Linoleic Acid: A Nutritional Quandary.

Over the course of the twentieth century, there was a 20-fold increase in consumption of vegetable oils resulting both from their increased availability and from recommendations to consume these oils as an aid to lower blood cholesterol levels. This dietary change markedly increased the consumption of linoleic acid to current levels of approximately 6% of total dietary energy. While considerable research has focused on the effects of dietary linoleic acid on cardiovascular health, questions about optimum dietary levels remain. For example, meta-analyses disagree about the role of dietary linoleic acid in atherosclerosis, and recent publications indicate that linoleic acid's reduction of blood cholesterol levels does not predict its effect on the development of atherosclerosis. Further, there are also detrimental effects of elevated dietary linoleic acid on human health related to its role in inflammation and its activity as a promoter of cancer in animals. Current data do not allow determination of the level of dietary linoleic acid needed for optimum health. Studies of the effects of a wide range of linoleic acid consumption may help determine dietary recommendations that are optimal for human health.