Impact Of Dietary Fat Research Articles

The impact of dietary fat and thyroid function on adipose conversion in male Sprague Dawley rats (1160.10)

The thyroid hormones (THs) play critical roles in differentiation, growth and metabolism and are critical for the normal function of nearly all tissues, with major roles in regulating energy balance, metabolism of glucose, and lipids and metabolic rate. The two functionally different types of fat in mammals are: brown adipose tissue (BAT), containing specialized thermogenic brown adipocytes, and white adipose tissue (WAT), containing white adipocytes specialized in triglyceride metabolism. Both tissues are strongly involved in energy balance. The objective of this study was to evaluate and compare physiological and histological effects of saturated and unsaturated fats in periadrenal BAT and thyroid gland of euthyroid and thyroid altered rats. Adult male Sprague Dawley rats (n=100) were exposed to a control or one of four test diets; 25% and 27% (saturated or unsaturated) for 8 weeks. A chemically reduced thyroid state was obtained through the addition of .05% propylthioracil (PTU) in drinking water. The body weights of the normal animals were significantly higher than in the altered thyroid groups. Histopathological evaluations confirmed damage to thyroid tissue in the altered thyroid groups and revealed an increase in BAT to WAT conversion in the thyroid gland and periadrenal BAT. Gene expression of FABP and LXR was generally higher in thyroid altered animals compared to the euthyroid group. In conclusion, chemically induced hypothyroidism negatively impacted fat metabolism, which contributed to increased BAT to WAT conversion and increased expression of FABP and LXR.

Impact of dietary fats on fatty acids profile of threatened Asian cafish (Clarias batrachus, Linnaeus, 1758)

Different fats in the diets were used to examine their impact on the fatty acid profile of asian catfish(Clarias batrachus) on feeding the diets for 12-weeks. There were seven treatments (FISOL, BETAL, SOYAL, LINOL, MIXOL, SATOL and NATFO containing Fish oil, Beef tallow, Soybean oil, Linseed oil, Mixed oil (i.e. containing in 1:1:1:1 ratio of Fish oil, Beef tallow, Soybean oil, Linseed oil), Vegetable oil and minced chicken meat as natural food, respectively, each with three replications, stocked with 30 grow-out having an initial average weight 55.83 + 3.14g in a circular plastic pools (capacity 300 L). The six feeds were formulated with basic ingredients (Soybean meal, 35%; soluble starch, 29%; Casein, 19.5%; carboxy - methyl - cellulose, 2%; papain, 0.5%; vitamin and mineral mix, 4.0%) with iso-energetic (19.55 kJ/g, F1-F6 ) diets and results were compared with natural food (F7) fed fishes. Each diet was hand fed two times daily during experimental period to triplicate homogenous groups of 30 fish. The muscle fillet polyunsaturated fatty acids (PUFA) content varied with different lipid levels suggesting that the dietary fat has impact on deposition of fatty acid in flesh. The muscle unsaturated fatty acids, including Docosa-hexaenoic acid (22:6n3, DHA) level, were comparatively higher in MIXOL diet followed by NATFO and LINOL diets, indicating selective deposition of fatty acids. It was concluded that addition of various fats in the diet has role in the composition of carcass fatty acid profile in Clarias batrachus and the MIXOL (Fish Oil : Tallow : Soybean Oil : Linseed Oil :: 1 : 1 :1 :1 w/w) could be safely used for better and/ or more deposition of healthy fatty acids (EPA and DHA) which are considered as human health beneficial fatty acids and also useful to economize the cost of the broodstock feed.

Abstract P163: Global and Regional Consumption of Specific Dietary Fats and Dietary Cholesterol in 1990 and 2005: Systematic Analysis of Country-Specific Nutrition Surveys Worldwide

Background. Assessing the impact of diet on chronic diseases worldwide has been limited by availability only of food disappearance data rather than reliable and systematically assessed consumption data on dietary habits globally. Objective. To review and access published and unpublished national diet surveys worldwide in a systematic and consistent way to produce comprehensive intake data of specific dietary fats and their uncertainties by country, region, age, and sex in 1990 and 2005. Methods. We developed methods to identify, assess, and obtain exposure data (mean, SD) from nationally representative diet surveys worldwide on saturated, n-6, n-3 and trans fats, and dietary cholesterol. To address missing data and estimate mean intake, we developed and applied a multi-level hierarchical Bayesian model that accounted for country- and region-level data, measurement comparability, study representativeness, and diet assessment method. Time-varying country-level covariates were used to inform the estimates, including FAO food availability data, population, GDP, latitude, metabolic risks, and other diet covariates. Uncertainty of the estimates accounted for uncertainty from sampling and statistical modeling. Results. We obtained relevant data (85% by direct author contact) from 76 nationally representative and 15 large regional surveys from 49 countries in 15 regions, covering 75% of the world’s population. Several countries and regions lacked representative data. Data were most frequently available for saturated fat and dietary cholesterol (Figure). Results for other fats will be presented at the meeting. Conclusions. These new methods developed to systematically assess, compile and estimate the exposure distribution of specific dietary fats and cholesterol in a uniform fashion globally allow, for the first time, characterization of consumption habits and trends by country, region, age and sex. Such global assessment is imperative for estimating the impact of dietary fats on chronic diseases worldwide.

A review of the evidence for the effects of total dietary fat, saturated, monounsaturated and n-6 polyunsaturated fatty acids on vascular function, endothelial progenitor cells and microparticles

Vascular dysfunction is recognised as an integrative marker of CVD. While dietary strategies aimed at reducing CVD risk include reductions in the intake of SFA, there are currently no clear guidelines on what should replace SFA. The purpose of this review was to assess the evidence for the effects of total dietary fat and individual fatty acids (SFA, MUFA and n-6 PUFA) on vascular function, cellular microparticles and endothelial progenitor cells. Medline was systematically searched from 1966 until November 2010. A total of fifty-nine peer-reviewed publications (covering fifty-six studies), which included five epidemiological, eighteen dietary intervention and thirty-three test meal studies, were identified. The findings from the epidemiological studies were inconclusive. The limited data available from dietary intervention studies suggested a beneficial effect of low-fat diets on vascular reactivity, which was strongest when the comparator diet was high in SFA, with a modest improvement in measures of vascular reactivity when high-fat, MUFA-rich diets were compared with SFA-rich diets. There was consistent evidence from the test meal studies that high-fat meals have a detrimental effect on postprandial vascular function. However, the evidence for the comparative effects of test meals rich in MUFA or n-6 PUFA with SFA on postprandial vascular function was limited and inconclusive. The lack of studies with comparable within-study dietary fatty acid targets, a variety of different study designs and different methods for determining vascular function all confound any clear conclusions on the impact of dietary fat and individual fatty acids on vascular function.

Nutrient-induced inflammation in the intestine

To review our current understanding of the relationship between absorption of nutrients and intestinal inflammatory response. There is increasing evidence linking gut local inflammatory events with the intake of nutrients. Our recent studies, using the conscious lymph fistula rat model, demonstrate that fat absorption activates the intestinal mucosal mast cells. This is accompanied by a dramatic increase in the lymphatic release of mast cell mediators including histamine, rat mucosal mast cell protease II (RMCPII), as well as the lipid mediator prostaglandin D2 (PGD2). Clinical studies suggest that increased consumption of animal fat may play a role in the pathogenesis of inflammatory bowel disease. This impact of dietary fat may not be restricted to the gut but may extend to the whole body. There is evidence linking a high-fat diet-induced metabolic syndrome, with a low-grade chronic inflammatory state. In this review, we hope to convince the readers that fat absorption can have far reaching physiological and pathophysiological consequences. Understanding the relationship between nutrient absorption and intestinal inflammation is important. We need a better understanding of the interaction between enterocytes and the intestinal immune cells in nutrient absorption and the gut inflammatory responses.

Cardiovascular Risk in African American Women Attending Historically Black Colleges and Universities: The Role of Dietary Patterns and Food Preferences

There is a lack of data on the dietary patterns and food preferences of African American women attending historically Black colleges and universities (HBCUs). African American women have higher death rates from cardiovascular disease than White women, and the initiating events of cardiovascular disease often begin in young adulthood. The purpose of this study was to identify the dietary patterns and food preferences of African American college women, which may act as risk factors for cardiovascular disease. A convenience sample of 100 African American women, ages 18 to 40 years, was administered two surveys assessing food preferences and dietary patterns. The majority of the participants (65%) preferred high-fat foods, and most of the participants (87%) consumed more than 30% of their daily caloric intake from fat. There is a definite need for dietary education regarding the impact of dietary fat on cardiovascular health among college students.

Effect of different levels of fish oil and canola oil on DMI, milk production and blood metabolites of high producing Iranian Holstein dairy cows in early lactation

Supplemental fat sources are utilized in rations for dairy cows as a common method to increase the energy density of the diet to support energy demands for milk synthesis in early lactation (Heravi Moussavi et al, 2007). Although dietary fat supplementation increases the energy density of the diet, data on the relationship between the addition of dietary fat and the performance of lactating dairy cows are inconsistent because the impact of dietary fat is influenced by source of fat, method of processing, amount of fat included in the diet and stage of lactation. Canola seed which contains 40% fat is an excellent source of dietary fat high in unsaturated fatty acids and protein for dairy animals. Canola oil contains 51% oleic, 25% linoleic, and 14% linolenic acids. Fish oil (FO) also contains relatively high concentrations of two polyunsaturated fatty acids of the n-3 family: (EPA, C20:5) and (DHA, C22:6). Combination of fish oil with different plant oils has been studied previously but there are few studies which have examined the inclusion of fish oil in combination with canola oil. The aim of the present study, therefore, was to study the effects of different levels of fish oil and canola oil in early lactating Holstein cows.

New oral fat tolerance tests feature tailoring of the polyunsaturated/saturated fatty acid ratio to elicit a specific postprandial response

The impact of dietary fat on postprandial metabolic biomarkers for obesity-related chronic diseases, such as type-2 diabetes and cardiovascular disease, has received significant recent attention. However, there is no standard method to evaluate the postprandial response to dietary fat alone. Our goals were to develop a novel oral fat tolerance test (OFTT) consisting solely of emulsified lipids tailored for specific fatty acid compositions and to evaluate the functionality of specific ratios of polyunsaturated/saturated fatty acid (P/S) loading on postprandial triacylglyceride (TAG) concentrations. Two OFTTs of emulsified lipids were prepared with specific P/S ratios of 0.2 and 2.0. Physical characteristics of the fat blends, including TAG composition, melting point, and emulsion droplet size were quantified. Healthy, older (age>45 y) men (n=8) underwent an 8 h postprandial study wherein they received the OFTT treatment (either the P/S ratio of 0.2 or 2.0), with a total lipid load of 1 g/kg subject body mass. All subjects received both treatments separated by at least 1 week. Both the P/S 0.2 and 2.0 OFTT significantly elevated (p<0.05) blood TAG and free fatty acid concentrations for 8 h without increasing blood glucose or serum insulin concentrations. The predominant fatty acids contained in the P/S 0.2 (palmitic acid, 16:0) and 2.0 (linoleic acid, 18:2(n-6)) OFTT blends were significantly elevated in the blood (p<0.05) during their respective postprandial periods. We concluded that blood TAGs are elevated in a specific pattern through the administration of novel OFTTs with specific P/S blends without eliciting an insulin or glucose response.

Medical Nutrition Therapy – The Relationship of Dietary Fat and Carbohydrate Metabolism in Patients with Type 2 Diabetes

The optimal composition of macronutrient intake for people with type 2 diabetes has been a subject of much debate. There are differing lines of thought as to the appropriate amount of carbohydrate, protein and fat that should be consumed to best regulate glucose control. This article will review literature on macronutrient intake in relation to glucose control in patients with type 2 diabetes, with a special emphasis on the impact of dietary fat. Monounsaturated Fat The American Dietetic Association recommends that 60‐70% of total calories be derived from monounsaturated fat (MUFA) and carbohydrate for persons with type 2 diabetes.1 However, the specific amount and type of carbohydrate and fat in the diet has been the subject of numerous studies. A comprehensive meta-analysis in people with diabetes concluded that, compared with high-carbohydrate diets, high-MUFA diets improve glycaemic profiles and have a favourable impact on lipoprotein metabolism.2 Whether this is due to a direct impact on insulin secretion or from a reduction in the carbohydrate load has also been debated. One study3 found that diets with a high content of MUFA-rich foods provide a degree of metabolic control that is similar to or perhaps better than that obtained with a high-carbohydrate diet. The author postulates that a healthy diet does not necessarily have to be a low-fat one because a variety of MUFA-rich foods can be incorporated into the diet to increase palatability and therefore lead to better compliance.

Dietary fat reduction to reduce prostate cancer risk: controlled enthusiasm, learning a lesson from breast or other cancers, and the big picture

Breast and prostate cancer share similar intrinsic and extrinsic risk factors. Based on laboratory, ecologic/international comparison, and case-control studies, the impact of dietary fat or other fat subtypes has been suggested as a potential route to reduce risk. Recent large-scale prospective studies have failed to find an association between fat and breast cancer risk. These studies may provide some insight for researchers examining the relation between fat and prostate cancer. Prospective studies to date have also failed to find a consistent association between prostate cancer and fat intake. Some fat subtypes (eg, saturated fat) or other lifestyle changes (eg, obesity, physical activity) may affect risk and progression of these cancers when examining the sum total of the research, but more precise and specific investigations in humans are needed to address these issues. Other concerns, such as the impact of excess energy or overall caloric consumption on carcinogenesis, still need to be addressed, as well as other methodologic limitations of past investigations. Large gaps exist in environmental (eg, diet, lifestyle) and heritable causes of these diseases. Regardless, until more extensive research is completed, lifestyle changes should be recommended based on reducing morbidity and mortality from cardiovascular disease—the number 1 cause of death in the United States. Additionally, cardiovascular disease remains the number 1 or 2 cause of death in patients diagnosed with breast or prostate cancer. Practical and simple dietary changes should be encouraged by health professionals because they could improve the overall longevity and quality of patients’ lives. Numerous ongoing prospective studies of diet and cancer should provide researchers and the public with much-needed answers in this area.

Impact of dietary fat and fiber intake on nutrient intake of adolescents.

To evaluate the impact of fat and fiber intake on energy and nutrient intake of 15-year-old adolescents. Twenty-four-hour dietary recalls were collected on a random sample of 15-year-olds. Subjects were then categorized into groups based on fat and fiber intake, with 319 students meeting criteria for 1 of 4 dietary intake quadrants: low fat, low fiber; low fat, high fiber; high fat, low fiber; and high fat, high fiber. Students with medium fat or fiber intakes were excluded from the study. Low-fat and high-fat intake were defined as <30% and >40% of total energy intake, respectively. Low- and high-fiber intake were defined as <15 g/day and >20 g/day, respectively. Low-fat and high-fiber intake had a minimal impact on energy intake and did not adversely affect nutrient intake. High-fiber intake was associated with greater likelihood of adequate intake of vitamins A, B6, B12, and C; niacin; thiamin; riboflavin; folacin; magnesium; iron; zinc; phosphorus; and calcium. High-fat intake was associated with greater likelihood of adequate vitamin B12 intake. Significant differences in fat and fiber intake distributions were found for ethnic background and gender, with more non-white than white students in the high-fat groups and more males than females in the high-fiber groups. A low-fat and high-fiber diet meeting current nutrition recommendations does not adversely affect energy or nutrient intake, increases nutrient density of the diet, and increases the likelihood of adequate intake for several key nutrients.

Impact of Dietary Fat on Th1/Th2 Cytokine Gene Expression in the Pancreas and Gut of Diabetes-prone BB Rats

The effect of dietary n-3 or n-6 polyunsaturated fatty acids on the development of autoimmune insulitis was analysed in diabetes-prone BB rats. Litter-matched groups of rats received a standard open formula NIH-07 (National Institutes of Health, NIH) diet enriched with 10% fish oil, 10% flaxseed oil or with 10% palm oil plus 2% cholesterol during the period of insulitis onset (50–70 days of age). Analysis of cytokine gene expression in pancreatic RNA revealed an increase of IFN-γ and a decrease of IL-10 mRNA with onset of insulitis. When compared to unsupplemented NIH, none of the three fat-enriched diets depressed the rise of IFN-γ gene expression or the influx of leukocytes into islets. However, all of the fat-enriched diets led to significantly higher IL-10 mRNA levels. Although a specific anti-inflammatory effect of fish oil was not seen in the pancreas, a clear shift of the Th1/Th2 cytokine mRNA ratio towards Th2 was seen in the gut-associated immune system. We conclude that diets high in fat support IL-10 without suppressing IFN-γ gene expression in islet inflammation. A special anti-inflammatory effect of fish oil was not seen in pancreatic lesions of BB rats, although there was strong modulation of the IFN-γ/IL-10 mRNA ratio in the gut associated immune system.

The impact of dietary fats, photoperiod, temperature and season on morphological variables, torpor patterns, and brown adipose tissue fatty acid composition of hamsters, Phodopus sungorus.

We investigated how dietary fats and oils of different fatty acid composition influence the seasonal change of body mass, fur colour, testes size and torpor in Djungarian hamsters, Phodopus sungorus, maintained from autumn to winter under different photoperiods and temperature regimes. Dietary fatty acids influenced the occurrence of spontaneous torpor (food and water ad libitum) in P. sungorus maintained at 18 degrees C under natural and artificial short photoperiods. Torpor was most pronounced in individuals on a diet containing 10% safflower oil (rich in polyunsaturated fatty acids), intermediate in individuals on a diet containing 10% olive oil (rich in monounsaturated fatty acids) and least pronounced in individuals on a diet containing 10% coconut fat (rich in saturated fatty acids). Torpor in P. sungorus on chow containing no added fat or oil was intermediate between those on coconut fat and olive oil. Dietary fatty acids had little effect on torpor in animals maintained at 23 degrees C. Body mass, fur colour and testes size were also little affected by dietary fatty acids. The fatty acid composition of brown fat from hamsters maintained at 18 degrees C and under natural photoperiod strongly reflected that of the dietary fatty acids. Our study suggests that the seasonal change of body mass, fur colour and testes size are not significantly affected by dietary fatty acids. However, dietary fats influence the occurrence of torpor in individuals maintained at low temperatures and that have been photoperiodically primed for the display of torpor.

The impact of dietary fat and fiber on intestinal carcinogenesis

The effect of dietary fiber on intestinal carcinogenesis in animals is controversial. Some find that the addition of wheat bran or cellulose inhibits intestinal cancer in rats, while others report no effect. Such mixed results often are due to differences in the design of experiments. One important aspect in this regard is the amount of fat in the diet. Some fiber supplements inhibit cancer formation when the fat content is normal but not when it is high. However, a recent epidemiological study in Scandinavia showed a lower cancer incidence in a rural population compared with an urban area, in spite of the fact that the dietary fat content was high in both regions. There was a modest difference in the amount of fiber, and this may not have accounted completely for the variation in cancer incidence. Other dietary factors might have added inhibitory response to help overcome the promotional effect of an excessive amount of fat. The interaction among dietary components must be considered when designing animal experiments to assess the effect of fiber on cancer development.