The effect of siderosis and ascorbic acid depletion on bone metabolism, with special reference to osteoporosis in the Bantu.

I. There is an association between iron overload, ascorbic acid deficiency and osteoporosis in middle-aged South African Bantu males. The iron overload contributes to the ascorbic acid deficiency by accelerating its oxidative catabolism. The object of the present investigation was to explore the possibility that the osteoporosis results from chronic ascorbic acid deficiency. 2. On quantitative microradiography, percentage bone-formation surface was normal but percentage bone-resorption surface was significantly increased in ten osteoporotic subjects compared with seven control subjects. 3. There was a significant inverse correlation between bone mineral density and liver storage iron concentration in thirty-five Bantu subjects. In thirteen individuals aged 39 years or less, liver storage iron concentration was significantly correlated with percentage bone-resorption surface. 4. Guinea-pigs deprived of ascorbic acid for 7.1 d exhibited both significantly diminished percentage bone-formation surface and increased percentage bone-resorption surface. 5. Guinea-pigs overloaded with iron by injections of iron dextran developed significantly reduced hepatic ascorbic acid concentrations and bone mineral densities; percentage boneformation surface was significantly diminished and percentage bone-resorption surface significantly increased. Ascorbic acid injection largely prevented the bone changes.