Alpha-linolenic Acid- and Docosahexaenoic Acid-Enriched Eggs from Hens Fed Flaxseed: Influence on Blood Lipids and Platelet Phospholipid Fatty Acids in Humans.
Alpha-linolenic Acid- and Docosahexaenoic Acid-Enriched Eggs from Hens Fed Flaxseed: Influence on Blood Lipids and Platelet Phospholipid Fatty Acids in Humans.
Year: 1995
Authors: L K Ferrier, L J Caston, S Leeson, J Squires, B J Weaver, B J Holub.
Publication Name: Am. J. Clin. Nutr.
Publication Details: Volume 62; Page 81
Abstract:
Clinical and epidemiological evidence has established that dietary n-3 PUFA consumption is associated with reduced risk of cardiovascular disease and all-cause mortality. The effects of n-3 PUFA are due to their ability to lower serum lipid levels and alter the production of inflammatory and aggregatory eicosanoids. The typical Western style diet is often deficient in sources of n-3 FAs which are commonly found in fatty fish and fish oils. In 1990, Health and Welfare Canada set recommended intakes for dietary ALA as 0.5% of energy. A ratio between 4:1 and 10:1 was recommended for n-6 to n-3 fatty acids. However, these recommendations are currently not being met by the overall population. ALA from flaxseed can serve as a precursor for EPA and DHA and also has serum lipid lowering effects which are independent of its conversion to these longer chain PUFAs. Thus, efforts have been directed toward increasing the levels of n-3 PUFAs in animal products through the feeding of rations rich in flaxseed. In this study, the effects of the consumption of eggs from hens fed diets containing flaxseed on plasma and platelet lipids of male volunteers were assessed. Initially, diets containing 0%, 10% and 20% ground flaxseed were fed to hens in order to increase overall n-3 FAs. These diets resulted in a marked progressive increase in n-3 fatty acid content as ALA (28, 261, and 527 mg/egg) and DHA (51, 81, and 87 mg/egg). No alterations in the cholesterol concentration of the egg yolk were noted. Twenty-eight normocholesterolemic male volunteers were subsequently divided into three groups and were fed four eggs per day for 2 weeks according to a cyclic Latin-square design. Group 1 consumed control eggs, group 2 were fed 10% flaxseed eggs and group 3 consumed 20% FS eggs. The eggs were added to the typical diets of the subjects who were also advised to consume little canola oil, fish or fish oil, flaxseed or flaxseed oil or regular eggs. Following the dietary treatment period, no statistically significant changes were observed in TC, HDL-C, or plasma TG concentrations. However, significant increases in PL total n-3 fatty acids and in DHA content (which rose from 1.5 to 2.0% by wt or 33% overall) were found. The elevation in DHA may have resulted from conversion of ALA and/or directly from the DHA found in the eggs. In addition, a significant decrease in the ratio of n-6 to n-3 fatty acids were found in platelet PLs of subjects consuming eggs from FS-fed hens. DHA has been shown in vitro to reduce platelet aggregation. Excessive platelet aggregation can lead to arterial thrombosis. DHA as well as reduced platelet PL n-6 PUFAs are associated with lower aggregation and risk of coronary heart disease. Thus, an accumulation of DHA at the expense of n-6 PUFAs in platelet PLs may provide protection against heart disease. The authors concluded that eggs modified by the inclusion of flaxseed in the laying hens’ diet could provide an important nutritional source of n-3 PUFAs. Further, the authors indicate that one flaxseed enriched egg would provide 261 mg (10% FS diet) or 527 mg (20% FS diet) of ALA which translates into 24% and 48%, respectively, of the daily requirement for women and 17% and 35%, respectively of the requirement for men. The consumption of such eggs would significantly increase the availability of ALA and DHA in the typical Western style diet.
