Reexamination of data relating to over 15,000 people has cast doubt on claims that increased vitamin D intake may reduce cancer mortality rates.Previous studies have suggested that high vitamin D consumption may reduce the likelihood of contracting various cancers and other diseases, prompting calls for greater supplementation.Published yesterday in the Journal of the National Cancer Institute, the latest study calls these findings into question, concluding that there is no general link between vitamin D and the risk of death from cancer.Scientists at the National Cancer Institute in Maryland examined the relationship between circulating blood levels of Vitamin D and cancer mortality among the 16,818 participants aged 17 and older in the third national Health and Nutrition Examination Survey.A decade after the survey began, 536 participants had died of cancer but on a general level no connection was found between the deaths and vitamin D levels.However, the data did indicate that high levels of the vitamin (80 nmol/L or more) reduced the risk of dying from colorectal cancer by 72 per cent.The authors of the study said knowledge of the benefits and limitations of vitamin D is currently insufficient to recommend its use for the prevention of disease or death.In an editorial accompanying the analysis, Cindy Davis and Johanna Dwyer said: "These findings must be put into the context of total diet and lifestyle."There are many risk factors other than diet for colorectal cancer, and there are many dietary risk factors other than vitamin D that have been linked to cancer risk."Several studies have previously suggested that vitamin D can reduce cancer mortality by decreasing cancer incidence or improving patients' chances of survival.On a cellular level, scientists have suggested that Vitamin D reduces tumor growth and provokes cancer cell death.While the existence of a connection between vitamin D and cancer mortality remains in question, vitamin D deficiency has been linked to several health problems including cancer.A meta-analysis, published in Archives of Internal Medicine in September, of 18 previous studies involving a total of 57,311 participants indicates that vitamin D deficiency increases the risk of death from cancer, heart disease and diabetes.In another recent study, researchers said the recommended intake of vitamin D is 2000 IU per day whereas the mediam adult daily consumption in the US is 230 IU. Vitamin D is unusual among vitamins in that it is absorbed through exposure to sunlight as well as food.Deficiency of vitamin D is therefore of particular concern in cooler climates where a lack of sunshine means people absorb lower levels of the so-called sunshine vitamin.
