Vitamin D
Vitamin D has, over the last few years, gone from an also-ran to a front runner in the vitamin league tables. Vital for allowing our bodies to absorb the calcium we need to make strong bones and teeth, vitamin D is also a health-booster in other ways. It helps keep our immune system in good shape, can reduce the risk of some types of cancer and may also cut our risk of long-term conditions such as multiple sclerosis.
Now new research carried out at the Heart Institute of the Intermountain Medical Center in Utah suggests that this Hercules of a vitamin may contribute to our heart health as well. In fact, not having enough vitamin D may increase our risk of heart disease and stroke.
The research, which was presented at the American Heart Association Scientific Conference in Florida, was carried out with over 27,600 people aged 50 or over. None of the participants had any history of cardiovascular disease.
First the participants were divided into three groups, according to their vitamin D levels. The normal group had over 30 nanograms of the vitamin per millilitre, the low group had 15-30 ng/ml and the very low had less than 15 ng/ml. Researchers then followed the patients for over a year, to see if any of them developed heart disease.
The study found that those participants with very low levels of vitamin D were 77% more likely to die, 45% more likely to develop coronary artery disease and 78% more likely to have a stroke than patients with normal levels of vitamin D.
Vitamin D has been linked to the regulation of blood pressure, inflammation and glucose control. All of these factors play their part in heart health. However, this study may have taken us one step further.
"This was a unique study because the association between vitamin D deficiency and cardiovascular disease has not been well-established," says Brent Muhlestein MD, director of cardiovascular research at the Heart Institute at Intermountain Medical Center and one of the authors of the study. "Its conclusions about how we can prevent disease and provide treatment may ultimately help us save more lives."
The results, when they came back, were quite surprising, and very important, says Heidi May, PhD, MS, an epidemiologist with the Center, and another study author.
"We concluded that among patients 50 years of age or older, even a moderate deficiency of vitamin D levels was associated with developing coronary artery disease, heart failure, stroke and death," she says. "This is important because vitamin D deficiency is easily treated. If increasing levels of vitamin D can decrease some risk associated with these cardiovascular diseases, it could have a significant health impact."
The study was observational, and so doesn’t give definite evidence of a link between a deficiency of vitamin D and heart disease. Clearly more work needs to be carried out. Dr Muhlestein believes the results of this study will spark further research. "We believe the findings are important enough to justify randomised treatment trials of supplementation in patients with vitamin D deficiency to determine for sure whether it can reduce the risk of heart disease," he says.
So how you get your vitamin D? The best source is from the sun. Our bodies make vitamin D when sunlight touches our bare skin. The National Osteoporosis Society says that in the UK we should have 10 minutes' exposure to sunlight twice every day from May to September (depending on skin type). This should be without sunscreen, but taking care not to get sunburnt.
We can also get vitamin D from food. Oily fish contains a reasonable amount, cod liver oil contains a lot (proving our mothers or grandmothers were right), and it occurs in smaller amounts in eggs, meat and fortified breakfast cereals and margarine.
If you are concerned that your intake of vitamin D is still too low, you can take vitamin D supplements, although you may find it difficult to find vitamin D on its own. You can take cod liver oil, which counts as a vitamin D supplement, or choose a multi-vitamin which includes it.
"It is important that people who find it hard to get enough vitamin D from the sun and their diet take a vitamin D supplement," says Sian Porter of the British Dietetic Association. The Department of Health recommend a daily supplement of 10 micrograms per day for people aged 65 and over, and for people who spend a lot of time indoors, or who cover their skin for cultural reasons and so get little exposure to the sun.
Don’t overdo the vitamin D though. Too much exposure to the sun, as well as bringing a risk of skin cancer, doesn’t increase your vitamin D levels. And high doses of vitamin D supplements can be toxic. If in doubt, check with your GP or pharmacist.
First published March 19, 2010
Useful website
British Dietetic Association - www.bda.uk.com