Repletion with (n-3) fatty acids reverses bone structural deficits in (n-3)-deficient rats

(n-3) PUFA deficiency and repletion effects on bone mechanical properties have not been examined. The primary research aim was to evaluate whether changes in the fatty acid composition of bone tissue compartments previously reported to influence bone formation rates would affect bone modeling and mechanical properties. In this investigation, three groups of rats were studied, second generation (n-3)-deficient, (n-3)-repleted, and a control (n-3)-adequate. The (n-3)-adequate diet contained alpha-linolenic acid LNA, 18:3(n-3), 2.6% of total fatty acids] and docosahexaenoic acid DHA, 22:6(n-3), 1.3% of total fatty acids]. Fatty acid composition of the hindlimb tissues (bone and muscle) of chronically (n-3)-deficient rats revealed a marked increase in (n-6) PUFA 20:4(n-6), 22:4(n-6), and 22:5(n-6)] and a corresponding decrease in (n-3) PUFA 18:3(n-3), 20:5(n-3), 22:5(n-3) and 22:6(n-3)]. Measurement of bone mechanical properties (energy to peak load) of tibiae showed that (n-3) deficiency diminished structural integrity. Rats repleted with (n-3) fatty acids demonstrated accelerated bone modeling (cross-sectional geometry) and an improved second moment in tibiae compared with control (n-3)-adequate rats after 28 d of dietary treatment. This study showed that repletion with dietary (n-3) fatty acids restored the ratio of (n-6)/(n-3) PUFA in bone compartments and reversed compromised bone modeling in (n-3)-deficient rats.