Sarter B, Kelsey KS, Schwartz TA, Harris WS (2015) Clin Nutr. 34(2) 212-8 doi: 10.1016/j.clnu.2014.03.003. Epub 2014 Mar 14.
Several studies have demonstrated that vegetarians and vegans have much lower plasma concentrations of omega-3 fatty acids(i.e., docosahexaenoic and eicosapentaenoic acids) when compared to those who eat fish. The purposes of this study were 1) to define the age and/or sex-specific docosahexaenoic plus eicosapentaenoic acids levels in red blood cell membranes (expressed as a percent of total fatty acids; hereafter the omega-3 index) in long-term vegans, and 2) to determine the effects of a vegetarian omega-3 supplement (254 mg docosahexaenoic plus eicosapentaenoicacids/day for 4 months) on the omega-3 index.
A sample (n = 165) of vegans was recruited, and their omega-3 index was determined using a dried blood spot methodology. A subset of 46 subjects with a baseline omega-3 index of <4% was given a vegetarian omega-3 supplement for 4 months and then retested.
The mean ± SD omega-3 index was 3.7 ± 1.0% which was similar to that of a cohort of omnivores (deployed US soldiers) from a recently-reported study. Among the vegan cohort, the index was significantly higher in females than males (3.9 ± 1.0% vs. 3.5 ± 1.0%; p = 0.026) and was directly related to age (p for trend = 0.009). The omega-3 index increased from 3.1 ± 0.6% to 4.8 ± 0.8% (p = 0.009) in the supplementation study.
We conclude that vegans have low baseline omega-3 levels, but not lower than omnivores who also consume very docosahexaenoic and eicosapentaenoic acids. The vegans responded robustly to a relatively low dose of vegetarian omega-3 supplement.