Vitamin D's cancer fighting potential

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Vitamin D: The Cancer Fighter

 

Health expert Patrick Holford analyses the evidence which shows Vitamin D's cancer fighting potential.

 

 

 

 

Two studies, presented in April 2006, at a meeting of the American Association for Cancer Research confirm vitamin D’s cancer protective role. In the first, high levels of vitamin D translated to a 50 percent lower risk of breast cancer. Even modestly higher levels resulted in 10 percent less risk, which would translate to 5,000 fewer cases a year if it were true for all British women.

The second study found that women who spent time outdoors or got a lot of vitamin D from their diets or supplements, or spent a lot of time outdoors especially as teenagers, were a third less likely to develop breast cancer than women with less of the nutrient. “Exposure to vitamin D at the time breasts are developing, particularly around adolescence, might be important,” said lead researcher Julia Knight of Mount Sinai Hospital in Toronto

These results support the recent review of evidence by Dr Cedric Garland and colleagues from the University of California who analysed the results of 63 studies on vitamin D and its association with cancers of the colon, breast, prostate and ovary. Twenty out of 30 studies published in the American Journal of Public Health alone found a statistically significant benefit of vitamin D for reducing risk of colon cancer or pre-cancerous colon polyps, breast cancer, prostate cancer risk and ovarian cancer.

What these studies show is that an intake of 25mcg – that’s five times the RDA – confers the best protection against these cancers. These cancers account for the majority of cancer deaths. Yet studies indicate that vitamin D could cut risk by up to 50%. That means that the simple action of upping vitamin D intake could literally save hundreds of thousands of lives at a cost of little more than 5p a day.

Vitamin D’s anti-cancer power is due to its ability to block the growth of new blood vessels that allow tumours to grow, a process known as angiogenesis. It also helps healthy cells stick together by “enhancing intercellular communication through gap junctions, thereby strengthening the inhibition of cancer cell growth that results from tight physical contact with adjacent cells within a tissue," according to Garland.

The RDA for vitamin D, which is based largely on what you need for healthy bones, it is woefully inadequate for cancer prevention. In fact, the chances are that even if you’re taking supplements with higher-than-RDA-levels, you’re probably still not getting nearly enough. There is also the assumption that you can make enough vitamin D if you have enough sun exposure. What this study shows is that vitamin D deficiency exists even in sunny Southern California – and may be made worse by too much sunscreen, hats and protective clothing.

So what does this mean to you in terms of diet and supplements? The average dietary intake is 4mcg, but this is based largely on a fish-free diet since most people eat very little. So what should you do?

Eat FishThe best dietary way to up your Vitamin D in take is to eat fish. A 100g (3.5oz) serving of salmon or mackerel provides around 9mcg, and a 100g can of sardines provides 7.5mcg. I always recommend eating oily fish such as these three times a week.

Eat EggsAn egg provides about 1mcg – slightly more if it’s an omega-3-rich egg such as Columbus or Intelligent Eating eggs, and slightly less if it isn’t. I always recommend eating six eggs a week. Milk is also a good source of vitamin D (a glass of milk provides 2.5mcg) but I don’t recommend it because increased milk consumption is associated with increased risk of these cancers.

If you follow my recommendations you’ll probably achieve close to 6.4mcg a day.

Miriam Nelson, professor of nutrition at Tufts University and author of Strong Women, Strong Bones, recommends exposing your skin (arms and legs, not face) without sunscreen to the sun for about 10 to 15 minutes a day, which provides the equivalent to about 5mcg of vitamin D.

So food plus sun can provide around 11.4mcg a day. With the ideal intake being 25mcg, that leaves a shortfall of 13.6mcg a day. The better, high-potency multivitamins provide 5mcg. So the chances are that if you’re taking a multi, have a good diet and spend time outside, your total intake is around 17.5mcg. That leaves a shortfall of around 7.5mcg – or 12.5mcg if you don’t get the sun exposure. This amount is worth supplementing.

If you are taking a bone-friendly formula, this might well provide the extra 7.5mcg. Otherwise it’s worth adding a vitamin D supplement. You can buy supplements of vitamin D in health food stores that provide 25mcg. Since vitamin D is stored in the body (rather than being excreted daily, like water-soluble vitamins), taking two 25mcg tablets a week would make up the shortfall. There are no safety concerns with vitamin D – even at levels ten times higher than this.

I’m sure this research will have the effect of increasing the amounts put in supplements from the current 5mcg to 12.5mcg and certainly doubly emphasizes the need to eat fish.

By Patrick Holfordhttp://50connect.co.uk/index.asp?main=http%3A//50connect.co.uk/50c/articlepages/health_index.asp%3Fsc%3Dhealthyeating%26aID%3D14305