The effect on human tumor necrosis factor α and interleukin 1β production of diets enriched in n-3 fatty acids from vegetable oil or fish oil

The effect of a flaxseed oil-based diet on tumor necrosis factor α (TNFα) and interleukin 1β (IL-1β) synthesis was examined in healthy volunteers. Use of flaxseed oil in domestic food preparation for 4 wk inhibited TNFα and IL-1β production by ≃30%. Fish-oil supplementation (9 g/d) continued for a further 4 wk; TNFα and IL-1β synthesis were inhibited by 74% and 80%, respectively. There was a significant inverse exponential relation between TNFα or IL-1β synthesis and mononuclear cell content of eicosapentaenoic acid (EPA), an n=3 fatty acid derived from ingested EPA (fish oil) or metabolism of ingested α-linolenic acid (flaxseed oil). Cytokine production decreased as cellular EPA increased to ≃1% of total fatty acids. Further increases in EPA content did not result in further decreases in cytokine production. The results indicate that vegetable oils rich in n=3 fatty acids inhibit TNFα and IL-1β synthesis.