the sterols are not of the cholesterol form;40 chromatography shows that they are mostly phytosterols from seaweed. Earlier bans on oysters, for example, in cholesterol-lowering diets were based on a chemical method that did not differentiate other sterols from cholesterol. Phytosterols (β-sitosterol, campesterol, stigmasterol, brassicasterol) are the corresponding sterols of plant cell membranes. They have a very similar chemical structure to cholesterol, only differing in one or two extra carbons at the side-chain end of the molecule. They reduce absorption of cholesterol by competitive inhibition. This affects both dietary cholesterol and cholesterol excreted in the bile, which is normally partly re-absorbed. In purified form (and higher intake), they can lower plasma cholesterol by a larger percentage than dietary cholesterol raises it.41 Dietary fibre,42,43 even coffee,44 can affect plasma lipids, but the most important dietary factor, other than type of dietary fat, is excess energy, leading to overweight. Overweight people tend to have raised plasma triglycerides and higher total LDL-cholesterol and lower HDL-cholesterol.45 Weight reduction by diet and/or exercise will usually reduce their cholesterol and triglyceride levels. In 1981 Sullivan46 suggested that the lower incidence of CHD in premenopausal women, compared with men and postmenopausal women, could be due to higher iron stores in the latter two groups. A number of studies have since investigated this possibility. As red meat is a major source of bioavailable iron, this question is of potential concern for the safety of high intakes. The Institute of Medicine in its dietary reference intake (DRI) report on 14 nutrients,47 including iron, reviewed the literature on high iron status and CHD to determine the tolerable upper intake level. They found: Serum ferritin and CHD: three positive, five negative studies Transferrin saturation and CHD: all five studies negative Serum iron and CHD: all four studies negative Total iron binding capacity and CHD: all four studies negative Sempos explained why the US Food and Nutrition Board had concluded that there was not enough evidence to support the hypothesis.48 At least one of the positive studies was seriously flawed. Also, there is no consistent convincing evidence that having haemochromatosis, especially the heterozygous form, is associated with an increased risk of CHD. This was against the background that iron deficiency remains the most common nutritional deficiency in the USA.48 In the large West of Scotland pravastatin trial, genotypes for the haemochromatosis gene were assayed in 482 people who developed a CHD event and 1100 who did not.49 There were no significant differences. A recent trial of phlebotomy in 1277 US veterans with symptomatic peripheral arterial disease and 4.5-year follow up found no difference in outcome between phlebotomy and controls or with reduction of iron stores.50 Perhaps this topic can best be summed up by noting that the ANZ NRV report11 did not address the iron stores/CHD question. A recent paper by the Harvard epidemiologists Qi et al. suggests that dietary haem iron is a risk factor for CHD in women with type 2 diabetes.51 The three tables in the paper do not appear to show how much haem iron or meat (including pig meat) was recorded for the different quintiles. The authors themselves admit that residual confounding by saturated fat was unavoidable even after careful adjustment. The Australian Dietary Guidelines (ADG) Report10 presents the SFA and MUFA contents of lean red meat as quite low, especially in lean beef (total fat 1.8 g/100 g), and about equal, with smaller amounts of PUFA. Recent data on individual fatty acids in red meat52 expressed as percentages of total fatty acids suggest, for example that lean beef rump contains less cholesterol-raising SFAs and more PUFAs (Table 3). As per cent of total fatty acids, the values for: SFA (14:0 + 16:0) are 2.6 + 21.8 = 24.4% cis-MUFA (16:1 + 18:1) are 3.0 + 36.5 = 39.5% cis-PUFAs are 5.6 + 0.8 + 0.7 + 2.8 + 1.9 + 2.9 = 14.7% trans-fatty acids (18:1, 18:2 and 18:3) are 2.5 + 0.5 + 0.3 = 3.3% Most of the balance is stearic acid (13.2%) plus small amounts of 15:0, 17:0 and 14:1 fatty acids. The P/S ratio here is 0.60, whereas if the table in the Dietary Guidelines report is used, it would be only 0.22. Even if conjugated linoleic acid, 20:3, 20:5 and 22:6, are left out, the effective P/S for plasma cholesterol level is at least 10.3/24.4 = 0.42. The effect of red meat on plasma cholesterol in practice corresponds to what would be predicted from these recent Australian analyses of individual fatty acids in red meat cuts. Several controlled human studies find that lean red meat has a roughly neutral effect among foods on plasma cholesterol, suggesting it can be included in a cholesterol-lowering diet. A number of studies have shown the benefits of including lean red meat in prudent diets for cholesterol lowering. A group at St Thomas's Hospital London were able to reduce total- and LDL-cholesterol considerably in 15 free-living men with hyperlipidaemia on a diet, including increased P/S ratio and extra fruit and vegetables, that contained 180 g/day of lean red meat (8.5% fat). They concluded that providing care is taken to reduce total dietary fat, a moderate amount of meat and meat products may be included in a cholesterol-lowering diet.53 In Australia, Kestin et al. compared two fat-modified diets in 26 healthy men. One diet was vegetarian (LOV); the other contained 250 g/day lean meats (LOM). Total cholesterol fell 5% on diet LOM (10% on LOV). They concluded that a more widely accepted lean meat-containing prudent diet was almost as effective at lowering cholesterol levels as a plant-based prudent diet.54 Another Australian study involved 10 healthy subjects (men and women) given a very low-fat diet containing lean beef (500 g/day). Serum total cholesterol fell 20% and rose when beef dripping was added. The authors concluded that it was the beef fat, not lean beef itself, that was associated with elevations in cholesterol concentrations. The suggestion was that lean beef could be included in cholesterol-lowering diets (low saturated fat) provided that the meat was free of all visible fat.55 A further study in Texas, USA, gave 38 free-living men with hypercholesterolaemia a reduced-saturated-fat diet that included about 170 g either lean beef (8% fat) or chicken (7% fat) for five weeks. LDL-cholesterol fell 9% and 11% respectively, but the difference was not statistically significant. The authors concluded that lean beef and chicken were interchangeable in the NCEP Step 1 diet.56 In a long-term trial conducted in Chicago, Minneapolis and Johns Hopkins Lipid Clinic, 191 men with moderate hypercholesterolaemia were given 170 g/day of either lean red meat or lean white meat in their NCEP Step 1 diets. At the end of 36 weeks, LDL-cholesterol declined 1.7% and HDL-cholesterol increased 2.3% on the red meat; changes in the white meat group were not significantly different. (Lean red meat here, as is usual in the USA, was beef, veal or pork; lean white meat was poultry or fish.)57 Two other points are important about meat and plasma cholesterol. First, there is as much cholesterol in lean meat as in meat fat, chicken contains rather more cholesterol than beef, and kidney and liver contain four or five times more than muscle meat (see Table 2). These organs are richer in several good nutrients as well.37 Second, the fat of red meat has a more unfavourable fatty acid pattern than lean muscle meat. It contains more 14:0 and 16:0 SFA and less PUFA (see Table 3). By the method suggested above (omitting stearic acid), the P/S ratio in this lean meat is 0.42, while in the fat, it is 0.07. Of course, it contains about 20 times more total fatty acids than the lean muscle meat. This difference was first noted by Crawford,58 who compared the fatty acid patterns between very lean wild herbivores like and The to foods low in meat is a Australian analyses g in lean and British food tables similar for lean beef cuts the other lean red meat is rich in Australian for beef and mg/100 g for that about 9 The ratio is et blood of two of people with a moderate of One group ate 250 g/day of red meat for in of foods that the group was blood were significantly lower in the meat The authors suggest that the extra and in the meat may have added to the effect of less in reducing blood pressure. The against weight and the background papers the role of diet in the prevention and of and The report on the of a high body but does not a of which diets can be In the since the report was there has been research and much to find weight-reducing diets that are acceptable and The Total may much of its to the high protein of total energy and based this diet on their with diets reported in at least papers in the literature during the In one they report that over weeks, the diet in better changes in total- and in triglycerides and in blood compared with a diet, with no effects on or weight and in the men were not significantly different between the two possibly because of the of the et showed greater weight reduction with a protein intake of energy, compared with over a dietary Other have had similar with a dietary protein has been shown in human experiments to satiety and The for these changes have not been Low-fat, predominantly lean meat cuts have been shown to be acceptable in cholesterol-lowering diets. Meat is a good source of bioavailable iron, which does not appear to be a risk factor for heart disease. Meat is low in and high in and meat consumption does not appear to raise blood pressure. Overweight increases the risk of increased plasma cholesterol, increased blood pressure and diabetes. Meat is high in protein and contributes to weight reduction by increasing satiety and helping reduce energy intake in ad-lib weight-reducing diets.

Brewers’ spent grain (BSG) constitutes the primary by-product of the brewing industry. The valorization of BSG from a circular economy perspective is of high industrial interest. The objective of this study was the exploitation of BSG for the microbial production of branched-chain fatty acids (BCFAs) and polyunsaturated fatty acids (PUFAs), representing two different classes of high-value fatty acids (FAs). In the present study, this waste material underwent treatment with hot water in an autoclave and the resultant extract was utilized for the preparation of a novel liquid medium (BSG medium) to be employed for microbial fermentation. Screening and subsequent scaling-up experiments confirmed the suitability of the BSG medium to support the microbial production of various high-value FAs. In particular, Streptomyces jeddahensis and Conidiobolus heterosporus could be employed for BCFAs production, Pythium ultimum and Mortierella alpina could be used to provide cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and arachidonic acid (ARA), whereas Mucor circinelloides, when grown in a BSG medium, was able to accumulate γ-linolenic acid (GLA).

Suggested risk factors for postoperative thrombosis such as high fatty acid levels, hypercholesterolemia and diabetes are common in obese patients. In a retrospective study, the case records of 328 patients operated for obesity by gastric procedure from September 1977 until December 1993 were analyzed: 253 women and 75 men with a mean age of 38 years and a mean body mass index (BMI) of 44 kg/m2. The operation time, use of epidural anesthesia, and the occurrence of risk factors; fatty acid levels, hypercholesterolemia and diabetes were recorded. Symptomatic thromboses were verified by phlebography or phlethysmography and pulmonary embolism with ventilation/perfusion scintigraphy or autopsy. The mean operating time was 128 minutes, 77% had epidural anesthesia and the mean hospital stay was 12.3 days. The long hospital stay was due to the fact that most patients took part in different scientific studies perioperatively. The incidence of thromboembolism was 2.4%. Four patients had pulmonary embolism, in one of them this was fatal. Three patients had deep leg vein thrombosis and one patient had arm thrombosis secondary to a central venous catheter. None of these patients had high fatty acids, diabetes or high cholesterol. Of the patients, 298 were given dextran-70 (Macrodex, Pharmacia) as prophylaxis, seven were given heparin and 23 were given no prophylaxis. In the patient group without diagnosed thrombosis, 31% had high fatty acid levels, 2% had high cholesterol levels and 9% had diabetes. Obese patients seem to have a moderate risk of developing postoperative thrombosis when an effective prophylaxis is used. High free fatty acids, hypercholesterolemia and diabetes are not obvious extra risk factors in obese patients. Thromboprophylaxis should be given to all operated obesity patients regardless of age. The surgeons must be aware and investigate promptly any symptoms suggestive of thromboembolism.

Over the past 100 years, changes in the food supply in Western nations have resulted in alterations in dietary fatty acid consumption, leading to a dramatic increase in the ratio of omega-6 (omega6) to omega3 polyunsaturated fatty acids (PUFA) in circulation and in tissues. Increased omega6/omega3 ratios are hypothesized to increase inflammatory mediator production, leading to higher incidence of inflammatory diseases, and may impact inflammatory gene expression. To determine the effect of reducing the omega6/omega3 ratio on expression of inflammatory pathway genes in mononuclear cells, healthy humans were placed on a controlled diet for 1 week, then given fish oil and borage oil for an additional 4 weeks. Serum and neutrophil fatty acid composition and ex vivo leukotriene B(4) production from stimulated neutrophils were measured at the start and end of the supplementation period and after a 2-week washout. RNA was isolated from mononuclear cells and expression of PI3K, Akt, NFkappaB, and inflammatory cytokines was measured by real-time PCR. A marked increase was seen in serum and neutrophil levels of long-chain omega3 PUFA concomitant with a reduction in the omega6/omega3 PUFA ratio (40%). The ex vivo capacity of stimulated neutrophils to produce leukotriene B(4) was decreased by 31%. Expression of PI3Kalpha and PI3Kgamma and the quantity of PI3Kalpha protein in mononuclear cells was reduced after supplementation, as was the expression of several proinflammatory cytokines. These data reveal that PUFA may exert their clinical effects via their capacity to regulate the expression of signal transduction genes and genes for proinflammatory cytokines.

Studies in animals and geographic correlations across populations suggest that fatty acid intake may have a positive relationship with breast cancer risk, but analytic epidemiologic studies of fat intake have been less supportive. Adipose tissue analysis provides a more objective assessment of intakes of fatty acids that are not endogenously synthesized than do the questionnaire survey methods used in many epidemiologic studies. This case-control study of postmenopausal women was designed to examine the relationship between fatty acid composition of subcutaneous adipose tissue and risk of breast cancer and proliferative benign breast disease. In addition, we examined specific hypotheses that breast cancer risk is negatively associated with long-chain N-3 fatty acid intake, positively associated with trans fatty acid intake, and positively associated with increased intake of polyunsaturated fat together with low intake of antioxidants. Aspirates of subcutaneous fat from the buttocks were obtained from 380 women with newly diagnosed stage I or II breast cancer and 176 with proliferative benign breast disease. A total of 397 women who were evaluated for breast abnormalities at the same institutions but did not require breast biopsy or whose biopsy revealed nonproliferative benign breast disease served as the control group. We examined associations between saturated, monounsaturated, polyunsaturated, trans, or long-chain N-3 fatty acids and breast cancer, atypical hyperplasia, or proliferative benign breast disease without atypia. We observed no consistent patterns of association between breast cancer risk and any of the categories of fatty acids or the individual constituent fatty acids in the adipose tissue. Saturated fatty acids were inversely associated with risk of proliferative benign breast disease without atypia but not with atypical hyperplasia or breast cancer. This association was not observed, however, when total fat intake was taken into account. Women with high levels of polyunsaturated fatty acids in adipose tissue and low serum or dietary levels of antioxidants were not observed to be at higher risk of breast cancer. Using an objective measure of intake, we observed no major associations between polyunsaturated fatty acids, including long-chain N-3 fatty acids and trans fatty acids, and risk of breast cancer or proliferative benign breast disease. These data do not support the hypothesis that intake of specific fatty acids, particularly polyunsaturated and trans fatty acids, is an important risk factor for malignant or benign breast disease.

High linoleic acid levels in red blood cells predict a poor response to neoadjuvant chemotherapy in human epidermal growth factor receptor type 2-positive breast cancer patients