Walnuts Improve Cholesterol but Fail to Increase DHA in Vegetarians
Previous research has shown that it takes at least 3.7 g of the short-chain omega-3 fatty acid, ALA, to increase DHA levels in vegetarians in the short term, with the longest trial lasting 6 weeks.
A new study from Loma Linda University (1) put a group of lacto-ovo vegetarians, average age of 38, on three different daily regimens for 8 weeks each:
– 1 oz of walnuts (3.0 g of ALA)
– 1 regular egg (110 mg DHA)
– 1 fortified egg (~500 mg DHA, 40 mg EPA, 1 g ALA)
The ratio of omega-6 to omega-3 was 6 to 1 in the walnut phase, which is relatively low for a vegetarian diet, but DHA levels did not increase. The ratio of total cholesterol to HDL was lower in the walnut treatment compared to both egg treatments and there were no significant differences for any inflammatory markers.
In conclusion, 8 weeks of 1 oz walnuts daily improved cholesterol markers but did not increase DHA levels.
I have updated Omega-3 Fatty Acid Recommendations for Vegetarians with this information.
1. Burns-Whitmore B, Haddad E, Sabaté J, Rajaram S. 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. Nutr J. 2014 Mar 27;13(1):29. | link