The Effects of Linoleic Acid Consumption on Lipid Risk Markers for Cardiovascular Disease in Healthy Individuals: A Review of Human Intervention Trials.

Cardiovascular disease (CVD) is the leading cause of death worldwide. Risk factors for developing this disease include high serum concentrations of total cholesterol, triglycerides, low-density lipoproteins, very-low density lipoproteins, and low concentrations of high-density lipoproteins. One proposed dietary strategy for decreasing risk factors involves replacing a portion of dietary saturated fatty acids with mono- and polyunsaturated fatty acids (PUFAs). The essential omega-6 PUFA, linoleic acid (LA), is suggested to decrease the risk for CVD by affecting these lipid risk markers. Reviewing human intervention trials will provide further evidence of the effects of LA consumption on risk factors for CVD. PubMed was used to search for peer-reviewed articles. The purpose of this review was: (1) To summarize human intervention trials that studied the effects of LA consumption on lipid risk markers for CVD in healthy individuals, (2) to provide mechanistic details, and (3) to provide recommendations regarding the consumption of LA to decrease the lipid risk markers for CVD. The results from this review provided evidence that LA consumption decreases CVD lipid risk markers in healthy individuals.

Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?

Good sources of the long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) include cold-water fish and seafood; however, vegan diets (VGNs) do not include animal-origin foods. Typically, US omnivores obtain enough dietary EPA and DHA, but unless VGNs consume algal n-3 supplements, they rely on endogenous production of long-chain fatty acids. VGN diets have several possible concerns: (1) VGNs have high intakes of linoleic acid (LA) as compared to omnivore/non-vegetarian diets. (2) High intakes of LA competitively interfere with the endogenous conversion of alpha-linolenic acid (ALA) to EPA and DHA. (3) High somatic levels of LA/low ALA indicate a decreased ALA conversion to EPA and DHA. (4) Some, not all VGNs meet the Dietary Reference Intake Adequate Intake (DRI-AI) for dietary ALA and (5) VGN diets are high in fiber, which possibly interferes with fat absorption. Consequently, health professionals and Registered Dietitians/Registered Dietitian Nutritionists working with VGNs need specific essential fatty acid diet guidelines. The purpose of this review was: (1) to suggest that VGNs have a DRI-AI Special Consideration requirement for ALA and LA based on VGN dietary and biochemical indicators of status and (2) to provide suggestions to ensure that VGNs receive adequate intakes of LA and ALA.

Egg n-3 fatty acid composition modulates biomarkers of choline metabolism in free-living lacto-ovo-vegetarian women of reproductive age.

The lacto-ovo-vegetarian (LOV) dietary regimen allows eggs, which are a rich source of choline. Consumption of eggs by LOV women may be especially important during pregnancy and lactation when demand for choline is high. The aim of this single blind, randomized, crossover-feeding study was to determine how near-daily egg consumption influenced biomarkers of choline metabolism in healthy LOV women of reproductive age (n=15). Because long-chain n-3 fatty acids could influence choline metabolism, the effect of n-3-enriched vs nonenriched eggs on choline metabolites was also investigated. Three 8-week dietary treatments consisting of six n-3-enriched eggs per week, six nonenriched eggs per week, and an egg-free control phase were separated by 4-week washout periods. Choline metabolites were quantified in fasted plasma collected before and after each treatment and differences in posttreatment choline metabolite concentrations were determined with linear mixed models. The n-3-enriched and nonenriched egg treatments produced different choline metabolite profiles compared with the egg-free control; however, response to the eggs did not differ (P>0.1). Consumption of the n-3-enriched egg treatment yielded higher plasma free choline (P=0.02) and betaine (P<0.01) (vs egg-free control) concentrations, whereas consumption of the nonenriched egg treatment yielded borderline higher (P=0.06) plasma phosphatidylcholine (vs egg-free control) levels. Neither egg treatment increased levels of plasma trimethylamine oxide, a gut-flora-dependent oxidative choline metabolite implicated as a possible risk factor for cardiovascular disease. Overall these data suggest that egg fatty-acid composition modulates the metabolic use of choline.

Effects of supplementing n-3 fatty acid enriched eggs and walnuts on cardiovascular disease risk markers in healthy free-living lacto-ovo-vegetarians: a randomized, crossover, free-living intervention study.

BACKGROUND: Plant and marine n-3 fatty acids (FA) may favorably modify select markers of cardiovascular disease risk. Whether supplementing the habitual diet of lacto-ovo-vegetarians (LOV) with walnuts (containing α-linolenic acid, ALA) and n-3 FA enriched eggs (containing primarily docosahexaenoic acid, DHA and ALA) would have equivalent effects on CVD risk factors is explored in this study. METHODS: In this study, 20 healthy free-living LOVs following their habitual diet were randomly assigned in a crossover design to receive one of three supplements: n-3 FA enriched egg (6/week), walnuts (28.4 g, 6/week) or a standard egg, 6/week (control) for 8 weeks each with 4-wk washout between treatments. Erythrocyte membrane fatty acids, serum lipids and inflammatory markers were measured at the end of each treatment. RESULTS: Dietary compliance was observed by an expected increase in erythrocyte membrane ALA following the walnut treatment and in DHA following the n-3 FA enriched egg treatment. Walnut treatment lowered serum triacylglycerol, total cholesterol and Apo B (p < 0.05) compared to the standard egg but not the n-3 FA enriched egg treatment. However, walnut treatment significantly reduced total: HDL cholesterol ratio compared to both egg treatments. There were no differences between treatments for any of the inflammatory markers. CONCLUSIONS: For LOV, a direct source of DHA such as n-3 FA enriched eggs seems necessary to increase membrane levels of DHA. However for producing an overall favorable blood lipid profile, daily consumption of a handful of walnuts rich in ALA may be a preferred option for lacto-ovo vegetarian.

Effects of fish oil supplementation on inflammatory acne.

BACKGROUND: Given that acne is a rare condition in societies with higher consumption of omega-3 (n-3) relative to omega-6 (n-6) fatty acids, supplementation with n-3 may suppress inflammatory cytokine production and thereby reduce acne severity. METHODS: 13 individuals with inflammatory acne were given three grams of fish oil containing 930 mg of EPA to their unchanged diet and existing acne remedies for 12 weeks. Acne was assessed using an overall severity grading scale, total inflammatory lesion counts, and colorimetry. FINDINGS: There was no significant change in acne grading and inflammatory counts at week 12 compared to baseline. However, there was a broad range of response to the intervention on an individual basis. The results showed that acne severity improved in 8 individuals, worsened in 4, and remained unchanged in 1. Interestingly, among the individuals who showed improvement, 7 were classified as having moderate to severe acne at baseline, while 3 of the 4 whose acne deteriorated were classified as having mild acne. CONCLUSION: There is some evidence that fish oil supplementation is associated with an improvement in overall acne severity, especially for individuals with moderate to severe acne. Divergent responses to fish oil in our pilot study indicates that dietary and supplemental lipids are worthy of further investigation in acne.