While both omega-3 and omega-6 fats are essential for health, the typical U.S. diet contains an abundance of omega-6 fatty acids, whereas consumers have to make a point of consuming food sources of omega-3s. A low dietary omega-6 to omega-3 fatty acid ratio is associated with reduced breast cancer risk. In fact, the level of omega-6 compared to omega-3 fats in the diet has been found to be related to breast cancer risk whereas the absolute level of omega-6 fats has not. It has been suggested that an omega-6 to omega-3 ratio of two-to-one or lower is ideal, although no studies have specifically examined the influence of such a low ratio on breast cancer risk.

One reason that a high omega-6 to omega-3 ratio is associated with increased breast cancer risk is that it appears to increase breast density, a powerful breast cancer risk factor. Women with mammographically dense breasts have at least four times the risk of breast cancer compared to those with less dense breasts. Several studies have reported that low dietary omega-6 to omega-3 ratios reduce breast density in animal models of breast cancer. Now a new study has reported that women who consume a diet high in omega-6 compared to omega-3 fats have higher breast density.

Latest research finds omega-3 and omega-6 fats linked to breast density

The study referenced at the beginning of this news story was designed to investigate the association between dietary intake of omega-3 and omega-6 fatty acids and mammographic breast density. The study included 1,580 women, of whom 777 were premenopausal and 783 were postmenopausal. A self-administered food-frequency questionnaire was used to measure fatty acid consumption and the women were assigned to groups (quartiles) depending on their levels of omega-3, omega-6 and omega-6/omega-3 intake. A computer-assisted method was used to determine breast density. Statistical analyses were performed to evaluate the associations of quartiles of fatty acid intake with breast density.

Breast density was found to decrease with increasing levels of omega-3 fatty acid consumption: for increasing quartiles of omega-3 intake, the average breast density was 29%, 29%, 27%, and 25%, respectively. However, this association was statistically significant only among postmenopausal women.

No significant link was found between omega-6 fatty acid intake and breast density. However, breast density was found to be associated with the dietary omega-6/omega-3 ratio: for increasing quartiles of omega-6/omega-3 intake, the average breast density was 26%, 27%, 29%, and 29%, respectively. The authors conclude that higher intake of omega-3 fats was associated with lower breast density in the study population, suggesting that increased omega-3 intake could be a strategy for breast cancer prevention.

Please see our articles on breast density and recommended fatty fish for more information.