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High vitamin A intake may increase risk of bone fractures

High vitamin A intake may increase risk of bone fractures

According to a new study, high vitamin A intake may increase the risk of bone fractures.

Over supplementation of vitamin A in the diet is associated with decreased cortical bone thickness and increased risk of fracture, reports a study published in the Journal of Endocrinology.

The study, undertaken in mice, found that sustained intake of vitamin A, at levels equivalent to 4.5-13 times the human recommended daily allowance (RDA), caused significant weakening of the bones, and suggests that people should be cautious of consumption of excess vitamin A in their diets.

“Overconsumption of vitamin A may be an increasing problem as many more people now take vitamin supplements. An overdose of vitamin A could be increasing the risk of bone weakening disorders in humans but more studies are needed to investigate this. In the majority of cases, a balanced diet is perfectly sufficient to maintain the body’s nutritional needs for vitamin A.” said Dr. Ulf Lerner, the lead author of the study.

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Previous studies in mice have shown that short-term overdosing of vitamin A, at the equivalent of 13-142 times the recommended daily allowance in people, results in decreased bone thickness and an increased fracture risk after just 1-2 weeks. This study is the first to examine the effects of lower vitamin A doses that are more equivalent to those consumed by people taking supplements, over longer time-periods.

Dr. Ulf Lerner and colleagues reported that mice were given lower doses of vitamin A, equivalent to 4.5-13 times the RDA in humans, over a longer time period, also showed thinning of their bones after just 8 days, which progressed over the ten-week study period.

“Previous studies in rodents have shown that vitamin A decreases bone thickness but these studies were performed with very high doses of vitamin A, over a short period of time. In our study we have shown that much lower concentrations of vitamin A, a range more relevant for humans, still decreases rodent bone thickness and strength,” said Dr. Ulf Lerner.

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The researchers decided to move a step further to investigate if human-relevant doses of vitamin A affect bone growth induced by exercise, which was not addressed in this study and will also try to find out  the effects of vitamin A supplementation in older mice, where growth of the skeleton has ceased, as is seen in the elderly.

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Vinay Singh

Vinay Singh

Vinay Singh joined Medical Dialogue as Desk Editor in 2018. He covers the medical speciality news in different medical categories including Medical guidelines, updates from Medical Journals and Case Reports. He completed his graduation in Biotechnology from AAIDU and did his MBA from IILM Gurgaon. He can be contacted at . Contact no. 011-43720751
Source: With inputs from the Journal of Endocrinology

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