The sunshine vitamin made headlines in recent years because of research saying it may be a powerful cancer fighter. It further lead to the latest vitamin craze in a large number of people, with many of them consuming more than currently recommended amounts, either through diet or sun exposure.
Previous animal and cell studies suggest that vitamin D may reduce tumor growth and induce cancer cell death. Diet and exposure to sunlight are the major sources of vitamin D.
Researchers at the National Cancer Institute analyzed vitamin D levels measured in almost 17,000 people as part of a national study that tracked their health. About a decade after enrolling, 536 of those people had died of cancer.
Writing in Tuesday's Journal of the National Cancer Institute, researchers noted that cancer deaths was not related to the level of circulating vitamin D for the overall group. Nor was it related when the researchers looked at the data by sex, race, or age.
However, higher levels of vitamin D were associated with a 72 percent reduced risk of colorectal cancer mortality, compared with lower levels.
"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 possible dietary risk factors other than vitamin D that have been linked to cancer risk," the authors conclude.
Authors also believe that they still need some further studies in this field to see if other vitamins have any role in cancer prevention.
