Excessive Vitamin D May Be Harmful

Vitamin D may increase mortality when too much is consumed

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Vitamin D is known to strengthen bones and can be particularly beneficial in protecting the elderly from brittle bones. However, it is possible to consume an excessive, potentially harmful, amount of vitamin D.

A recent study has found a correlation between higher mortality and high quantities of vitamin D, suggesting the vitamin doesn't always offer a protective quality.

"Consume plenty of vitamin D, but don't overdo it."

Darshana Durup, a doctoral student at the University of Copenhagen in Denmark, said that in the recent study researchers found higher mortality in individuals with low vitamin D levels, but were surprised by similar findings in those who consumed large amounts of vitamin D.

The research is not the first to suggest that too much vitamin D could be harmful. A Johns Hopkins University study published in the American Journal of Cardiology in January found an association between high levels of vitamin D, and cardiovascular inflammation and plaque build up in the arteries.

During the large study investigators studied blood samples from 247,574 residents of Copenhagen through the country's civil registration system.

They analyzed the blood, determining that if the blood contained less than 10 nanomol of vitamin D per liter, mortality was more than twice as high. In comparison individuals with high amounts of vitamin D, or more than 140 nanomol in their blood, had a risk of dying that was 1.4 times higher as compared to those with average levels, or about 50 nanomol, where risk is lowest.

Additional research is needed to confirm the finding. Scientists have not yet identified the cause of the higher mortality risk.

"It is important to conduct further studies in order to understand the relationship. A lot of research has been conducted on the risk of vitamin D deficiency. However, there is no scientific evidence for a ‘more is better’ argument for vitamin D, and our study does not support the argument either. We hope that our study will inspire others to study the cause of higher mortality with a high level of vitamin D," Durup said.

The study was recently published in the Journal of Clinical Endocrinology and Metabolism.

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Review Date: 
May 29, 2012
Last Updated:
May 29, 2012