One clinical outcome that is proven to be a problem in vitamin D insufficiency/deficiency is loss of bone health. This ultimately results in an increased risk of fracture – a significant public health problem associated with high morbidity and mortality, particularly in the elderly.
A recent study (Melhus et al. J Clin Endocrinol Metab 2010 95: 2637-2645 ) in healthy elderly men demonstrated that:
1. Fracture risk increased significantly when 25(OH)D was below 16 ng/ml. This is at the low end of the consensus definition of vitamin D insufficiency. So is a vitamin D level of 20 ng/ml acceptable?
2. When 25(OH)D was very low (true vitamin D deficiency), the fracture risk was 4 times normal.
3. There was a hint (although it was only a hint) that very high 25(OH)D (overreplacement) might have a trend to increase fracture risk.