Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega 3 fatty acid supplement

January 1, 2014 Human Health and Nutrition Data 0 Comments

Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega 3 fatty acid supplement

Year: 2014
Authors: Sarter, B. Kelsey, K.S. Schwartz, T.A. Harris, W.S.
Publication Name: Clin Nutr.
Publication Details: Volume S0261-5614; Issue 14; Page 00076.4


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 were1) 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 eicosapentaenoic acids per day for 4 months) on the omega 3 index. A sample (n of 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 less than 4 per cent was given a vegetarian omega 3 supplement for 4 months and then retested. The mean plus SD omega 3 index was 3.7 plus 1.0 per cent 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 plus 1.0 per cent vs. 3.5 plus 1.0 per cent) and was directly related to age. The omega 3 index increased from 3.1 plus 0.6 per cent to 4.8 plus 0.8 per cent in the supplementation study. We conclude that vegans have low baseline omega 3 levels, but not lower than omnivores who also consume very little docosahexaenoic and eicosapentaenoic acids. The vegans responded robustly to a relatively low dose of a vegetarian omega 3 supplement. (Authors abstract)
It is possible that low omega 3 status does place vegetarians and vegans at increased risk for disease. There were 2 purposes of this study. The first (Phase 1) was to determine omega 3 status in long term vegans and to investigate age and or sex related differences. A vegan with an omnivore cohort was compared with respect to omega 3 status. Published data from omnivores who met most of the same inclusion and exclusion criteria as did the vegans was used.  The second purpose was to determine the extent to which omega 3 status can be improved in vegans by the administration of a vegan DHA þ EPA supplement (Phase 2). DHA and EPA content of red blood cells (RBC) expressed as a percent of total RBC fatty acids (hereafter called the omega 3 index), as the biomarker of omega 3 status was used. In long term vegans, assuming an omega 3 index of  less than 4 per cent to be undesirable, 64 per cent of the cohort fell into this category, 27 per cent were  less than 3 per cent and 1 per cent was  less than 2 per cent. An increase in the index was seen with age, which has been observed before in omnivore populations and has typically been explained by increased fish intake with aging. The inclusion of the ALA intake into the model suggests that increasing ALA intakes with age may have contributed to the correlation between age and the index. Whether the higher ALA intake was responsible for the higher omega 3 index cannot be known from these cross sectional observations. Women had higher omega 3 indexes than men. As a comparator population a group of 78 US service members (virtually all males) deployed in Iraq who were eating Army rations (not vegetarian cuisine) were used. EPA and DPA (the latter being an elongation product of the former) were both significantly higher in the vegans than in the soldiers, but DHA (and the omega 3 index) were not different. It appears that vegans are no different from omnivores who also consume very little omega 3. Based on this comparison, the vegans may even produce more EPA (and DPA), from their presumably higher ALA intake. 
In Phase 2, a relatively low dose of EPA plus DHA (243 mg per day) significantly raised the omega 3 index. The mean absolute increase here was 1.7 per cent over 4 months suggesting that vegans respond to supplemental omega 3 fatty acids in the same way that omnivores do.
The authors conclude that a majority of long term vegans appear to be relatively deficient in DHA and EPA, but whether this leads to adverse health consequences is unclear. It is possible that low dose supplementation with algae sourced DHA and EPA may mitigate the potential adverse effects of deficiency in this population. (Editors comments)

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