Polyunsaturated fatty acids can attenuate the risk of osteoporotic fracture

A new paper from Tamara Harris et al. of the National Institute of Aging (Bethesda, MD, USA) looks at PUFA and fish oil consumption and its effect on the risk of osteoporotic fractures in older adults.

To date, there have been relatively few studies relating circulating fatty acids and fracture risk. These have been inconclusive. Previously, a trial by Orchard et al (2013)2 indicated that higher Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) levels in red blood cells was protective against hip fractures. It is thought the protective effect of marine fatty acids relates to inflammatory modulation and osteoclast/osteoblast regulation at a cellular level which in turn reduces bone loss and hence helps maintain bone mineral density (BMD). Laboratory studies have shown that DHA is a potent inhibitor of the bone resorbing activities of osteoclast cells (Rahman et al3., 2008). Rat studies, meanwhile, have shown that the calcium balance increases after regular fish oil intake (Kruger and Coetzer, 1995). 

The new paper determined the number of osteoporotic fractures from an Icelandic cohort of 1438 men and women aged between 66 and 96 years at five to nine years after enrolment. Whilst fish oil intake was assessed using validated intake questionnaires, the full fatty acid profile was determined from blood phospholipid samples. The final results show a borderline lower risk of osteoporotic fracture associated with increased PUFA intake in all adults, whilst increased omega 6 fatty acid and specifically Arachidonic Acid (ARA) resulted in increased risk in women. Curiously, the benefits of fish oil consumption could not be demonstrated across the entire life span, rather a protective effect against risk of fracture was demonstrated in late life for men and midlife for women. These results could indicate that fish oil protects against osteoporosis related to the onset on the menopause in women, however once BMD has been depleted, fish oil cannot provide protection against fracture in older women.

1. Harris T.B., Song X., Reinders I., Lang T.L., Garcia M.E., Siggeirdottir K., Sigurdsson S., Gudnason V., Eiriksdottir G., Steingrimsdottir L. Aspelund T, Brouwer I.A. and Murphy R.A. Plasma phospholipid fatty acids and fish-oil consumption in relation to osteoporotic fracture risk in older adults: the Age, Gene/Environment Susceptibility Study. Am J Clin Nutr, March 2015 doi: 10.3945/ajcn.114.087502
2. Orchard T.S. et al.. The association of red blood cell n-3 and n-6 fatty acids with bone mineral density and hip fracture in the women’s health initiative. J Bone Miner Res 2013, 28:505–15.
3. Rahman M.M., Bhattacharya A. & Fernandes G. DHA is a more potent inhibitor of osteoclast differentiation in RAW 264.7 cells than EPA. J Cell Physiol 2008. 214(1): 201–209.
4. Kruger M.C. & Coetzer H.. EPA and DHA increases calcium balance. Nutritional Research 1995, 15(2): 211–219.