Increasing Dietary Linoleic Acid Does Not Increase Tissue Arachidonic Acid Content in Adults Consuming Western- Type Diets

Linoleic acid, with a DRI of 12-17g/d, is the most highly consumed polyunsaturated fatty acid in the Western diet and is found in virtually all commonly consumed foods. The concern with dietary linoleic acid, being the metabolic precursor of arachidonic acid, is its consumption may enrich tissues with arachidonic acid and contribute to chronic and overproduction of bioactive eicosanoids. However, no systematic review of human trials regarding linoleic acid consumption and subsequent changes in tissue levels of arachidonic acid has been undertaken. In this study, we reviewed the human literature that reported changes in dietary linoleic acid and its subsequent impact on changing tissue arachidonic acid in erythrocytes and plasma/serum phospholipids. We identified, reviewed, and evaluated all peer-reviewed published literature presenting data outlining changes in dietary linoleic acid in adult human clinical trials that reported changes in phospholipid fatty acid composition (specifically arachidonic acid) in plasma/serum and erythrocytes within the parameters of our inclusion/exclusion criteria. Decreasing dietary linoleic acid up to 90% was not significantly correlated with changes in tissue arachidonic acid levels (p=0.39). Similarly, when dietary linoleic acid levels were increased six fold, no significant correlations with tissue arachidonic acid levels were observed (p=0.72). However, there was a positive relationship between dietary gamma-linolenic acid and arachidonic acid on changes in tissue arachidonic levels. Our results do not support the concept that modifying current intakes of dietary linoleic acid has an effect on changing tissue levels of arachidonic acid in adults consuming Western-type diets.