Key Findings:
For many who do not eat fish as well as concerns with depleting marine resources, there is increasing interest in determine if adequate n-3 PUFA status can be achieved through conversion of plant-derived ALA. Some research has shown that although non-fish-eating meat-eaters and vegetarians have lower intakes of EPA and DHA than do fish-eaters, their n-3 PUFA status is higher than would be expected. Using data from 14,422 men and women aged 39–78 y in the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk cohort, the relationship between dietary ALA and circulating long-chain n-3 PUFAs was determined with 7-d diary data and a substudy in 4902 individuals with plasma phospholipid fatty acid measures. Although the estimated dietary intake of n-3 PUFAs in non-fish-eaters was only between 57% and 80% of that of fish-eaters, the differences between these groups were smaller for plasma n-3 PUFA status. Data from the precursor-product ratio from plant derived ALA to circulating LC n-3 PUFAs was significantly greater in non-fish-eaters than in those who ate fish. LC n-3 PUFA: ALA ratio was higher in women than in men, which indicated a greater estimated conversion from dietary ALA. A greater LC n-3 PUFA:ALA ratio was noted in non-fish-eaters than in fish-eaters suggesting a higher estimated conversion.
ABSTRACT:
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 alpha-linolenic acid (ALA) to EPA and DHA is debated. 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. 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 precursor product ratio of ALA to circulating n-3 PUFAs was calculated. 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 were 57–80% lower in non-fish eaters than in fish-eaters, but status differences were considerably smaller. The estimated precursor-product ratio was greater in women than in men and greater in non-fish-eaters than in fish-eaters. 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 precursor-product ratio 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. (Author`s abstract)