Omega-3 and non-fish eaters
The human body can convert the essential fatty acid alpha-linolenic acid (ALA) to the longer chain eicosapentaenoic acid (EPA) and docosaexaenoic acid (DHA), which have been associated with several health benefits including the improvement of cardiovascular health.
The conversion from ALA to these omega-3 PUFAs involves enzymes such as desaturases and elongases. The conversion rate is small, since only between 8 and 20% of ALA is converted to EPA and between 0.5 and 9% to DHA. This is why it is strongly recommended to obtain EPA and DHA from dietary fish and fish oils and so, people who do not eat fish or fish oil may be at risk of having low levels of these PUFAs.
However, a recent study conducted by researchers from the University of East Anglia in England, showed that blood levels of EPA and DHA in vegans and vegetarians were similar to those of regular fish-eaters. The results suggested that despite vegans and vegetarians had lower intakes of omega-3 compared to fish-eaters, their plasma levels of DHA and EPA were similar to the levels of fish-eaters, showing only a slight decrease in the non-fish-eating levels.
These results may be explained by an increased conversion of the plant-derived ALA to omega-3 PUFAs that takes place when non-fish-eaters do not consume the recommended levels of EPA and DHA through a fish-rich diet.
In conclusion, it was observed than even though there were large differences in the dietary intake of omega-3 PUFAs, the differences in plasma were smaller than what was expected, suggesting that the best conversion rates were found in non-DHA and EPA consumers.
Source:
- “Dietary intake and status of n–3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of {alpha}-linolenic acid to long-chain n–3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort1,2,3. A.A. Welch, S. Shakya-Shrestha, M.A.H. Lentjes, N.J. Wareham, K-T. Khaw. American Journal of Clinical Nutrition, November 2010, Volume 92, Number 5, Pages 1040-1051, doi:10.3945/ajcn.2010.29457.
