Excess Vitamin D doubles heart condition risk

Vitamin D, also known as the 'sunshine' hormone, promotes calcium absorption, helping maintain bone strength. Although there is no lack of sunshine in Australia, many people are Vitamin D deficient, leaving them at risk of muscle and bone weakness.

"Studies show a significant number of Australians have at least marginal vitamin D deficiency, with two studies showing rates of 43 percent in young women and 23 percent in the general adult population," says Dr Michael Holick, author of The Vitamin D Solution (Scribe, $35).

This increased awareness of vitamin D deficiency has led many to seek out supplements to ensure they get enough, but according to a recent survey, too much may increase the risk of developing a serious heart condition.

Researchers at the Intermountain Medical Centre in Utah looked at blood tests from 132,000 patients and found those with excess levels of the vitamin in their blood were 2.5 times more likely to have atrial fibrillation (AF), a type of heart flutter which can lead to stroke.

They found those with vitamin D levels above 100 nanograms per 100ml, were 2.5 times more likely to have AF as those with normal levels (41-80ng/100ml).

Heart rhythm specialist Dr T Jared Bunch advised patients to tell their doctors what vitamin supplements they were taking.

"Patients don't think of vitamins and supplements as drugs. But any vitamin or supplement that is touted as 'healing' or 'natural' is a drug and will have effects that are both beneficial and harmful," he said.

"Just like any therapy, vitamins need to be taken for the right reasons and at the right doses."

Vitamin D is produced naturally with exposure to the sun — 15 minutes a day should be enough to obtain adequate amounts. Dietary sources include eggs, salmon, sardines, herrings, mackerel, swordfish and other oily fish. Discuss with your doctor if you think you require supplementation.