Some vegetables (commonly consumed by humans) efficiently modulate bone metabolism

We have hypothesized that some vegetables which are part of the regular human diet may contain modulators of bone metabolism. To mimic a typical Western diet with large proportions of refined components, rats were pair-fed a semi-purified diet to which, in the treated animals, the dried material under investigation was added. Effects are expressed as % of untreated control. Bone parameters in rats were assessed in the proximal tibia by pQCT. Bone resorption (BR) was assessed by the urinary excretion of [3H]-tetracycline from prelabeled rats. Daily administration of 1 g of onion during 4 weeks increased total bone mineral content by 17.4% (p<0.05), trabecular bone mineral density by 13.6% (p<0.05). One g of onion/day administered to male rats blunted BR by 23-/+5% (p<0.05). Daily administration of onion to ovariectomized rats inhibited BR in a dose-dependent manner. At the highest dose (1.5 g of onion) BR was inhibited by 26-/+4% (p<0.01) as compared to 24-/+3% (p<0.001) for estradiol (27microg/kg/day). An additional 13 vegetables displayed significant effects on BR at the dose of 1g/day. Interestingly, 1g/day of soy did not inhibit BR in this model. Also, skimmed milk, meat and egg (all 1 g/day) were ineffective. Thus, common vegetables consumed by humans potently modulate bone metabolism in the rat. This opens the possibility to develop the basis for a low-cost, safe and effective nutritional approach to osteoporosis.