Het nieuwe medicijn: vitamine D*
Volgens de Engelse onderzoekster Louise Parker, zij is een wereldexpert op het gebied van milieu en kanker, lijkt
vitamine D het nieuwe medicijn of beter gezegd een godendrank te worden in de strijd tegen botontkalking, ms, depressies en tegen kanker. Steeds meer onderzoek toont dit aan alhoewel het hoe en waarom nog niet helemaal duidelijk is en meer onderzoek nodig is.
Wel duidelijk is dat de belangrijkste voedingsbron van vitamine D behalve vis, vette vis en eigeel is de zon. De zon levert duidelijk de meeste vitamine D op doch in grote gedeelte van de wereld, zoals
West-europa krijgt men door de noordelijke ligging niet voldoende zon of men blokkeert de aanmaak door het aanbrengen van zonnecrèmes. Het gevolg is dat veel mensen te weinig vitamine D aanmaken. Louise Parker adviseert daarom dagelijks 25 mcg vitamine D te nemen. Dit is een veilige hoeveelheid die niet met voeding of gezond (zonder te verbranden) zonnen te halen is.
Vitamin D for cancer
It sounds too good to be true ? a little inexpensive pill that could block the development of some cancers, strengthen bones, prevent multiple sclerosis and alleviate winter depression.
But it's not science fiction. The "new aspirin" could be Vitamin D. Just as we discovered that aspirin can guard against heart disease, Vitamin D could become a useful weapon in the fight against MS, osteoporosis, mild depression and one of the most devastating diseases of our time - cancer.
"As time has gone by, Vitamin D has raised its head as a sort of ambrosia for cancers," says Dr. Louise Parker, an epidemiologist and a world expert in the environmental exposures that can lead to cancer. Or, in the case of Vitamin D, the lack of exposure.
"One of the most important sources of Vitamin D is from the sun and through your skin," says Dr. Parker.
"Many parts of Canada don't get much sun in the winter. We've also been telling people to cover up and use sunscreen to prevent skin cancer. Sunscreen actually impairs your (skin's ability) to make Vitamin D."
So the Canadian Cancer Society recommends that during the winter, Canadians take at least 1,000 units a day of Vitamin D, dubbed "the sunshine vitamin." Those units can be contained in a tiny pill that comes in a bottle of 100 tablets ranging from $5 to $10, depending on the brand name.
Dr. Parker says 1,000 units a day is well beyond what you can obtain from your diet. Vitamin D is a bit of a rare vitamin, appearing only in fatty fish, cod liver oil and egg yolks. Even if you were to sunbathe in southern climates, you would not take in 1,000 units.
"If you were to lie naked on a beach in the Bahamas, and I don't recommend that because of skin cancer, you cannot get up to the equivalent of 1,000 units of Vitamin D a day," says Dr. Parker.
She notes Vitamin D as a factor is turning up in study after study. It turns out people with lung and colon cancer are Vitamin D deficient. And it helps the body absorb calcium. In a study examining whether women who took Vitamin D had a lower risk of osteoporosis, it was found the women taking Vitamin D had stronger bones than those who did not take the vitamin. Years later, researchers went back to that study and found that the women who took Vitamin D also had fewer cancers.
But before Vitamin D becomes the "new aspirin," more research needs to be carried out.
Vitamin D works in very complicated ways, she says. It changes the way cells work. In fact, there is medical speculation that it may block cancer cell proliferation or improve immune system functions. But its role is not fully understood.
Lifestyle also has to be part of the equation. Dr. Parker is looking at how obesity, which we know can cause cancer, and exercise, which we know prevents cancer, could interact with Vitamin D.
"At the population level, I am trying to understand how all these things fit together," says Dr. Parker. "It's very complex."
Dr. Parker describes it as looking for a piece of a jigsaw puzzle. "We know some of the jigsaw pieces, but not all," she says.
Meanwhile, there is very little evidence that taking Vitamin D can harm you. Perhaps in huge doses it could cause kidney stones, but that has not been proven.
"On the average, 1,000 units a day is safe and is probably effective in reducing the risk of colon cancer, and maybe other cancers as well," says Dr. Parker.
So does she take Vitamin D and recommend it? Absolutely.
"I take 1,000 units of Vitamin D - one day on and one day off," she says.
Lousie Parker has joined Dalhousie’s Cancer Research Program from Newcastle University in England.
She has done research into the epidemiology of childhood cancer and was principal investigator on a large study of the health of children of radiation workers at one of the oldest nuclear reprocessing facilities in the world – Sellafield in northern England.
Dr. Parker joined Dalhousie’s Department of Community Health and Epidemiology in 2006. She recently became the QEII-Canadian Cancer Society, Nova Scotia Division, Chair in Population Health Cancer Research.
She is jointly appointed with the Faculty of Medicine’s Department of Pediatrics and the Canadian Centre for Vaccinology.
http://www.dal.ca/ (Maart
2008)
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