BACKGROUND: Data on EPA and DHA fatty acids in vegans (VGN) and vegetarians (LOV) are scarce. Also, the extent to which red blood cell (RBC) levels of these fatty acids (FAs) vary by dietary pattern and are correlated with dietary EPA+DHA intake is less well-known.
OBJECTIVES: The primary objective of this study was to compare RBC EPA and DHA content [i.e., the omega-3 index (O3I)] VGN, LOV, pesco-vegetarians (PV), and non-vegetarians (NV) in the Adventist Health Study II (AHS2). The secondary objective was to determine the extent to which the dietary intake of these PUFAs correlated with RBC levels.
METHODS: Participants (N = 300, 75 per diet group) were randomly selected from AHS2 cohort. After removing individuals reporting fish oil supplement use, 241 remained for analysis. Dietary data were collected via a validated questionnaire. RBCs were analyzed for FA composition by gas chromatography.
RESULTS: Mean O3I (±SD) O3I values across diet groups for VGNs, LOVs, PVs and NVs was 3.7 ± 1.1, 3.9 ± 1.3, 5.7 ± 2.1, and 5.0 ± 1.3, respectively, and EPA+DHA intakes (mg/d) were 10 ± 40, 18 ± 54, 158 ± 279, and 117 ± 91, respectively. EPA+DHA intake correlated strongly with the O3I (r = 0.67, p < 0.001). The dietary ratio of linoleic acid to alpha-linoleic acid was unrelated to the O3I, and the linoleic acid intake was not associated with RBC arachidonic acid levels.
CONCLUSIONS: VGNs and LOVs had O3I levels (and EPA+DHA intakes) well below recommended targets. For these groups, the most reasonable way to raise these levels is to consume algae-derived EPA+DHA supplements.