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STUDY: Vit A and Weak Bones
JOURNAL: N Engl J Med 2003;348:287-294,347-349.
AUTHORS: Dr. Karl Michaelsson
ABSTRACT: High serum retinol levels are associated with an increased risk of fracture in men.
COMMENTARY: The findings suggest that vitamin A levels in fortified foods and vitamin supplements may need to be reassessed since they are a major contributor to serum retinol levels, the study authors note.
Dr. Karl Michaelsson of University Hospital in Uppsala, Sweden and colleagues, studied 2322 men, between 49 and 51 years of age, who were followed for 30 years.
The researchers found that men with the highest serum retinol levels were 1.64 and 2.47 times more likely to sustain any fracture and a hip fracture, respectively, than their peers with lower levels.
In contrast, levels of beta-carotene, a precursor to vitamin A, were not associated with fracture risk.
These findings are in agreement with those from animal and epidemiologic studies, which first suggested that that vitamin A may inhibit new bone formation and increase the risk of fractures.
In the study, men with the highest fracture risk had more than 75.62 micrograms/dL of retinol in their blood samples at the start of the study. During the study period, 266 men sustained fractures.
In an accompanying editorial, Dr. Paul Lips, from Vrije Universiteit Medical Center in Amsterdam, the Netherlands, comments that "vitamin A supplementation and fortification of food with vitamin A may be harmful in Western countries, where the life expectancy is high and the prevalence for osteoporosis is increasing."
I always use beta carotene with my patients as this is the safe alternative to Vit A. The study showed not correlation between beta carotene and fracture.
Just don't use high doses of pure vitamin A.