Get your vitamin D

Zoomer | June 6th, 2008

The sunshine vitamin is hot.

While Vitamin D has been long known to help prevent osteoporosis and tuberculosis, recent research has produced a seemingly endless list of other health benefits including reduced risk of cancer, diabetes, multiple sclerosis, depression and heart disease.

To review just a few recent findings:

– People who took calcium and Vitamin D and had higher levels in their blood were 77 per cent less likely to develop cancer after the first year, compared to those who took placebos or only calcium, according to a study conducted at Creighton University in Nebraska. (Read more.)

– Canadian researchers found that Vitamin D can play a role in breast cancer recovery. The findings, released by the American Society of Clinical Oncology,suggested that women who are deficient in Vitamin D at the time of a breast cancer diagnosis are more likely to see the disease spread (94 per cent) or die from it (73 per cent).

– People with a Vitamin D deficiency could face up to twice the risk of a heart attack or stroke than those with higher levels of the vitamin. This is according to a Harvard Medical School study. (Read Vitamin D deficiency linked to increased heart risk.)

– Vitamin D may be linked to juvenile diabetes, according to a paper published in Diabetologia. Researchers found that the rate of diabetes tends to be low or even non-existent near the equator — and then rises steadily at progressively higher latitudes where for much of the year sunshine is too weak to allow children to produce Vitamin D through exposure to sunlight. (Read the full media report.)

– Low levels of Vitamin D may also increase the risk of depression in older adults, Dutch researchers found.

– And according to a US study, people who took Vitamin D supplements had a 7 per cent reduction in mortality from all causes. (Source: The Washington Post.)

Too little of a good thing?

In light of these dramatic findings and the many possible health benefits of vitamin D, nutrition experts say we are getting far too little of it.

In fact, 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.

The D-bate

To help clarify matters, Health Canada says it will launch a study by this fall to investigate claims linking Vitamin D deficiency with chronic diseases, according to media reports.

The pressure on Health Canada to conduct such an investigation has been rising because of the major disagreements among respected public-health agencies about recommended daily dosage, the Globe and Mail reported. Some experts say the current Health Canada levels, which were developed in 1997, are seriously outdated and based mainly on the levels of Vitamin D needed to prevent childhood rickets.

“Despite 20 years of mounting evidence that the general public is Vitamin D deficient (over one billion world-wide) and the great impact that elimination Vitamin D deficiency would have on Canadians, Health Canada still does not have a policy in place that addresses this problem,” Maurice Shpur, Managing Director of the Vitamin D Society told CARP, Canada’s Association for the Fifty-Plus.

To oversee the framework, education and implementation of policy, the House of Commons Standing Committee on Health should institute a Royal Commission, Mr. Shpur says.

The commission would also “clarify the many, many contradictory facts and conflicting advice the public receives,” he adds.

It is a position that CARP supports. “Promoting better health and well-being of Canadians is a priority for CARP,” says Susan Eng, CARP’s Vice President of Advocacy. “We recommend that Health Canada revise their dosage recommendations for Vitamin D to reflect recent research on its many health benefits, and that they increase their efforts to promote the daily intake of Vitamin D since a large portion of the population is Vitamin D deficient.”

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.

Leading international Vitamin D researchers have advised that both the US and Canadian governments should revise their recommendations to range from 1,000 to 2,000 IU a day. And even this may be modest: a report by the Vitamin D Society says that some scientists put the safe upper limit at 10,000 IU per day, with daily needs ranging between 3,500 and 6,000 IU.

The bottom line: While advice about dosage is widely conflicting, at present many experts continue to recommend not taking more than 2,000 IU daily to avoid side affects such as nausea, constipation, abnormal heart rhythm, and kidney stones. Others put the upper limit at 1,000 units per day.

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

What about sunshine?

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.

Two factors may hinder our ability to derive Vitamin D from sunlight, which is its natural source. For those living in northern climes, winter sunlight exposure is often insufficient to produce significant amounts of it. And during the warmer months, use of sunscreen can prevent our bodies from replenishing its stores. If you use a sun protection factor (SPF) of 8 or greater, you block your body’s ability to synthesize sunlight into Vitamin D, according to the
US National Institutes of Health (NIH).

In fact, in contrast to years of advice to apply sunscreen before going outdoors, short periods of unprotected sun exposure can be beneficial to your health, experts now say. The key is moderation. 10-15 minutes of exposure to the face,
hands or back is usually enough to provide sufficient vitamin D, according to the NIH.

This is by no means an invitation to return to the free-wheeling days of ‘shake and bake’. The initial 10-15 exposure to sunlight should be immediately followed by application of sunscreen with an SPF of at least 15 to avoid risk for skin cancer, experts say.

Fast facts about 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 and beverages such as milk, margarine and soy milk.

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: 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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