Dietary Sterols Research Articles

Phylogeny and evolution of the cholesterol transporter NPC1 in insects

Sterols are essential nutrients for eukaryotes. Insects are obligate sterol auxotrophs and must acquire this key nutrient from their diets. The digestive tract is the organ for absorbing nutrients as well as sterols from food. In mice, the Niemann-Pick type C1 Like 1 (NPC1L1) gene is highly expressed in the intestine and is critical for cholesterol absorption. In contrast, the molecular mechanisms for the absorption of dietary sterols in insects have not been well studied. We annotated NPC1 genes in 39 insects from 10 orders using available genomic and transcriptomic information and inferred phylogenetic relationships. Insect NPC1 genes were grouped into two sister-clades, NPC1a and NPC1b, suggesting a likely duplication in the ancestor of insects. The former exhibited weaker gut-biased expression or a complete lack of tissue-biased expression, depending on the species, while the latter was highly enriched in the gut of three lepidopteran species. This result is similar to previous findings in Drosophila melanogaster. In insects, NPC1a accumulated non-synonymous substitutions at a lower rate than NPC1b. This pattern was consistent across orders, indicating that NPC1a evolved under stronger molecular constraint than NPC1b.

Tissue sterol composition in Atlantic salmon (Salmo salar L.) depends on the dietary cholesterol content and on the dietary phytosterol:cholesterol ratio, but not on the dietary phytosterol content.

The aim of the study was to investigate how the dietary sterol composition, including cholesterol, phytosterol:cholesterol ratio and phytosterols, affect the absorption, biliary excretion, retention, tissue storage and distribution of cholesterol and individual phytosterols in Atlantic salmon (Salmo salar L.). A feeding trial was conducted at two different temperatures (6 and 12°C), using nine different diets with varying contents of phytosterols, cholesterol and phytosterol:cholesterol ratio. Cholesterol retention values were clearly dependent on dietary cholesterol, and showed that fish fed cholesterol levels <1000 mg/kg feed produced considerable quantities of cholesterol de novo. Despite this production, cholesterol content increased with increasing dietary cholesterol in liver, plasma, bile, muscle, adipose tissue and whole fish at 12°C, and in plasma, bile and whole fish at 6°C. The tissue sterol composition generally depended on the dietary cholesterol content and on the dietary phytosterol:cholesterol ratio, but not on the dietary phytosterol content in itself. Campesterol and brassicasterol appeared to be the phytosterols with the highest intestinal absorption in Atlantic salmon. There was a high biliary excretion of campesterol, but not of brassicasterol, which accumulated in tissues and particularly in adipose tissue, with 2-fold-higher retention at 12°C compared with 6°C. Campesterol had the second highest retention of the phytosterols in the fish, but with no difference between the two temperatures. Other phytosterols had very low retention. Although brassicasterol retention decreased with increasing dietary phytosterols, campesterol retention decreased with increasing dietary cholesterol, indicating differences in the uptake mechanisms for these two sterols.

Cholesterol internalization and metabolism in insect prothoracic gland, a steroidogenic organ, via lipoproteins

Dietary sterols including cholesterol and phytosterols are essential substrates for insect steroid hormone (ecdysteroid) synthesis in the prothoracic glands (PGs). In the silkworm Bombyx mori, one of the model species of insects, the steroidogenesis has been well demonstrated that cholesterol biotransformation into ecdysone in the PG cells. Because insects lack the ability to synthesize cellular sterol de novo, lipoprotein, lipophorin (Lp), has been thought to be the major cholesterol supply source; however, details of cholesterol behavior from Lp to the PG cells has not been analyzed till date. In this report, we developed Lp incorporation method using labeled cholesterols such as 22-NBD-cholesterol and cholesterol-25,26,26,26,27,27,27-d7 (cholesterol-d7), and analyzed the internalization and metabolism of cholesterol in PGs in vitro using the silkworm Bombyx mori. The internalization of cholesterol was visualized using 22-NBD-cholesterol. PGs showed an enriched cellular 22-NBD-cholesterol signal, which dissociated from the Lp localizing at the close area of cell membrane. The distribution pattern observed in the PGs was different from other tissues such as the brain, fat body, and Malpighian tubules, suggesting that the internalization of cholesterol in the PGs was distinct from other tissues. The metabolism of cholesterol was traced using LC-MS/MS methods to detect cholesterol-d7, 7-dehydrocholesterol-d7 (an expected intermediate metabolite), and the final product ecdysone-d6. 7-Dehydrocholesterol-d7 and ecdysone-d6 were detected in the PG culture incubated with labeled Lp, showing that the cholesterol of Lp was utilized for ecdysone synthesis in the PGs. Our results reveal the distinct behavior of cholesterol in the PGs, with the first direct evidence of biochemical fate of lipoprotein cholesterol in insect steroidogenic organ. This will aid in the understanding of the involvement of lipoprotein cholesterol in steroid hormone synthesis in insects.

Oral Fat Tolerance Test for Sitosterolemia and Familial Hypercholesterolemia: A Study Protocol.

Aim: Sitosterolemia is an extremely rare, autosomal recessive disease characterized by high plasma cholesterols and plant sterols because of increased absorption of dietary cholesterols and sterols from the intestine, and decreased excretion from biliary tract. Previous study indicated that sitosterolemic patients might be vulnerable to post-prandial hyperlipidemia, including high remnant-like lipoprotein particles (RLP) level. Here we evaluate whether a loading dietary fat increases a post-prandial RLP cholesterol level in sitosterolemic patients compared to heterozygous familial hypercholesterolemic patients (FH).Methods: We recruit total of 20 patients: 5 patients with homozygous sitosterolemia, 5 patients with heterozygous sitosterolemia, and 10 patients with heterozygous FH as controls from May 2015 to March 2018 at Kanazawa University Hospital, Japan. All patients receive Oral Fat Tolerance Test (OFTT) cream (50 g/body surface area square meter, orally only once, and the cream includes 34% of fat, 74 mg of cholesterol, and rich in palmitic and oleic acids. The primary endpoint is the change of a RLP cholesterol level after OFTT cream loading between sitosterolemia and FH. We measure them at baseline, and 2, 4, and 6 hours after the oral fat loading.Results: This is the first study to evaluate whether sitosterolemia patients have a higher post-prandial RLP cholesterol level compared to heterozygous FH patients.Conclusion: The result may become an additional evidence to restrict dietary cholesterols for sitosterolemia. This study is registered at University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN ID: UMIN000020330).

Thematic Review Series: Lipid Transfer Proteins ABCG5 and ABCG8: more than a defense against xenosterols

The elucidation of the molecular basis of the rare disease, sitosterolemia, has revolutionized our mechanistic understanding of how dietary sterols are excreted and how cholesterol is eliminated from the body. Two proteins, ABCG5 and ABCG8, encoded by the sitosterolemia locus, work as obligate dimers to pump sterols out of hepatocytes and enterocytes. ABCG5/ABCG8 are key in regulating whole-body sterol trafficking, by eliminating sterols via the biliary tree as well as the intestinal tract. Importantly, these transporters keep xenosterols from accumulating in the body. The sitosterolemia locus has been genetically associated with lipid levels and downstream atherosclerotic disease, as well as formation of gallstones and the risk of gallbladder cancer. While polymorphic variants raise or lower the risks of these phenotypes, loss of function of this locus leads to more dramatic phenotypes, such as premature atherosclerosis, platelet dysfunction, and thrombocytopenia, and, perhaps, increased endocrine disruption and liver dysfunction. Whether small amounts of xenosterol exposure over a lifetime cause pathology in normal humans with polymorphic variants at the sitosterolemia locus remains largely unexplored. The purpose of this review will be to summarize the current state of knowledge, but also highlight key conceptual and mechanistic issues that remain to be explored.

Phytosterols are not involved in the development of fatty liver in plant oil fed Atlantic salmon (Salmo salar) at high or low water temperature

The increasing use of plant-based ingredients in aquafeeds for Atlantic salmon has led to increasing feed concentrations of plant sterols (phytosterols) combined with decreasing concentrations of cholesterol. Questions have been raised regarding how this may affect performance, health and lipid metabolism in a carnivorous fish species adapted to a high cholesterol diet in nature, and whether phytosterols could be involved in the liver lipid accumulation commonly observed in salmon fed diets with high content of vegetable oils.A feeding trial with 9 diet groups with varying additions of phytosterols and cholesterol was conducted at two temperatures (6 and 12°C). Fish grew from an initial weight of ~250g to a final weight of ~900g. Overall, the addition of phytosterols and/or cholesterol within the range tested (1353–3147mgkg−1 phytosterols, 867–3153mgkg−1 cholesterol and phytosterol:cholesterol ratios of 0.7–3.2) exhibited few effects on fish performance, lipid metabolism and health. The main hypothesis regarding phytosterols or phytosterol:cholesterol ratio affecting liver lipid accumulation appears to be false. However, dietary cholesterol did increase muscle pigmentation at both temperatures, while fillet dry matter and hepatosomatic index were also increased by dietary cholesterol at 12°C. Dietary cholesterol also had some minor effects on the fatty acid composition of liver polar lipids, probably mediated by LXR. In general, more effects were seen from variations in dietary cholesterol compared to phytosterols.The current trial is the first to feed salmon graded levels of phytosterols, cholesterol and their ratio without changing the dietary fatty acid composition, and thereby isolating the effects of dietary sterols.

Studies on secondary metabolite profiling, anti-inflammatory potential, in vitro photoprotective and skin-aging related enzyme inhibitory activities of Malaxis acuminata, a threatened orchid of nutraceutical importance

Malaxis acuminata D. Don., a small, terrestrial orchid, is endemic to tropical Himalayas at an altitude of 1200–2000m asl. The dried pseudobulbs are important ingredients of century old ayurvedic drug ‘Ashtavarga’ and a polyherbal immune-booster nutraceutical ‘Chyavanprash’, known to restore vigour, vitality and youthfulness. Considering tremendous medicinal importance of this threatened orchid species, a detailed study was undertaken for the first time to address its antioxidant potential, secondary metabolite contents and biological activities against skin-aging related enzymes (anti-collagenase, anti-elastase, anti-tyrosinase and xanthine oxidase) and anti-inflammatory activity (5-lipoxygenase and hyaluronidase) in different plant parts of wild and in vitro-derived plants of M. acuminata. Methanolic leaf and stem extracts were further evaluated for in vitro photoprotective activity against UV-B and UV-A radiations. Furthermore, secondary metabolite profiling of various plant parts was carried out by Gas Chromatography Mass Spectrometry (GC–MS). A significantly higher antioxidant potential (DPPH, metal chelating and ABTS•+) with a comparative higher yield of secondary metabolites was observed in in vitro-derived plantlets as compared to the wild plants. Among various solvent systems used, methanolic leaf and stem extracts showed promising inhibitory activity against major skin aging-related enzymes and anti-inflammatory potential. Methanolic leaf and stem extracts of both wild and in vitro-derived plants showed promising photoprotective activity against UV-B and UV-A radiations in vitro with comparatively higher sun protection factor (SPF). Furthermore, GC–MS analysis of methanolic extracts of leaves and stems of wild as well as in vitro-derived plantlets revealed presence of many bioactive metabolites such as, dietary fatty acids, α-hydroxy acids, phenolic acids, sterols, amino acids, sugars and glycosides which substantially explain the use of M. acuminata as one of the potential rejuvenator and anti-aging ingredient in many Ayurvedic formulations.

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized, Controlled Study.

A randomized, double‐blinded, placebo‐controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4‐wk daily exposure to plant sterols‐enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m2) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (β‐sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope‐labeled gas chromatography‐mass spectrometry. L‐arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 μmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 μmol/L) were significantly elevated after 4‐wk plant sterols supplementation Placebo and 3‐h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L‐arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, β‐Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4‐wk treatments compared to the placebo and 3‐h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo.

English

Malnutrition is the major problem in many countries of the world including Pakistan. Due to inadequate macro and micro nutrients, prevalence of diseases is increasing day by day. Haleem is a common diet that can be used by people of all age group. It is prepared by different methods and consists of Lens culinaris L., Hordeum vulgare L., Phaseolus vulgaris L., Vigna mungo L., Vigna radiate L., Cicer arietinum L., Oryza sativa L., Triticum aestivum L., Gallus gallus domesticus, Brassica napus L., Zingiber officinale Rosec., Curcuma longa L., Allium sativum L., Allium cepa L., Capsicum annuum L., Cinnamomum zeylanicum L., Cuminum cyminum L., Myristica fragrans Houtt, Piper longum L., Mentha piperita L., Amomum subulatum Roxb., Coriandrum sativum L., Mangifera indica L., Citrus lemon L. and rock salt. These materials either from plant, animal and mineral origin contain variety of substances such as dietary fibers, energy, proteins, carbohydrates, lignins, tannins, flavonoids, phytosterols, squalene, tocopherols, saponins, pre-biotics, plant acids, sterol, crude fibre, fats, vitamin and minerals. Key words: Neurological disorder, nutrition, micronutrients, macronutrients, bioactive compounds.

Structural Role of ABCG5/ABCG8 in Sterol Transport

ATP binding cassette (ABC) transporters play critical roles in maintaining sterol homeostasis in eukaryotic organisms, including yeast, plants and mammals. In humans, the heterodimeric ABCG5/ABCG8 (G5G8) mediates the excretion of cholesterol and dietary plant sterols into bile and into the gut lumen. Mutations inactivating either ABCG5 or ABCG8 cause sitosterolemia, a rare autosomal recessive genetic disorder characterized by plant sterol accumulation, hypercholesterolemia, and premature coronary atherosclerosis. ABCG5 and ABCG8 are half ABC transporters;each subunit consists of an N-terminal nucleotide-binding domain (NBD) and a C-terminal transmembrane domain (TMD). The NBDs dimerize to form two catalytically asymmetric nucleotide-binding sites (NBS), one that is catalytically active (NBS2) and the other inactive (NBS1). To understand the structural basis for G5G8-mediated sterol transport we developed a large-scale purification of human G5G8 by exploiting Pichia patoris yeast. We crystallized the transporter in lipid bilayers, solved its structure in a nucleotide-free state at 3.9 Å resolution, and generated the first atomic model of an ABC sterol transporter. G5G8 presents a new structural configuration for the TMD of ABC transporters, which is present in a large and functionally diverse ABC2 superfamily. We discover that the TMD and the NBS are coupled through networks of interactions that differ between NBS1 and NBS2, reflecting the catalytic asymmetry of the transporter. A series of conserved polar residues in the TMD form polar networks that we proposed play a role in transmitting signals from the ATPase catalysis in the NBS to sterol transport on the TMD. Molecular dynamic simulation and long-range coevolution analysis revealed an inward-upward TMD movement that predicts a significant conformational change between the TMD subunits. Thus, the G5G8 structure provides a molecular framework that allows us to propose a mechanistic model for ABC transporter-mediated sterol transport and to analyze the disruptive effects of mutations causing sitosterolemia. The structure will serve as a structural template for homology modelling to a wide range of transport system that is regulated by ABCG transporters and by ABC2 superfamily.

Interindividual variability in the cholesterol-lowering effect of supplementation with plant sterols or stanols.

Low-density lipoprotein cholesterol (LDL-C) plays a causal role in atherosclerosis. One way to reduce LDL-C levels is to inhibit cholesterol absorption. Plant sterols and stanols compete with cholesterol for absorption in the intestine and induce an average decrease in LDL-C by 5% to 15% in a dose-dependent manner, but not in all individuals. This review focuses on the interindividual variability in response to dietary supplementation with plant sterols and stanols. Dietary plant sterols and stanols have no significant effects on LDL-C in substantial numbers of individuals. Higher responses, in absolute value and percentage of LDL-C, are observed in individuals with higher cholesterol absorption and a lower rate of cholesterol synthesis. Some data provide evidence of the influence of genetics on the response to plant sterols and stanols. Further studies in large populations are required to extend these conclusions about genetic influences.

Effect of dietary cholesterol and plant sterol consumption on plasma lipid responsiveness and cholesterol trafficking in healthy individuals.

Dietary cholesterol and plant sterols differentially modulate cholesterol kinetics and circulating cholesterol. Understanding how healthy individuals with their inherent variabilities in cholesterol trafficking respond to such dietary sterols will aid in improving strategies for effective cholesterol lowering and alleviation of CVD risk. The objectives of this study were to assess plasma lipid responsiveness to dietary cholesterol v. plant sterol consumption, and to determine the response in rates of cholesterol absorption and synthesis to each sterol using stable isotope approaches in healthy individuals. A randomised, double-blinded, crossover, placebo-controlled clinical trial (n 49) with three treatment phases of 4-week duration were conducted in a Manitoba Hutterite population. During each phase, participants consumed one of the three treatments as a milkshake containing 600 mg/d dietary cholesterol, 2 g/d plant sterols or a control after breakfast meal. Plasma lipid profile was determined and cholesterol absorption and synthesis were measured by oral administration of [3, 4-13C] cholesterol and 2H-labelled water, respectively. Dietary cholesterol consumption increased total (0·16 (sem 0·06) mmol/l, P=0·0179) and HDL-cholesterol (0·08 (sem 0·03) mmol/l, P=0·0216) concentrations with no changes in cholesterol absorption or synthesis. Plant sterol consumption failed to reduce LDL-cholesterol concentrations despite showing a reduction (6 %, P=0·0004) in cholesterol absorption. An over-compensatory reciprocal increase in cholesterol synthesis (36 %, P=0·0026) corresponding to a small reduction in absorption was observed with plant sterol consumption, possibly resulting in reduced LDL-cholesterol lowering efficacy of plant sterols. These data suggest that inter-individual variability in cholesterol trafficking mechanisms may profoundly impact plasma lipid responses to dietary sterols in healthy individuals.

Anti-obese and Anti-hyperglycemic Effects of Dietary Triterpene Alcohols and Sterols from Rice Bran Oil

Anti-obese and Anti-hyperglycemic Effects of Dietary Triterpene Alcohols and Sterols from Rice Bran Oil

The effect of longer-term plant sterol and stanol consumption on apolipoprotein CII and apolipoprotein CIII concentrations in humans

Background: Elevated fasting and postprandial serum levels of triacylglycerol (TAG) are a risk factor for cardiovascular disease (CVD). The dietary components plant sterols and stanols can be used as strategy against elevated TAG levels. In a recent study it was found that longer-term plant stanol consumption resulted in a higher postprandial TAG response compared to sterol consumption after a second meal. The explanation for this observed difference remained unclear. Possibly the clearance of TAG from the blood might be affected differently. Specialized particles are responsible for the transportation of TAG in the blood, called the lipoproteins. These particles contain apolipoproteins CII (apoCII) and CIII (apoCIII) which have an activating and inhibiting effect on the enzyme lipoprotein lipase (LPL) responsible for the clearance of TAG from the blood. Objective: The objective was to examine if postprandial apoCII and apoCIII responses could explain observed differences in postprandial TAG response after longer-term sterol and stanol consumption. Methods: Healthy subjects (n=42) participated in a randomized control trial consisting of three intervention periods during which the participants consumed either control margarine, or margarine enriched with plant sterols or plant stanols. Blood was sampled under fasting conditions and after the consumption of breakfast and lunch. ApoCII and apoCIII concentrations in serum were measured by an immunoturbimetric immunoassay. Results: Both iAUC and iAUCmin of postprandial apoCII concentrations were similar between all three conditions ( p=0.965 and p=0.563 respectively). Postprandial iAUC and iAUCmin of apoCIII concentrations also showed no difference between conditions (p=0.342 and p=0.955 respectively). In the control group, the iAUC of postprandial apoCIII concentrations was higher after the second meal compared to the first meal. (p=0.037).Conclusion: Postprandial apoCII and apoCIII responses were not affected by longer-term plant sterol and stanol consumption, therefore changes in concentrations of these two apolipoproteins can be ruled out as explanation for the observed differences in TAG response

Plant sterol-enriched soy milk consumption modulates 5-lipoxygenase, 12-lipoxygenase, and myeloperoxidase activities in healthy adults – a randomized-controlled trial

A randomized, double blind, placebo-controlled and crossover study was conducted to simultaneously measure the effects, after 3-h and 4-week daily exposure to plant sterols-enriched food product, on inflammation, oxidative status, 5-lipoxygenase, 12-lipoxygenase, and myeloperoxidase activities in healthy adults. Eighteen healthy participants (67% female, 35.3 (mean) ± 9.5 (SD) years, mean body mass index 22.8 kg m−2) received two soy milk (20g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmitates (β-sitosterol, 55%; campesterol, 29%; stigmasterol, 23%). F2-isoprostanes, leukotriene B4, sitosterol, campesterol, and stigmasterol concentrations were measured in the blood plasma and urine, using stable isotope-labeled gas chromatography–mass spectrometry. High-sensitivity c-reactive protein, tumor necrosis factor-α, and lipoxin A4 concentrations in blood serum were measured using commercially available enzyme immunoassays. Myeloperoxidase activity, serum lipid hydroperoxides, plasma and urinary F2-isoprostanes, plasma and urinary leukotriene B4, and plasma high-sensitivity c-reactive protein concentrations were significantly reduced, while circulating lipoxin A4 concentrations were significantly elevated after 4-week plant sterols treatment. Plant sterols treatment decreased plasma leukotriene B4 and increased plasma lipoxin A4 concentrations acutely. Total plant sterols, β-sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4-week treatments compared with the pre-treatment concentrations. Our results suggest that dietary plant sterols, in the combination used, can alleviate lipid peroxidation and inflammatory events in vivo. These effects are possibly exerted via the modulation of myeloperoxidase, 5-lipoxygenase, and 12-lipoxygenase activities.

Abstract 628: Efficient Excretion of Xenosterols in the Absence of Abcg5/Abcg8

Hypothesis: Xenosterol excretion by the mammalian body is wholly dependent on Abcg5/Abcg8 function. Methods: To test our hypothesis, we loaded Abcg8-/- mice with dietary plant sterols until they manifested biochemical (elevated plant sterols) and pathological changes (poor body weight, macrothrombocytopenia). All dietary xenosterols were eliminated from the diet and kinetics of xenosterol loss monitored over the ensuing 16 days, monitoring plasma, bile, and stool losses, as well as whole body sterol determinations. Results: After loading Abcg8-/- mice with plant sterols, plasma sitosterol levels in both male and female mice averaged 80mg/dL. Surprisingly, there was rapid loss of xenosterols from blood as well as tissues (liver, whole body), with losses of xenosterols detected in bile and feces. By day 16, stool xenosterols were almost undetectable and reflected the dramatic loss of whole body xenosterols. Conclusions: Our data refute our hypothesis. Although loss of sterolin function leads to severe xenosterolemia in both humans and mice, at least in mice, there appears to be a pathway(s) for elimination via the biliary/intestinal route. Characterization of the transporters involved may shed further light on sterol trafficking.

Growth performance, tissue composition, and gene expression responses in Atlantic salmon (Salmo salar) fed varying levels of different lipid sources

We investigated the influence of dietary fatty acid (FA) composition on growth performance, muscle tissue FA composition, and lipid-related hepatic gene expression in Atlantic salmon. Currently the commercial feed industry primarily uses terrestrial-based fats and oils as the main lipid component in the diet, with minimal provision of fish oil (FO). Therefore, we compared the growth and tissue FA response of salmon smolts (mean initial weight 256gfish−1) after 16weeks on three different terrestrial-based diets, with inclusion at three increasing levels of substitution with FO. The lipid sources used in this study were: FO, camelina oil (CO), canola oil (CA), and camelina oil with poultry fat (CO+PF). The terrestrial-based lipid sources had different FA signatures, on account of varied proportions of the C18 FA: 18:2n−6, 18:3n−3, or 18:1n−9. Inclusion of terrestrial FA and removal of marine FA (20:5n−3, 22:6n−3) were reflected in the FA composition of the muscle, and affected growth performance (based on lipid source and inclusion level) and hepatic gene expression of several lipid metabolism-relevant genes. Multiple regression analysis revealed that dietary lipid source affected growth performance, even when inclusion level (as a replacement of FO) was not a factor; suggesting that either inclusion or removal of certain FA in particular lipid sources, even at minimal levels, influenced growth performance. A breakpoint analysis of final weight indicated that dietary levels of <1% each of 20:5n−3 and 22:6n−3 resulted in lower final weight. A multidimensional scaling plot showed that the muscle tissue FA composition of salmon fed diets with CO were distinguishable from salmon fed CA and PF, mainly on account of 18:3n−3, while salmon fed FO were distinct from the terrestrial-based treatments. Salmon fed CO diets maintained 22:6n−3 levels in muscle tissue, and increased in n−3 and n−6 intermediary biosynthesis products in the muscle suggesting endogenous production of 22:6n−3 via dietary 18:3n−3. In addition, significant correlations were observed among dietary and/or muscle tissue FA with elovl2, fadsd5, and srebp1 transcript expression, further supporting FA biosynthesis. Significant relationships were also observed among lipid and cholesterol metabolism-related genes with dietary and tissue sterol and 20:4n−6 content, and they were most often related to cholesterol catabolism (or reduction in synthesis), such as hmgcr, dhcr7, and pparβ1. Correlations among gene expression with dietary and tissue lipid classes and FA content provided evidence to support the link between dietary FA input and phenotypic response.

Profiling and Metabolism of Sterols in the Weaver Ant Genus Oecophylla

Sterols are essential to insects because they are vital for many biochemical processes, nevertheless insects cannot synthesize sterols but have to acquire them through their diet. Studies of sterols in ants are sparse and here the sterols of the weaver ant genus Oecophylla are identified for the first time. The sterol profile and the dietary sterols provided to a laboratory Oecophylla longinoda colony were analyzed. Most sterols originated from the diet, except one, which was probably formed via dealkylation in the ants and two sterols of fungal origin, which likely originate from hitherto unidentified endosymbionts responsible for supplying these two compounds. The sterol profile of a wild Oecophylla smaragdina colony was also investigated. Remarkable qualitative similarities were established between the two species despite the differences in diet, species, and origin. This may reflect a common sterol need/aversion in the weaver ants. Additionally, each individual caste of both species displayed unique sterol profiles.

Anti-atherogenic effects of phytosteryl oleates in apo-E deficient mice

Both dietary oleic acid and plant sterols are known to reduce the risk of cardiovascular disease. We have produced phytosteryl oleates through enzymatic reactions. Cardiovascular benefits of phytosteryl oleates were investigated in apolipoprotein E knockout (apo E-KO) mice over 7 weeks at an oral dose of 2% (w/w). The mice treated with phytosteryl oleates had significantly lower very-low-density lipoprotein-cholesterol (VLDL-C) and higher high-density lipoprotein-cholesterol (HDL-C) concentrations as compared to the control group. The treated group also had significantly higher levels of cholesterol, campesterol and sitosterol in faecal materials as compared to the control group. These changes were accompanied by significant reductions in the volume of atherosclerotic lesions in the aortic roots. Furthermore, histological and biochemical analysis of hepatic tissues showed comparable data between the 2 groups of mice. This plus comparable body weight gain suggest a higher degree of safety and tolerability for phytosteryl oleates over 7 weeks of experimentation in this animal model. The data so obtained suggest a strong anti-atherogenic activity for phytosteryl oleates in apo E-KO mice. Additional studies are needed to confirm such effects over a longer period of time in this and other relevant animal models.

Effects of Dietary Plant Sterols and Stanol Esters with Low- and High-Fat Diets in Chronic and Acute Models for Experimental Colitis.

In this study, we evaluated the effects of dietary plant sterols and stanols as their fatty acid esters on the development of experimental colitis. The effects were studied both in high- and low-fat diet conditions in two models, one acute and another chronic model of experimental colitis that resembles gene expression in human inflammatory bowel disease (IBD). In the first experiments in the high fat diet (HFD), we did not observe a beneficial effect of the addition of plant sterols and stanols on the development of acute dextran sulphate sodium (DSS) colitis. In the chronic CD4CD45RB T cell transfer colitis model, we mainly observed an effect of the presence of high fat on the development of colitis. In this HFD condition, the presence of plant sterol or stanol did not result in any additional effect. In the second experiments with low fat, we could clearly observe a beneficial effect of the addition of plant sterols on colitis parameters in the T cell transfer model, but not in the DSS model. This positive effect was related to the gender of the mice and on Treg presence in the colon. This suggests that especially dietary plant sterol esters may improve intestinal inflammation in a T cell dependent manner.