Trans fatty acids insulin resistance and diabetes

The possible relationship between consumption of trans fatty acids (TFAs) and risk of insulin resistance or development of diabetes mellitus type II has been considered by a number of human and animal studies over the past decade. This review evaluates the evidence, and concludes that there is limited evidence for a weak association at high TFA intakes, but very little convincing evidence that habitual exposure as part of a standard western diet has a significant contribution to risk of diabetes or insulin resistance. The possibility of increased risk for individuals with particular genotypes (such as the FABP2 Thr54 allele) is of interest, but further work would be required to provide sufficient evidence of any association.

Speciation and variation in the occurrence of haloacetic acids in three water supply systems in England

An investigation into the speciation and occurrence of nine haloacetic acids (HAAs) was conducted during the period of April 2007 to March 2008 and involved three drinking water supply systems in England, which were chosen to represent a range of source water conditions; these were an upland surface water, a lowland surface water and a groundwater. Samples were collected seasonally from the water treatment plants and at different locations in the distribution systems. The highest HAA concentrations occurred in the upland surface water system, with an average total HAA concentration of 21.3 μg/L. The lowest HAA levels were observed in the groundwater source, with a mean concentration of 0.6 μg/L. Seasonal variations were significant in the HAA concentrations; the highest total HAA concentrations were found during the autumn, when the concentrations were approximately two times higher than in winter and spring. HAA speciation varied among the water sources, with dichloroacetic acid and trichloroacetic acid dominant in the lowland surface water system and brominated species dominant in the upland surface water system. There was a strong correlation between trihalomethanes and HAAs when considering all samples from the three systems in the same data set (r2=0.88); however, the correlation was poor/moderate when considering each system independently.

Effect of intensive vs. free range production on the fat and fatty acid composition of whole birds and edible portions of retail chickens in the UK

The primary objective was to compare the fat and fatty acid contents of cooked retail chickens from intensive and free range systems. Total fat comprised approximately 14, 2.5, 8, 9 and 15 g/100 g cooked weight in whole birds, skinless breast, breast with skin, skinless leg and leg meat with skin, respectively, with no effect of intensive compared with free range systems. Free range breast and leg meat contained significantly less polyunsaturated fatty acids (n-6 and n-3) than did those from intensive rearing and had a consistently higher n-6/n-3 ratio (6.0 vs. 7.9). Generally, the concentrations of long chain n-3 fatty acids were considerably lower than those reported in earlier research studies. Overall, there was no evidence that meat from free range chickens had a fatty acid profile that would be classified as healthier than that from intensively reared birds and indeed, in some aspects, the opposite was the case. (C) 2011 Elsevier Ltd. All rights reserved.

Dietary monounsaturated fatty acids and haemostasis

Diets high in monounsaturated fatty acids (MUFA) are increasingly being recommended as a highly-effective cholesterol-lowering strategy in populations at risk of CHD. However, the need for a re-appraisal of the benefits of diets rich in MUFA became apparent as a result of recent studies showing that meals high in olive oil cause greater postprandial activation of blood coagulation factor VII than meals rich in saturated fatty acids. The present review evaluates the evidence for the effects of MUFA-rich diets on fasting and postprandial measurements of haemostasis, and describes data from a recently-completed long-term controlled dietary intervention study. The data show that a background diet high in MUFA has no adverse effect on fasting haemostatic variables and decreases the postprandial activation of factor VII in response to a standard fat-containing meal. Since the same study also showed a significant reduction in the ex vivo activation of platelets in subjects on the high-MUFA diet, the overall findings suggest that there is no reason for concern regarding adverse haemostatic consequences of high-MUFA diets.

Dietary fatty acids and human health

A considerable amount of evidence has accumulated to support the view that the very long chain omega 3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) have beneficial cardiovascular and anti-inflammatory properties and that levels of their consumption are insufficient in most Western diets. More recently, attention has been given to the possibility that the precursor omega-3 PUFA, alpha linolenic acid (ALNA), may share some of the beneficial actions of EPA/DHA on human health. Further research into the metabolism and physiological actions of ALNA, and comparisons with EPA/DHA, is needed before conclusions regarding the optimal amounts and types of omega-3 PUFA for human health can be defined. Conjugated linoleic acid (CLA), which arises as a metabolic by-product of rumen hydrogenation and which is found in foods of animal origin, has been proposed to possess potent health promoting properties, but much of this research has been conducted in experimental animals. There is an urgent need for complementary studies in human volunteers, to confirm the putative anti-carcinogenic, anti-atherogenic, anti-lipogenic and immuno-suppressive properties of CLA.

Dietary interventions affecting chylomicron and chylomicron remnant clearance

Interest in effects of diet on postprandial lipoproteins has increased in recent years as a result of accumulating evidence for adverse cardiovascular consequences of elevated concentrations of triglyceride rich lipoproteins. Particular attention has been given to ability of different fatty acids to modulate postprandial lipoprotein responses because of evidence for both harmful and protective cardiovascular properties of the saturated, monounsaturated and ω-6 and ω-3 polyunsaturated fatty acid (PUFA) classes. Evidence for direct atherogenic properties of chylomicron remnants has led to attempts to monitor effects of diet specifically on this lipoprotein class. Limitations in the methods employed to measure chylomicron remnants and the small number of human studies which have evaluated effects of meal, and background diet, fatty acid composition, makes it difficult to draw definitive conclusions at the present time. However consideration of data from both animal and human studies tends to support the conclusion that diets, and meals, rich in PUFA (particularly long chain ω-3 PUFA), result in attenuated postprandial responses of the intestinally-derived lipoproteins. Attenuated responses to high PUFA meals appear to be due to greater rates of clearance and greater activation of lipoprotein lipase (LPL). Attenuated responses to high PUFA background diets may be due to adaptive changes involving both accelerated rates of clearance in peripheral tissues and liver, as well as decreased output of the competitor for chylomicron clearance, very low density lipoprotein (VLDL).

Peptidomimetic design of unusual turns by incorporating flexible and rigid omega-amino acids simultaneously

The tripeptides Boc-Gly-Aib-m-ABA-OMe (I), Boc-beta Ala-Aib-m-ABA-OMe (II) and Boc-gamma Abu-Aib-rn-ABA-OMe (III) (Aib: alpha-aminoisobutyric acid, beta Ala: beta-alanine, gamma Abu: gamma-aminobutyric acid, m-ABA: meta-aminobenzoic acid) with homologated amino acids at the N-terminus, the rigid gamma-amino acid m-ABA at the C-terminus and the helicogenic Aib at the central position have been chosen to create unusual turns. Single crystal X-ray diffraction studies, solvent dependent NMR titrations and 2D NMR analysis reveal that peptides II and III adopt unusual turns of 11- and 12-membered rings stabilized by modified 4 -> 1 type intramolecular hydrogen bonds. Solution phase studies indicate that peptide I exists in the beta-turn conformation stabilized by 10-membered intramolecular hydrogen bonding.

Genetic predisposition influences plasma lipids of participants on habitual diet, but not the response to reductions in dietary intake of saturated fatty acids

Objective: SNPs identified from genome wide association studies associate with lipid risk markers of cardiovascular disease. This study investigated whether these SNPs altered the plasma lipid response to diet in the ‘RISCK’ study cohort. Methods: Participants (n = 490) from a dietary intervention to lower saturated fat by replacement with carbohydrate or monounsaturated fat, were genotyped for 39 lipid-associated SNPs. The association of each individual SNP, and of the SNPs combined (using genetic predisposition scores), with plasma lipid concentrations was assessed at baseline, and on change in response to 24 weeks on diets. Results: The associations between SNPs and lipid concentrations were directionally consistent with previous findings. The genetic predisposition scores were associated with higher baseline concentrations of plasma total(P = 0.02) and LDL (P = 0.002) cholesterol, triglycerides (P = 0.001) and apolipoprotein B (P = 0.004), and with lower baseline concentrations of HDL cholesterol (P < 0.001) and apolipoprotein A-I (P < 0.001). None of the SNPs showed significant association with the reduction of plasma lipids in response to the dietary interventions and there was no evidence of diet-gene interactions. Conclusion: Results from this exploratory study have shown that increased genetic predisposition was associated with an unfavourable plasma lipid profile at baseline, but did not influence the improvement in lipid profiles by the low-saturated-fat diets.

Chronic disease risk associated with different dietary saturated fatty acids

This chapter compares the risks of chronic disease, and cardiovascular disease in particular, associated with consumption of different saturated fatty acids. Emphasis is placed on the effects of stearic acid as this has potential to replace trans fatty acids in certain manufactured food products. The chapter first reviews the effects of individual saturated fatty acids on blood lipids, including cholesterol, as these are commonly used as markers of disease risk. It then looks directly at evidence in relation to health outcomes. Finally, recent evidence specifically on the effect of stearic acid relative to other fatty acids, including trans fatty acids, is summarised.

Effects of dietary polyunsaturated fatty acid supplementation on fatty acid composition in muscle and subcutaneous adipose tissue of lambs

Lambs (n = 48) were used in a 2 × 2 factorial arrangement of treatments to evaluate effects of inclusion of oil containing PUFA in high-concentrate diets (with or without) and duration of oil supplementation (pre- vs. postweaning) on CLA concentration of muscle and adipose tissue. Lambs were fed preweaning creep diets (with or without oil) corresponding to the dietary lactation treatment diet (with or without oil) of the dam. Dams blocked by lambing date and rearing type were randomly assigned to 1 of 2 lactation dietary treatments with or without oil supplementation. Creep diets contained approximately 70% concentrate and 30% roughage and were provided to lambs for ad libitum intake. At weaning (58.7 ± 2.5 d of age), lambs (n = 48) were randomly assigned within preweaning treatment groups to 1 of 2 postweaning dietary treatments (with or without oil) and 16 pens in a randomized block design, blocked by sex and BW. Postweaning diets were formulated to contain approximately 80% concentrate and 20% roughage and were fed once daily for ad libitum intake. Soybean and linseed oil (2:1, respectively) replaced ground corn and provided 3% additional fat in pre- and postweaning diets. Lambs were slaughtered at 60.3 ± 4.2 kg of BW. A subcutaneous fat (SQ) sample was obtained within 1 h postmortem and a LM sample at the 12th rib was obtained 24 h postmortem, and both were analyzed for fatty acid profile. Feedlot performance and carcass measurements were not affected (P ≥ 0.26) by oil supplementation. Total CLA content of LM and SQ was not affected (P ≥ 0.08) by oil supplementation pre- or postweaning, but trans-10, cis-12 CLA was greater (P = 0.02) in SQ from lambs supplemented with oil postweaning. Total PUFA content in LM was greater (P = 0.02) in lambs supplemented with oil pre- or postweaning as a result of increased concentrations of 18:2cis-9, cis-12 and longer chain PUFA. Conversely, pre- and postweaning oil supplementation resulted in less (P = 0.04) MUFA content in LM. Only postweaning oil supplementation increased (P = 0.001) SQ PUFA content. Feeding oils containing PUFA to lambs pre- and postweaning did not increase CLA content of muscle, whereas postweaning oil supplementation minimally increased CLA concentration of SQ fat. Inclusion of soybean and linseed oil in pre- and postweaning diets increased total PUFA content of SQ fat and muscle tissue without adversely affecting growth performance or carcass characteristics.