Increasing Dietary α-Linolenic Acid Enhances Tissue Levels of Long-Chain n-3 PUFA when Linoleic Acid Intake Is Low in Hamsters

Abstract

Background/Aims: We tested whether feeding hamsters diets varying in α-linolenic acid (ALA) content and low in linoleic acid (LA) could increase the tissue levels of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) to the same extent as a fish oil-supplemented diet. Methods: For 5 weeks, 60 hamsters were fed 1 of the following 5 diets containing 2% of total dietary energy (TE) as LA and either 0.5% (diet A), 1% (diets B and E), 2% (diet C), or 4% (diet D) ALA of TE, so that the ratio of LA/ALA was 4:1, 2:1, 1:1, or 1:2. Diet E was supplemented with fish oil at the level of 0.2% of total energy intake. At the end of the study, overnight-fasted hamsters were sacrificed, and blood and tissues were collected. Results: Tissue levels of ALA, EPA, DPA, and DHA rose in proportion to the increase in the dietary ALA level (p < 0.01); however, the levels of DHA reached a plateau at ALA intakes above 1% (p < 0.01). These changes were accompanied by decreases in arachidonic acid with or without increases in LA levels (p < 0.01). Hamsters fed diet D had similar or higher EPA, DPA, and DHA tissue levels to those fed diet E (p < 0.01). Conclusions: In hamsters, diets containing 4% energy as ALA and 2% energy as LA can increase the tissue levels of EPA, DPA, and DHA to the same extent as feeding 0.2% energy as fish oil.