Protective effects of fish intake and interactive effects of long-chain polyunsaturated fatty acid intakes on hip bone mineral density in older adults: the Framingham Osteoporosis Study

Background: Polyunsaturated fatty acids and fish may influence bone health. Objective: We aimed to examine associations between dietary polyunsaturated fatty acid and fish intakes and hip bone mineral density (BMD) at baseline (1988-1989; n = 854) and changes 4 y later in adults (n = 623) with a mean age of 75 y in the Framingham Osteoporosis Study. Design: BMD measures were regressed on energy-adjusted quartiles of fatty acid intakes [n-3 (omega-3): alpha-linolenic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and EPA+ DHA; n-6 (omega-6): linoleic acid (LA) and arachidonic acid (AA); and n-6: n-3 ratio] and on categorized fish intakes, with adjustment for covariates. Effect modification by EPA+DHA intake was tested for n-6 exposures. Results: High intakes (>= 3 servings/wk) of fish relative to lower intakes were associated with maintenance of femoral neck BMD (FN-BMD) in men (dark fish + tuna, dark fish, and tuna) and in women (dark fish) (P < 0.05). Significant interactions between AA and EPA+DHA intakes were observed cross-sectionally in women and longitudinally in men. In women with EPA+DHA intakes at or above the median, those with the highest AA intakes had a higher mean baseline FN-BMD than did those with the lowest intakes (quartile 4 compared with quartile 1: P = 0.03, P for trend = 0.02). In men with the lowest EPA+DHA intakes (quartile 1), those with the highest intakes of AA (quartile 4) lost more FN-BMD than did men with the lowest intakes of AA (quartile 1; P = 0.04). LA intake tended to be associated with FN-BMD loss in women (P for trend < 0.06). Conclusions: Fish consumption may protect against bone loss. The protective effects of a high AA intake may be dependent on the amount of EPA+DHA intake. Am J Clin Nutr 2011;93:1142-51.