High levels of vitamin D can reduce the incidence of cancer by 60 per cent, according to a small study of elderly women in Nebraska published on Thursday. But the number of cancers observed in the 4-year study, reported online in the American Journal of Clinical Nutrition, was small—totalling only 50—leading some experts to question its conclusions. The study, which tracked 1,179 subjects, also looked only at elderly white women, so it is not clear if it applies to other population groups. J Leonard Lichtenfeld, deputy chief medical officer of the American Cancer Society, said the society found the results interesting but not sufficient to recommend that individuals increase their vitamin D intake. However, several large studies have suggested that vitamin D can reduce the risk of colon and breast cancers, and smaller studies have demonstrated a protective effect against prostate, lung and skin cancers. The new study was conducted by Joan Lappe, a professor of medicine at the Creighton University School of Medicine in Omaha. The women in the study had been free of cancer for at least 10 years at the start. Their average age was 67. A third of the women in the study, which was designed to assess bone health, received daily calcium supplements plus 1,100 international units (IU) of vitamin D3, also known as cholecalciferol. Current guidelines for daily vitamin D consumption range from 200 to 600 IU, increasing with age. Another third received only the calcium supplements, while the rest received a placebo. After four years, the group receiving calcium and vitamin D had 13 cancers, while the group receiving calcium alone had 17 and the group receiving placebo had 20. On the assumption that some of the women entering the study might have had a cancer at enrollment, the team looked at the last three years of the study. The results were more dramatic, with a 77 per cent reduction in cancer risk. The women receiving vitamin D had eight cancers, the women receiving only calcium had 15 and the women receiving placebo had 18.
