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 product-precursor ratio [corrected] of α-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort.


Authors AA Welch, S Shakya-Shrestha , MA Lentjes, NJ Wareham, KT Khaw
Institution School of Medicine Health Policy and Practice, University of East Anglia, Norwich, UK
Publication Name American Journal of Clinical Nutrition
Publication Date March 2011

BACKGROUND:
Intakes of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) are important for health. Because fish is the major source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), non-fish-eaters may have suboptimal n-3 PUFA status, although the importance of the conversion of plant-derived α-linolenic acid (ALA) to EPA and DHA is debated.
OBJECTIVE:
The objective was to determine intakes, food sources, and status of n-3 PUFAs according to dietary habit (fish-eaters and non-fish-eating meat-eaters, vegetarians, or vegans) and estimated conversion between dietary ALA and circulating long-chain n-3 PUFAs.
DESIGN:
This study included 14,422 men and women aged 39-78 y from the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk cohort with 7-d diary data and a substudy in 4902 individuals with plasma phospholipid fatty acid measures. Intakes and status of n-3 PUFAs were measured, and the product-precursor ratio [corrected] of ALA to circulating n-3 PUFAs was calculated.
RESULTS:
Most of the dietary intake of EPA and DHA was supplied by fish; however, meat was the major source in meat-eaters, and spreading fats, soups, and sauces were the major sources in vegetarians. Total n-3 PUFA intakes in non-fish-eaters were 57-80% of those in fish-eaters, but status differences were considerably smaller [corrected]. The estimated product-precursor ratio [corrected] was greater in women than in men and greater in non-fish-eaters than in fish-eaters.
CONCLUSIONS:
Substantial differences in intakes and in sources of n-3 PUFAs existed between the dietary-habit groups, but the differences in status were smaller than expected, possibly because the product-precursor ratio [corrected] was greater in non-fish-eaters than in fish-eaters, potentially indicating increased estimated conversion of ALA. If intervention studies were to confirm these findings, it could have implications for fish requirements.

Drew Ramsey, MD

Drew Ramsey, M.D. is a psychiatrist, author, and farmer. He is a clear voice in the mental health conversation and one of psychiatry’s leading proponents of using nutritional interventions. He is an assistant clinical professor of psychiatry at Columbia University College of Physicians and Surgeons.

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