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11:35AM Sunday 05 July, 2009

Step out of the shadows

4 December 2008

| Karen McElroy

There has been lots of attention given to vitamin D lately – with major research pointing to vitamin D deficiency and its role in a host of disorders including cancer, infertility, MS and even obesity.

For many years we have been aware of how over-exposure to the sun contributes to skin cancers – with the resultant campaign to “slip, slop, slap”.

In light of the new research, there is now much questioning about whether the “sun smart” message has gone too far, with many people fanatically avoiding exposure to the sun and also overusing sunscreen.

This leads to the body having little opportunity to make vitamin D and thus deficiencies are now widespread. It is no longer acceptable to assume that because we live in a sunny climate that we automatically get enough sun to ensure adequate vitamin D levels.

It is now estimated many people have some form of vitamin D deficiency. We now spend far less time outdoors, with many people being indoors much of the day or avoiding the sun for fear of skin cancer.

Vitamin D is formed in the skin on exposure to sunlight or it can also be eaten in the diet.

Being a fat soluble vitamin, it is only present in the fatty portion of foods. So people on low fat diets will directly limit their intake of both vitamin D and other fat soluble vitamins. This also applies to people with digestive disorders or those on drugs that inhibit fat absorption.

Good sources of vitamin D rich foods are liver, fatty fish, eggs and butter. Remember that eggs need to be free range, as chickens require sunlight on their feathers to make vitamin D.

Other people at higher risk of deficiency are people with dark skin, who need much more sun exposure to make adequate amounts, the elderly and fair-skinned people who avoid the sun. Babies and children can be at risk and new USA guidelines now recommend that vitamin D supplements be given to all infants because it is so important.

Vitamin D has perhaps been misnamed historically as a vitamin, as we now know that it works much more like a hormone. Some people will be aware of the role that vitamin D has in ensuring strong bones and how it can be used to treat rickets (weakened bones).

However, vitamin D actually forms a potent hormone-like agent that is involved in growth, repair and maintenance of many tissues and targets more than 200 genes. The beneficial effects that vitamin D can provide are far-reaching.

In one research paper, there was a dramatic reduction in cancer rates when people took a vitamin D supplement.

Thus, while we are told by some experts to use sunscreens to prevent skin cancer, many others are now arguing slapping on sunscreen actually contributes to far more cancer deaths than it prevents, due to the lack of this vital vitamin production. More than 16 different cancers have been linked to vitamin D deficiency.

One Harvard researcher found that vitamin D may prevent as many as 30 deaths for each death caused by skin cancer. The American Cancer Society has now started reconsidering its own sun guidelines.

New evidence has also found many sunscreens contain harmful chemicals that are potentially cancer causing and it is worth sourcing natural zinc based sunscreens.

The mechanisms by which vitamin D reduces your risk of cancer are fairly well understood. They include enhancing calcium absorption, reducing metastasis or cancer spreading, inducing cell differentiation and increasing cancer cell death.

But it is not just cancer that appears to be linked to vitamin D’s status. One study has found men with sperm abnormalities had a high incidence of vitamin D deficiency.

While scientists at UQ have linked vitamin D deficiency in pregnancy to abnormal foetal brain development and an increase of the risk of behavioural problems, schizophrenia and multiple sclerosis later in life.

A study just released showed that young women with insufficient vitamin D levels had significantly higher weight and fat stores compared with women with normal levels of vitamin D. Interestingly, the study also found that about 60% of the women were deficient in vitamin D – despite living in sunny California.

The advice we are now getting is we need adequate sun exposure to make optimal levels of vitamin D for long-term health.

The intensity of the sun varies with the seasons, so our need for sunshine must vary also.

Most people will need 10-15 minutes of sun exposure in the middle of the day on face and upper limbs 4-6 times a week in summer and 30 minutes in winter. We still need to be very sensible in the sun and avoiding getting sun burnt. Sun burn is very damaging and is linked to skin cancer. Sunscreen, hats and covering up is still prudent when sun exposure will extend beyond 15-20 minutes at a time or the UV index is moderate or high.

But perhaps spending a bit more time outdoors (without sunscreen) a few times a week, may offer much more for our health than a rosy glow.

– Karen McElroy, naturopath and herbalist, Mary Street Wellness, Ph: 5449 7958, www.karenmcelroy.com.au

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