Background: Several lines of evidence suggest that n–3 fatty acids reduce the risk of some chronic diseases, including heart disease, diabetes, and cancer. Other research, mainly in animals, also suggests a role in bone health.

Objective: We aimed to investigate the association between the ratio of dietary n–6 to n–3 fatty acids and bone mineral density (BMD) in 1532 community-dwelling men and women aged 45–90 y.

Design: Between 1988 and 1992, dietary data were obtained through self-administered food-frequency questionnaires, and BMD was measured at the hip and spine with the use of dual-energy X-ray absorptiometry. A medical history was obtained and current medication use was validated. Age- and multiple-adjusted linear regression analyses were performed.

Results: There was a significant inverse association between the ratio of dietary linoleic acid to -linolenic acid and BMD at the hip in 642 men, 564 women not using hormone therapy, and 326 women using hormone therapy; these results were independent of age, body mass index, and lifestyle factors. An increasing ratio of total dietary n–6 to n–3 fatty acids was also significantly and independently associated with lower BMD at the hip in all women and at the spine in women not using hormone therapy.

Conclusions: A higher ratio of n–6 to n–3 fatty acids is associated with lower BMD at the hip in both sexes. These findings suggest that the relative amounts of dietary polyunsaturated fatty acids may play a vital role in preserving skeletal integrity in older age.

PMID 15817874