The role of dietary n-6 fatty acids in the prevention of cardiovascular disease.

Abstract

n-6 Fatty acids, like n-3 fatty acids, play essential roles in many biological functions. Because n-6 fatty acids are the precursors of proinflammatory eicosanoids, higher intakes have been suggested to be detrimental, and the ratio of n-6 to n-3 fatty acids has been suggested by some to be particularly important. However, this hypothesis is based on minimal evidence, and in humans higher intakes of n-6 fatty acids have not been associated with elevated levels of inflammatory markers. n-6 Fatty acids have long been known to reduce serum total and low-density lipoprotein cholesterol, and increases in polyunsaturated fat intake, mostly as n-6 fatty acids, were a cornerstone of dietary advice during the 1960s and 1970s. In the United States, for example, intake of n-6 fatty acids doubled and coronary heart disease (CHD) mortality fell by 50% over a period of several decades. In a series of relatively small, older randomized trials, in which intakes of polyunsaturated fat were increased (even up to 20% of calories), rates of CHD were generally reduced. In a more recent detailed examination of fatty acid intake within the Nurses' Health Study, greater intake of linoleic acid, up to about 8% of energy, has been strongly related to lower incidence of myocardial infarction or CHD death. Because n-3 fatty acids were also related inversely to risk of CHD, the ratio was unrelated to risk. n-6 Fatty acids reduce insulin resistance, probably by acting as a ligand for peroxisome proliferator-activated receptors-gamma, and intakes have been inversely related to risk of type 2 diabetes. Adequate intakes of both n-6 and n-3 fatty acids are essential for good health and low rates of cardiovascular disease and type 2 diabetes, but the ratio of these fatty acids is not useful. Reductions of linoleic acid to "improve" this ratio would likely increase rates of cardiovascular disease and diabetes.

• Authors: Walter C Willett
• Journal: Journal of cardiovascular medicine (Hagerstown, Md.) (J Cardiovasc Med (Hagerstown)) Vol. 8 Suppl 1 Pg. S42-5 (Sep 2007) ISSN: 1558-2027 [Print] United States
• PMID: 17876199 (Publication Type: Journal Article, Review)

Chemical References

• Fatty Acids, Omega-6
• Lipids
• NF-kappa B
• Receptors, Tumor Necrosis Factor
• Linoleic Acid

Topics

• Cardiovascular Diseases (blood, prevention & control)
• Diabetes Mellitus, Type 2 (prevention & control)
• Fatty Acids, Omega-6 (pharmacology, therapeutic use)
• Humans
• Inflammation (metabolism)
• Insulin Resistance
• Linoleic Acid (pharmacology)
• Lipids (blood)
• NF-kappa B (drug effects, metabolism)
• Receptors, Tumor Necrosis Factor (drug effects, metabolism)