Can we overdose on too much Vitamin D?

Posted in Avonmore, Nutrition, Super Milk, Vitamin D by admin on December 1st, 2009

One of the debates surrounding vitamin D is whether too much can be toxic. The US’s Institute of Medicine’s recommendations – unchanged since 1997 – were influenced in part by a 1984 study concluding that 3,800 IU of vitamin D per day could cause hypercalcemia, or too much calcium in the blood. Symptoms include kidney stones, vomiting and muscle atrophy.

But the 1984 study was flawed: it failed to measure the amount of vitamin D administered; based on the findings of other studies, it now looks as though subjects were given 100 times more vitamin D than intended.Moreover, how could it be that 3,800 IU was toxic, when 20 minutes of midday sunbathing in the summer makes at least 10,000 IU of vitamin D in our bodies?

In 1999, Reinhold Vieth (pictured right) published a review of vitamin D research in response to the IOM conclusions. In it, he argued that there was no evidence that amounts lower than 20,000 IU a day could be toxic. “Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D,” Vieth wrote.

Studies have since shown 10,000 IU a day of vitamin D to be safe. While any substance will become toxic in excess, vitamin D researchers today accept that the current vitamin D recommendations could be more than quadrupled with no fear of toxicity.

Source: Financial Times, Sam Apple, Published: October 23 2009 16:56 | Last updated: October 23 2009 16:56