Benefits of UV-B Light
Some studies shows that moderate exposure to UV-B light can be beneficial to human health. UV-B rays are the main source of Vitamin D for our bodies. It may be more beneficial to be moderately exposed to UV-B light than to avoid it altogether.
UV-B and Tanning Your Source for Vitamin D
"Vitamin D casts cancer prevention in new light" MARTIN MITTELSTAEDT
Saturday April 28, 2007
For decades, researchers have puzzled over why rich northern countries have cancer rates many times higher than those in developing countries and many have laid the blame on dangerous pollutants spewed out by industry. But research into vitamin D is suggesting both a plausible answer to this medical puzzle and a heretical notion: that cancers and other disorders in rich countries aren't caused mainly by pollutants but by a vitamin deficiency known to be less acute or even non-existent in poor nations. Those trying to brand contaminants as the key factor behind cancer in the West are "looking for a bogeyman that doesn't exist," argues Reinhold Vieth, professor at the Department of Nutritional Sciences at the University of Toronto and one of the world's top vitamin D experts. Instead, he says, the critical factor "is more likely a lack of vitamin D." What's more, researchers are linking low vitamin D status to a host of other serious ailments, including multiple sclerosis, juvenile diabetes, influenza, osteoporosis and bone fractures among the elderly.
The main way humans achieve healthy levels of vitamin D is not through diet but through sun exposure. Not everyone is willing to jump on the vitamin D bandwagon just yet. Smoking and some pollutants, such as benzene and asbestos, irrefutably cause many cancers. But perhaps the biggest bombshell about vitamin D's effects is about to go off. In June, U.S. researchers will announce the first direct link between cancer prevention and the sunshine vitamin. Their results are nothing short of astounding. A four-year clinical trial involving 1,200 women found those taking the vitamin had about a 60-per-cent reduction in cancer incidence, compared with those who didn't take it, a drop so large twice the impact on cancer attributed to smoking it almost looks like a typographical error. And in an era of pricey medical advances, the reduction seems even more remarkable because it was achieved with an over-the-counter supplement costing pennies a day. One of the researchers who made the discovery, professor of medicine Robert Heaney of Creighton University in Nebraska, says vitamin D deficiency is showing up in so many illnesses besides cancer that nearly all disease figures in Canada and the U.S. will need to be re-evaluated. "We don't really know what the status of chronic disease is in the North American population," he said, "until we normalize vitamin D status."
Sunshine vitamin
For decades, vitamin D has been the Rodney Dangerfield of the supplement world. It's the vitamin most Canadians never give a second thought to because it was assumed the only thing it did was prevent childhood rickets, a debilitating bone disease. But the days of no respect could be numbered. If vitamin D deficiency becomes accepted as the major cause of cancer and other serious illnesses, it will ignite the medical equivalent of a five-alarm blaze on the Canadian health front. For many reasons, Canadians are among the people most at risk of not having enough vitamin D. This is due to a quirk of geography, to modern lifestyles and to the country's health authorities, who have unwittingly, if with the best of intentions, played a role in creating the vitamin deficiency. Authorities are implicated because the main way humans achieve healthy levels of vitamin D isn't through diet but through sun exposure. People make vitamin D whenever naked skin is exposed to bright sunshine. By an unfortunate coincidence, the strong sunshine able to produce vitamin D is the same ultraviolet B light that can also causes sunburns and, eventually, skin cancer. Only brief full-body exposures to bright summer sunshine of 10 or 15 minutes a day are needed to make high amounts of the vitamin. But most authorities, including Health Canada, have urged a total avoidance of strong sunlight or, alternatively, heavy use of sunscreen. Both recommendations will block almost all vitamin D synthesis. Those studying the vitamin say the hide-from-sunlight advice has amounted to the health equivalent of a foolish poker trade. Anyone practising sun avoidance has traded the benefit of a reduced risk of skin cancer which is easy to detect and treat and seldom fatal for an increased risk of the scary, high-body-count cancers, such as breast, prostate and colon, that appear linked to vitamin D shortages. The sun advice has been misguided information "of just breathtaking proportions," said John Cannell, head of the Vitamin D Council, a non-profit, California-based organization. "Fifteen hundred Americans die every year from [skin cancers]. Fifteen hundred Americans die every day from the serious cancers." Health Canada denies its advice might be dangerous. In an e-mailed statement, it said that most people don't apply sunscreen thoroughly, leaving some skin exposed, and that people spend enough time outside without skin protection to make adequate amounts of vitamin D. However, the Canadian Cancer Society last year quietly tweaked its recommendation to recognize that limited amounts of sun exposure are essential for vitamin D levels. Avoiding most bright sunlight wouldn't be so serious if it weren't for a second factor: The main determinant of whether sunshine is strong enough to make vitamin D is latitude. Living in the north is bad, the south is better, and near the equator is best of all. Canadians have drawn the short straw on the world's latitude lottery: From October to March, sunlight is too feeble for vitamin D production. During this time, our bodies draw down stores built by summer sunshine, and whatever is acquired from supplements or diet. Government regulations require foods such as milk and margarine to have small amounts of added vitamin D to prevent rickets. Other foods, such as salmon, naturally contain some, as does the cod liver oil once commonly given to children in the days before milk fortification. But the amounts from food are minuscule compared to what is needed for cancer prevention and what humans naturally can make in their skin. Vitamin D levels in Canada are also being compromised by a lifestyle change. Unlike previous generations that farmed or otherwise worked outside, most people now spend little time outdoors. One survey published in 2001 estimated office- and homebound Canadians and Americans spend 93 per cent of waking time in buildings or cars, both of which block ultraviolet light. Consequently, by mid-winter most Canadians have depleted vitamin D status. "We're all a bit abnormal in terms of our vitamin D," said Dr. Vieth, who has tested scores of Canadians, something done with a simple blood test.
How much is enough?
Just how much vitamin D is required for optimum health is the subject of intense scientific inquiry. Dr. Vieth has approached the matter by asking: What vitamin D level would humans have if they were still living outside, in the wild, near the equator, with its attendant year-round bright sunshine? "Picture the natural human as a nudist in environments south of Florida," he says. He estimates humans in a state of nature probably had about 125 to 150 nanomoles/litre of vitamin D in their blood all year long — levels now achieved for only a few months a year by the minority of adult Canadians who spend a lot of time in the sun, such as lifeguards or farmers. For the rest of the population, vitamin D levels tend to be lower, and crash in winter. In testing office workers in Toronto in winter, Dr. Vieth found the average was only about 40 nanomoles/L, or about one-quarter to one-third of what humans would have in the wild. The avalanche of surprising research on the beneficial effects of vitamin D could affect dietary recommendations as well. Health Canada says that, in light of the findings, it intends to study whether recommended dietary levels need to be revised, although the review is likely to be years away. A joint Canadian-U.S. health panel last studied vitamin D levels in 1997, concluding the relatively low amounts in people's blood were normal. At the time, there was speculation vitamin D had an anti-cancer effect, but more conclusive evidence has only emerged since. "There needs to be a comprehensive review undertaken and that is planned," says Mary Bush, director general of Health Canada's office of nutrition policy and promotion. But Ms. Bush said the government doesn't want to move hastily, out of concern that there may be unknown risks associated with taking more of the vitamin. Those who worry about low vitamin D, however, say this stand is too conservative — that the government's caution may itself be a health hazard. To achieve the vitamin D doses used for cancer prevention through foods, people would need to drink about three litres of milk a day, which is unrealistic. If health authorities accept the new research, they would have to order a substantial increase in food fortification or supplement-taking to affect disease trends. As it is, the 400 IU dosage included in most multivitamins is too low to be an effective cancer fighter. Dr. Vieth said any new recommendations will also have to reflect the racial and cultural factors connected to vitamin D. Blacks, South Asians and women who wear veils are at far higher risks of vitamin D deficiencies than are whites. Although humans carry a lot of cultural baggage on the subject of skin hue, colour is the way nature dealt with the vagaries of high or low vitamin D production by latitude. Those with very dark skins, whose ancestors originated in tropical, light-rich environments, have pigmentation that filters out more of the sunshine responsible for vitamin D; in northern latitudes, they need more sun exposure often 10 times as much to produce the same amount of the vitamin as whites. Dr. Vieth says it is urgent to provide information about the need for extra vitamin D in Canada's growing non-white population to avoid a future of high illness rates in this group. Researchers suspect vitamin D plays such a crucial role in diseases as unrelated as cancer and osteoporosis because the chemical originated in the early days of animal evolution as a way for cells to signal that they were being exposed to daylight. Even though living things have evolved since then, almost all cells, even those deep in our bodies, have kept this primitive light-signalling system. In the body, vitamin D is converted into a steroid hormone, and genes responding to it play a crucial role in fixing damaged cells and maintaining good cell health. "There is no better anti-cancer agent than activated vitamin D. I mean, it does everything you'd want," said Dr. Cannell of the Vitamin D Council. Some may view the sunshine-vitamin story as too good to be true, particularly given that the number of previous claims of vitamin cure-alls that subsequently flopped. "The floor of modern medicine is littered with the claims of vitamins that didn't turn out," Dr. Cannell allowed. But the big difference is that vitamin D, unlike other vitamins, is turned into a hormone, making it far more biologically active. As well, it is "operating independently in hundreds of tissues in your body," Dr. Cannell said. Referring to Linus Pauling, the famous U.S. advocate of vitamin C use as a cure for many illnesses, he said: "Basically, Linus Pauling was right, but he was off by one letter."
Vitamin D can be maintained or increased as a result of a tanning session in which the tanning equipment incorporates UVB irradiance.
Up until the introduction of supplements and food fortification, such as that in milk, exposing our skin to UV-B light was the only way our bodies were able to generate Vitamin D. It is still accepted by organizations, such as the U.S. National Institute of Health, that exposure to sunlight remains the most important source of Vitamin D.
Dietary Supplement Fact Sheet
(U.S. National Institute of Health)
Health Canada lists tanning equipment (sunbeds) as a way to increase of maintain Vitamin D levels.
Guidelines tanning equipment (sunbeds) Effect production of Vitamin D3 (Health Canada)
Tanning is associated with optimal Vitamin D status
(American Journal of Clinical Nutrition 2004; 80:1645-9 Tangpricha V, Turner A, Spina C, Decastro S, Chen TC, Holick MF)
Are we becoming Vitamin D deficient?
Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it.
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(European Clinical Journal of Nutrition {(2001) 55, 1091 1097} Vieth R, Cole DE, Hawker GA, Trang HM, Rubin LA.)
Vitamin D Insufficiency in a population of healthy Western Canadians (Canadian Medical Association Journal 2002, 166 (12) Rucker D, Allan JA, Fick GH, Hanley DA.)
Vitamin D Insufficiency among Free-Living Healthy Young Adults Vin Tangpricha, MD, Elizabeth N. Pearce, MD, Tai C. Chen, PhD, Michael F. Holick, PhD, MD, Arn J Med. 2002 Jun 1; 112(8): 659-63
Overview of the proceedings from Experimental Biology 2004 symposium: vitamin D insufficiency: a significant risk factor in chronic diseases and potential disease-specific biomarkers of vitamin D sufficiency. (Calvo MS, Whiting SJ. J Nutr. 2005 Feb; 135(2): 301-3)
Vitamin D and potential related health benefits
The risks and benefits associated with tanning
Tanning, whether by sunlight or sunbed, may cause premature aging of the skin and skin cancer. Exposure to UV-B, whether by sunlight or sunbed, produces Vitamin D in the body. However, mild exposure to UV-B is sufficient. Tanning is not required to generate Vitamin D. Vitamin D levels in the body may be increased by oral supplements without tanning. Increased Vitamin D levels have been associated in some studies with a reduced risk of such conditions as breast, prostate and ovarian cancers, multiple sclerosis, and diabetes. These associations have not been proven conclusively. Further information on Vitamin D and human health is available at Pubmed.com, the site of the United States National Institutes of Health.
Breast Cancer
An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates
Grant WB
Cancer.
2002 Jan 1;94(1): 272-81
Vitamin D and breast cancer risk: the NHANES I Epidemiologic follow-up study,
1971-1975 to 1992. National Health and Nutrition Examination Survey.
John EM, Schwartz GG, Dreon DM, Koo J.
Cancer Epidemiol Biomarkers Prev. 2005 Jul;14(7):1653-9
Prostate Cancer
Residential sunlight exposure is associated with a decreased risk of prostate cancer.
Walsh PC.
J Urol. 2005
Jan; 173(1):87
Vitamin D and prostate cancer prevention and treatment.
Chen TC, Holick MF.
Trends Endocrinol Metab. 2003 Nov;14(9):423-30
Ultraviolet radiation, vitamin D and risk of prostate cancer and other diseases.
Moon SJ, Fryer AA, Strange RC.
Photochem Photobiol. 2005 Nov-Dec; 81(6):1252-60.
Ovarian Cancer
Role of 24-hydroxylase in Vitamin D3 growth response of OVCAR-3 Ovarian cancer cells.
Miettinen S, Ahonen MH, Lou YR, Manninem T, Tuohimaa P, Syvala H, Ylikomi T.
Int J Cancer, 2004 Jan 20; 108(3): 367-73
Induction of Ovarian Cancer cell apoptosis by 1,25-dihydroxyvitamin D3 through the down-regulation of telomerase.
Jlang F, Bao J, Li P, Nicosla SV, Bal W.
J Biol Chem, 2004 Dec 17;279(51):53213-21. Epub 2004 Oct 12.
Growth suppression of ovarian cancer xenografts in nude mice by vitamin D analogue EB1089.
Zhang X, Jlang F, Li P, Li C, Ma Q, Nicosla SV, Bal W.
Clin Cancer Res. 2005 Jan 1;11(1):323-8
Multiple Sclerosis
Variation in the Vitamin D receptor gene is associated with multiple sclerosis in an Australian population.
Tajouri L, Ovcaric M, Curtain R, Johnson MP, Griffiths LR, Csurhes P, Pender MP, Lea RA, J Neurogenet. 2005 Jan-Mar;19(1):25-38.
25-Hydroxyvitamin D levels in serum at the onset of multiple sclerosis. Sollu-Hanninen M, Alras L, Mononen I, Heikkila A, Vlljanen M, Hanninen A, Mult Scler. 2005 Jun;11(3):266-71. Vitamin D and calcium deficits predispose for multiple chronic diseases. Peterlik M, Cross HS. Eur J Elin Invest. 2005 May;35(5): 290-304
Diabetes
Vitamin D and Diabetes
Mathieu C, Gysemans C, Giulletti A, Bouillon R.
Diabetologia. 2005 Jul;48(7):1247-57. Epub 2005 Jun 22.
Vitamin D and type 1 diabetes mellitus: state of the art.
Mathieu C, Badenhoop K.
Trends Endocrinol Metab. 2005 Aug;16(6):261
Vitamin D and calcium deficits predispose for multiple chronic diseases.
Peterlik M, Cross HS.
Eur J Clin Invest. 2005 May;35(5): 290-304.
Does an indoor tan aid in protection from outdoor sunburning?
Effects of repeated sunbed exposures on the human skin. In vivo measurements with confocal microscopy.
(Source Photodermatol Photoimmunol Photomed 2004; 20; 27-31 Gambichler T, Sauermann K, Altintas MA, Paech V, Kreuter A, Altmeyer P, Hoffmann K.
It is important to note that you may achieve a maximum sun protection factor of 2-4 through tanning bed preparation. Health Canada recommends sunscreen with a minimum of SPF of 15 when exposure to the sun is unavoidable. This means that ones skin can spend 2-4 times more time in the sun than normal unprepared skin without sunburning.