Researchers from Purdue University and Indiana University have found that high intake of the omega-3 fatty acid DHA inhibited bone loss in an animal model of postmenopausal osteoporosis.

Because low estrogen levels are thought to play a role in bone loss, researchers evaluated the effects of the ratio of dietary omega-6 and omega-3 fatty acids on bone mineral density in rats without ovaries.
For 12 weeks, researchers administered a high-polyunsaturated fatty acid (PUFA) diet with a ratio of omega-6s to omega-3s of 5-to-1, and a low-PUFA diet with a ratio of omega-6 to omega-3 PUFAs of 10-to-1.

Analyses confirmed that the dietary ratio of 5:1 (which had a lower amount of omega-6s in relation to the omega-3s compared to the 10:1 ratio) significantly elevated the amount of DHA in the periosteum, marrow and cortical and trabecular bones of the femur. Measurements for femur and tibia bone mineral content (BMC) and bone mineral density showed that the DHA-rich diets resulted in a significantly lower bone loss among the ovarectomized rats at 12 weeks. Regardless of the dietary PUFA content, DHA in the 5:1 diets preserved rat femur bone mineral content in the absence of estrogen.

The scientists wrote, “This study indicates that the dietary ratio of n-6/n-3 PUFAs and bone tissue concentration of total long-chain n-3 PUFAs (DHA) minimize femur bone loss as evidenced by a higher bone mineral content in ovarectomized rats.”

Reference:
Watkins BA, Li Y, Seifert MF. Dietary ratio of n-6/n-3 PUFAs and docosahexaenoic acid: actions on bone mineral and serum biomarkers in ovarectomized rats. J Nutr Biochem. 2006 Apr;17(4):282-9.