Vitamin D deficiency risk rising in northern hemisphere

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Vitamin D levels can be determined by a simple blood test. If you think you might be at risk of a vitamin D deficiency, you can ask your doctor (or another relevant member of your medical team) to do a simple blood test to determine your vitamin D level.

Now that daylengths are shortening and the temperatures are falling in the northern hemisphere, the amount of vitamin D produced naturally by the skin of northern hemispherians is likely to be falling. And if you are undergoing treatment for breast cancer or beyond treatment, you may be spending more time indoors and less time exposed to direct sunlight, which may increase the risk of vitamin D deficiency.  

Here's some background info and useful links.

It appears that most skin cancers are a consequence of the ultraviolet light in sunlight damaging our skin. There is now a lot of practical advice on skin cancer websites and in the popular literature and media on sensible ways we can protect ourselves from the kinds of sun exposure most likely to damage our skin.

Based on our current knowledge it would seem wise to adopt a lifetime policy of minimising unnecessary skin exposure to the sun, without going overboard about it. We may be particularly vulnerable in the first two decades of our lives, so parents need to take sensible measures to protect babies and children, and teach good sunsafe habits. We are advised to avoid sunburn if possible, particularly severe sunburn, and not to sunbathe or use tanning beds and similar artificial tanning aids.

On the other side of the coin, sunlight on the skin results in the production of vitamin D, which is necessary for good bone health among other things. Some evidence has also been reported that vitamin D may play a role in lowering our risk of getting several types of cancers although it is difficult to establish a connection with confidence and more research is needed.

So we need to strike a balance between protecting our skin from the ultraviolet radiation in sunlight, and getting sufficient exposure to ensure we don't become deficient in vitamin D. Fortunately for the majority of people, it doesn't take much exposure to sunlight on average per day (half an hour or less on hands, arms and face) to make sufficient vitamin D. The amount of exposure depends on various factors such as time of year, how far from the equator we live and our age.

For those who don't get sufficient sun exposure, vitamin D deficiencies can usually be overcome by taking vitamin D supplements. Pills containing vitamin D can be purchased relatively cheaply and don't require medical prescriptions. (It's possible to induce severe toxicity by taking megadoses of vitamin D way beyond the recommended doses - you can find information about this in the section called "Toxicity" in this article http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/ ).

We can also increase our vitamin D intake by eating foods rich in vitamin D. The standard cow's milk you can routinely purchase in your country may be fortified with vitamin D or there may be a fortified variety available. Some other foods could also be fortified eg some breads, breakfast cereals and margarine, but unless it says so on the label I would assume it isn't fortified. There's information about milk and other foods fortified with vitamin D in the USA in this National Institutes of Health article "Dietary Supplement Fact Sheet: Vitamin D" at http://ods.od.nih.gov/factsheets/vitamind.asp.

A good article on the amount of sun exposure we may need is on the Australian Broadcasting Commission website at www.abc.net.au/health/thepulse/s1408741.htm - it's called "Sun, bones and Vitamin D", by Peter Lavelle. Here's a quote:
"Professor Rebecca Mason, an expert on vitamin D and calcium metabolism and Professor of Physiology at the University of Sydney, says the recommended levels of sunlight exposure won't put anyone at risk of skin cancer.
Those levels are: in summer, six to eight minutes a day on most days. In winter, it should be half an hour most days. You need to have only 15 per cent of your body exposed - arms, hands and face - to get this exposure.
She agrees that most people will already get this amount. But those people in the at-risk group should make sure they get at least this amount. People with dark skin may need more.
We need to maintain a balance - we need enough sunlight to keep our bones healthy but not so much that we're at risk of skin cancer."

The recommended levels of sunlight exposure she gives need to be adjusted for your particular latitude, season and age but they give an idea of what is needed. Most pale-skinned people should be able to stay pale-skinned while ensuring their vitamin D levels are adequate. If you're worried about your vitamin D level (and I gather that most younger people who spend some time outdoors most days needn't be concerned) you can ask your doctor for a routine vitamin D test. The older you are eg over 60 the more likely you are to develop a vitamin D deficiency.

There's another good and more technical article in the Medical Journal of Australia (MJA 2005; 182 (6):281-285) on this webpage
www.mja.com.au/public/issues/182_06_210305/dia10848_fm.html. It's a position statement called "Vitamin D and adult bone health in Australia and New Zealand: a position statement" by the Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia.

Another excellent article I suggest reading is called "Vitamin D", from the Oregon State University's Linus Pauling Institute Micronutrient Information Center, at http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/ And another very good article is the USA's National Institutes of Health's "Dietary Supplement Fact Sheet: Vitamin D" I mentioned earlier, at www.ods.od.nih.gov/factsheets/vitamind.asp.

The subject of vitamin D and our health is under very active study and review by scientists at present. On the topic of any link between vitamin D levels and cancer prevention and treatment, the abovementioned USA's National Institutes of Health's "Dietary Supplement Fact Sheet: Vitamin D", published several years ago, says "Additional well-designed clinical trials need to be conducted to determine whether vitamin D deficiency increases cancer risk, or if an increased intake of vitamin D is protective against some cancers. Until such trials are conducted, it is premature to advise anyone to take vitamin D supplements for cancer prevention". The fact sheet will be updated in the northern hemisphere autumn 2008 based on a recent conference "Vitamin D and Health in the 21st Century: An Update (Sept. 5-6, 2007)", so it will be very interesting to see what they say.

Please post if you would like to add to this discussion or you disagree with anything I've said here. I'm not an expert in vitamin D deficiency - I've gleaned this info from what I consider to be reliable sources on the internet. I currently have a a deficiency in vitamin D, found by a routine blood test done by my doctor to check my levels, and I'm taking 2 by 1000IU vitamin D tablets a day.

susan_CNY

my internist agrees with you and this info, my level was tested at 11 she prescribed a 1.5 mg softgel once a week for 8 weeks ( I think equals 50,000 units) and will test the level again next week, I have lost over 50 lbs in a year, I think losing the fat may have depleted my vit d and I have avoided the sun for years now, I really think I am feeling better..My sis passed from multiple sclerosis which is now being linked to low vit d also, as is Crohns disease which is in my family , when my sis was 1st dx her neurologist remarked that Central New York is one of the cloudiest parts of the US and MS is more common for this reason, that was 33 years ago! this seems to have been along time coming unfortunately