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

Plant and marine n3 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 alpha 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. 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 per week), walnuts (28.4 g, 6 per week) or a standard egg, 6 per 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.  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 compared to the standard egg but not the n 3 FA enriched egg treatment. However, walnut treatment significantly reduced total oHDL cholesterol ratio compared to both egg treatments. There were no differences between treatments for any of the inflammatory markers. For LOV, a direct source of DHA such as n3 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. (Authors abstract)
Diets containing high amounts of both plant and marine derived n 3 fatty acids are associated with reduced risk of cardiovascular disease (CVD), but studies indicate Americans do not consume enough n   3 fatty acids. Some fortified dairy products and eggs contain very small amounts of DHA (0.02 to 0.3 g per serving) and are the only direct sources of DHA in the LOV diet. The only vegan DHA option is an algae based supplement. Vegans and LOVs depend on the endogenous production of EPA and DHA from ALA. The dietary ratio of n6 to n3 fatty acids influences conversion of ALA to EPA and DHA. While LOVs and vegans do consume significant amount of ALA in their diet, overall their linoleic acid (LA) intake is many folds higher than ALA intake producing high n6 to n3 fatty acid ratio. This may suppress the conversion of ALA to EPA and DHA.  Consumption of 57 to 71 g per day of ALA rich walnuts decreases total and LDL cholesterol (LDLC) and triacylglycerol (TAG) in normo and hypercholesterolemic individuals, resulting in a favorable reduction in CVD risk. Chickens fed flaxseed, soy, or algal marine sources, incorporate DHA and ALA into their eggs, which results in the production of n3 fatty acid enriched eggs. N3 fatty acid enriched eggs fed to hyper cholesterolemic non vegetarians showed increase in HDLC, decrease in platelet aggregation, and significant lowering of TAG. Some studies have looked at the effect of feeding n3 fatty acid enriched eggs on blood lipids, but none have compared the effects of ALA rich walnuts with that of n3 fatty acid (primarily DHA) enriched egg on CVD risk factors especially among LOVs.
LA and ALA were significantly higher during the walnut compared to the egg treatments. DHA was higher during the n3 fatty acid enriched egg compared to the standard egg and walnut treatment periods. EPA was not significantly different between treatments. There was also a slight decrease in monounsaturated fat in the walnut diet compared to the egg treatments. On the walnut treatment there was a significant decrease in total cholesterol, triglyceride and apo B, compared to the standard egg but not the n 3 fatty acid enriched egg treatment.  The total C to HDLC ratio was lower in the walnut treatment compared to both the egg treatments.  There were no significant differences among treatments in any of the inflammatory markers assessed In this study ALA rich walnuts and n 3 fatty acid enriched (primarily DHA) eggs were compared with a standard egg control with respect to their effects on select CVD risk factors among lacto ovo vegetarians (LOV). Adding about 24 g per d (1 ounce, 6 d per week) of walnuts to the habitual diet of LOV lowered total C and TAG compared to eating 6 standard eggs a week. More importantly, adding ALA rich walnuts to the habitual diet of LOV lowered the ratio of total to HDL cholesterol compared to both egg treatments, even when the egg contained a significant amount of DHA. The study suggests that for lacto ovo vegetarians, replacing standard eggs with n3 fatty acid enriched eggs in their diet may be an option to increase DHA content of erythrocyte membranes. (Editors coments)