People with higher levels of vitamin D in their bodies are 72 percent less likely to die from colorectal cancer, according to a new study published in the Journal of the National Cancer Institute. Colorectal cancer kills approximately 50,000 people in the United States per year.
Researchers tracked the health status of 16,818 people in a nationwide government health survey. Participants joined between the years of 1988 and 1994 and were followed until the year 2000. Their blood was measured regularly to determine their bodies' levels of vitamin D. Those with higher levels of vitamin D at the beginning of the study were 72 percent less likely to die from colorectal cancer than those who began the study with the lowest levels of the nutrient.
Vitamin D is produced by the body when ultraviolet radiation from the sun strikes the skin. This means that deficiency can be a serious health problem in northern latitudes, particularly during the winter. For this reason, many milk products and non-dairy milk substitutes are fortified with the vitamin. Certain fatty fishes, such as salmon, are naturally high in vitamin D.
Deficiency in vitamin D can lead to rickets, a condition characterized by soft, weak bones, particularly in children.
Prior research has indicated that in addition to acting as an essential nutrient, vitamin D may inhibit the growth of tumors or even kill cancerous cells.
In an accompanying editorial, National Institutes of Health experts Cindy Davis and Johanna Dwyer warned that vitamin D supplementation is not the end-all of cancer prevention.
"While vitamin D may well have multiple benefits beyond bone, health professionals and the public should not, in a rush to judgment, assume that vitamin D is a magic bullet and consume high amounts of vitamin D," they wrote. "More definitive data on both benefits and potential adverse effects of high doses are urgently needed."
Vitamin D can be toxic in high concentrations, but toxicity cannot result from sunlight exposure, because the body ceases production when the needed bodily levels have been reached.