Systematic review of the effect of dietary linoleic acid on changes of tissue levels of arachidonic acid and docosahexaenoic acid in humans

Linoleic acid (LA), with a DRI of 11–17g/d, is the most commonly consumed polyunsaturated fatty acid (PUFA) in the Western diet. The concern is that LA is the metabolic precursor of arachidonic acid (AA) and its consumption may enrich tissues with AA and contribute to chronic and overproduction of bioactive eicosanoids derived from AA. Similarly, there is a concern that dietary LA may interfere with the production and incorporation of the long chain n‐3 PUFA into tissues, in particular, docosahexaenoic acid (DHA). However, no systematic review of human trials regarding LA consumption and subsequent changes in tissue levels of AA or DHA has been undertaken. In this study, we systematically reviewed the human literature that reported changes in dietary LA and its subsequent impact on changing tissue AA and/or DHA in platelets, erythrocytes and plasma phospholipids. Decreasing dietary LA up to 90% failed to modify tissue AA levels (p=0.39). When dietary LA levels were increased 6 fold, no changes in tissue AA levels were observed (p=0.72). Similarly, decreasing (by 90%) or increasing (6 fold) dietary LA failed to modify tissue DHA levels (p=0.39 and p=0.55, respectively). Our results suggest that modifying current intakes of dietary LA have no effect on changing tissue levels of AA or DHA in adults. (Supported, in part, by the TN AES and in conjunction with USDA's NC‐1039 multistate research project).