According to a study conducted at University Hospital, in Uppsala, Sweden and reported in the most recent New England Journal of Medicine, middle-aged men with higher levels of viamin A in their blood, had a higher risk of bone fracture as they aged.
This study raises concerns about RDI (Recommended Daily Intake) levels of vitamin A, with many suggesting that the present RDI level may be too high. It also calls into question the benefits of vitamin A supplementation. No data was collected about dietary vitamin A consumption or behavior and activity over the intervening 30 years that might also have been involved in the higher fracture rate.
The sutdy was conducted on over 2300 subjects, based on blood taken up to 30 years ago (then aged 49-51)
The same study also examined blood levels of beta-carotene and found no correlation between higher blood levels and increased fracture risk.
Reference: New England Journal Of Medicine (vol 348, p 287)