n-6 Polyunsaturated Fatty Acids and Cancer

1. It is important to consume a balanced diet containing about 25–35% energy from fat. In order to reduce the risk of disease related to high fat intake, a restricted total calorie intake would be beneficial, while consuming approximately 30% total calories from fat. 2. A high fat intake is generally associated with cardiovascular diseases, cancer, and other chronic diseases. However, a diet low in fat and high in carbohydrates may also be associated with the diseases because it may reduce HDL cholesterol and increase serum triacylglycerol concentrations. 3. The recommended ratio of n-6 polyunsaturated (PUFA) fats to n-3 polyunsaturated fat is 1–2:1. Populations that consume low levels of n-6 PUFA and high levels of n-3 PUFA appear to have reduced incidence of heart disease, diabetes, arthritis, and cancer. 4. High n-6 PUFA intake is associated with cancer because it promotes preexisting tumor growth and accelerates cancer metastasis. The eicosanoids in n-6 PUFA have also been found to increase cell proliferation and be inflammatory. 5. A high intake of n-6 PUFA has been directly related to breast cancer; however, this is seen in animal studies, whereas no effect has been found in human studies. It is certain that dietary fat intake may directly affect breast cancer risk, but the effect may depend on the type of fat and age when the fats were consumed.