The faith in vitamin D being able to counteract cancer is greatly increasing. Among other things, it is founded on the well-known normalizing effect of the vitamin on cells and tissues. Another reason is the fact that the incidence of breast cancer, prostate cancer, and colon cancer, for example, is considerably higher in countries such as the UK where the sunlight is scarce and where the sun is so low from September to May that we do not produce any vitamin D in our skin. In addition to this, our diet almost completely lacks sources of vitamin D - the exception being fatty fish.
With regard to breast cancer, the hypothesis was supported about a year ago when British scientists demonstrated that women who have a hereditary defect causing vitamin D to be poorly utilized will also have a doubled risk of developing breast cancer. At the same time, it was established that women with a low vitamin D status have a quadrupled risk of developing lumpy breasts which is a known risk factor in the development of breast cancer.
An American study including 456 patients with early stages of the most common (non-small cell) type of lung cancer now shows that the vitamin D status might also be related to lung cancer. The lung cancer patients who were operated during the summer months in which the stores of vitamin D are the largest had a far better outcome in the study compared to the ones who were operated in the winter.
After five years, 70% of the patients operated in the summer were still symptom-free while the same thing was the case in only 54% of the patients operated in the winter. When the patients' blood levels of vitamin D were taken into consideration, the difference was even greater: 83% of the patients operated in the summer who also had a high vitamin D status were still symptom-free after five years while the same was the case in only 30% of the patients who had a low vitamin D status and were operated during the winter.
It goes without saying that you should not wait six months to have an operation on this account if you are diagnosed with lung cancer in the winter. However, the study gives rise to the question of whether lung cancer patients - and smokers - would be wise to increase their intake of vitamin D.
Much more vitamin D
Thus far, it has been officially recommended that everyone gets at least 5 mcg. of vitamin D a day through the diet. However, most people do not get this amount of vitamin D. It is even more difficult for the elderly who are recommended to get 10 mcg. of vitamin D a day; this is still the recommendation for anyone over 60 years of age.
It will be close to impossible for the nursing home residents to live up to the recent recommendations of taking 20 mcg. of vitamin D a day. This is almost impossible to do without taking a dietary supplement. In an ordinary vitamin pill there is the completely insufficient amount of 5 mcg. - or what equals 50 - 60 g. of fatty fish. Only a very small minority of the residents eat half a pound of fish a day.
According to a number of scientists involved in vitamin D research, not even this amount is sufficient. The estimated safe daily upper limit of vitamin D intake is 50 mcg. although some scientists recommend 100 mcg. a day prophylactically to individuals who are particularly predisposed to cancer and to patients suffering from certain neurological diseases.
The majority of scientists, however, believe that a daily vitamin D intake of 25 mcg. - the equivalent of 10 ml. of cod-liver oil - should be the standard recommendation for all adults. Almost regardless of which recommendation in chosen, the dose cannot be achieved without a supplement.
In the meantime, research is continued at full speed. Japanese scientists have established that substances closely related to vitamin D inhibit both the spreading of lung cancer as well as the formation of new blood vessels inside the tumours.
Other scientists have established that vitamin D promotes cell death or normalizes abnormal cells in a number of tumours; both in the laboratory and in animal tests. Moreover, positive results have been achieved in men suffering from prostate cancer where the traditional anti-hormonal treatment has ceased to work.
One thing seems to be certain: That you should certainly avoid sunburn, but not uncritically trust the warnings of many years' standing from dermatologists about avoiding sunlight at - almost - all costs. If you do, you might risk developing cancer.
References:
American Association for Cancer Research. Press release 18.04.05.
Trump DL et al. Anti-tumor activity of calcitriol: pre-clinical and clinical studies. J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):519-26.
Nakagawa K et al. 22-oxa-1{alpha},25-dihydroxyvitamin D3 inhibits metastasis and angiogenesis in lung cancer. Carcinogenesis. 2005 Feb 17;[Epub ahead of print].
