Vitamin D deficiency can be deadly

The health benefits of vitamin D are numerous, including a reduced risk of cancer, diabetes, and osteoporosis.

Yet according to experts, vitamin D deficiency is widespread — and as a result, many may be putting themselves at increased risk for chronic disease. In fact, according to the Vitamin D Society, elimination of vitamin D deficiency in Canada could prevent 140,000 cases of serious chronic diseases and 24,000 unnecessary deaths each year.

And now there’s yet more evidence that vitamin D deficiency can be deadly.

A German study has found that vitamin D deficiency is associated with heart dysfunction, sudden cardiac death, and death due to heart failure, Reuters reported.

Researchers from the University of Heidelberg reviewed vitamin D levels in 3,299 Caucasian patients who were tested for clogged heart arteries (coronary angiography) from 1997 to 2000. The subjects were then followed for nearly eight years.

During this time, 116 patients died from heart failure and 188 from sudden cardiac death. When assessing the results, researchers found that people with severe vitamin D deficiency were nearly three times more at risk of death from heart failure and about five times more at risk of sudden cardiac death.

“These data strongly indicate that the maintenance of an optimal vitamin D status may be a promising approach for the prevention and/or therapy of (heart) diseases, warranting confirmation in interventional trials with vitamin D supplementation,” the researchers conclude. (Read the study abstract at Journal of Clinical Endocrinology and Metabolism.)

How much is enough?

Anywhere from one-third to one-half of otherwise healthy middle-aged and older adults in developed countries are deficient in vitamin D, according to the Mayo Clinic. The deficiency is mostly attributed to lack of sun exposure, pigmented skin that prevents penetration of the sun’s rays and an inadequate intake of vitamin D enriched foods.

But how to make sure you’re getting the right dose of vitamin D? There appears to be no easy answer. If you ask Health Canada, for example, an adequate daily intake for people aged one to 50 is 200 International Units (IU). For ages 51-70, the recommended dose is 400 IU, and for people over 70, 600 IU.

However, in response to studies linking Vitamin D with cancer prevention, the Canadian Cancer Society now recommends that adults with white skin take 1,000 units each day in fall and winter. People with dark skin are advised to take this amount throughout the year.

And the Canadian Pediatric Society recently updated its recommendation for pregnant women, saying they should take 2,000 IU daily.

How much is too much?

To avoid health risks associated with taking too much vitamin D, Health Canada recommends no more than the Tolerable Upper Intake Level set for adults at 2000 IU/day from all sources of vitamin D, including milk and over the counter supplements. Side effects of too much vitamin D can include nausea, constipation, abnormal heart rhythm, and kidney stones.

Note: It’s nearly impossible to get too much Vitamin D from sunlight or foods. Nearly all Vitamin D ‘overdoses’ come from supplements.

Vitamin D: Fast facts

– Vitamin D is known as the “sunshine vitamin” for good reason. Exposure to sunlight triggers the synthesis of vitamin D in the body. In fact, natural sun can produce 20,000 IU of vitamin D in only about 20 minutes of sun exposure when the sun is ‘high in the sky’. While the body can only use a portion of this, it can be stored for times when we don’t make vitamin D.

– The only natural foods containing vitamin D are egg yolk, liver and fatty fish, such as salmon, tuna, mackerel and sardines. It is also found in fortified foods such as some cereals, margarine and beverages (milk and soymilk).

– Vitamin D is available over the counter in 1,000 IU pills or drops.

– Are you vitamin D-deficient? A simple blood test — the 25(OH) D or calcidiol test — can indicate if your vitamin D level is low.

Sources : Reuters; Journal of Clinical Endocrinology and Metabolism, October 2008; American Society of Clinical Oncology; Health Canada; Multiple Sclerosis Resource Centre; Vitamin D Society; US National Institutes of Health; Mayo Clinic.

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