Study shows vitamin D3 reduces risk of certain cancers

SAN DIEGO A new study looking at the relationship between vitamin D serum levels and the risk of colon and breast cancer across the globe has estimated the number of cases of cancer that could be prevented each year if vitamin D3 levels met the target proposed by researchers, the University of California, San Diego, announced last month.

Cancer prevention specialists at the Moores Cancer Center at UCSD estimate that 250,000 cases of colorectal cancer and 350,000 cases of breast cancer could be prevented worldwide by increasing intake of vitamin D3, particularly in countries north of the equator.

"For the first time, we are saying that 600,000 cases of breast and colorectal cancer could be prevented each year worldwide, including nearly 150,000 in the United States alone," stated study co-author Cedrric Garland.

The paper, which looks at the dose-response relationship between vitamin D and cancer, was published in the August edition of the journal Nutrition Reviews.

The study combined data from surveys of serum vitamin D levels during winter from 15 countries. It is the first study to look at satellite measurements of sunshine and cloud cover in countries where actual blood serum levels of vitamin D3 had also been determined. The data were then applied to 177 countries to estimate the average serum level of a vitamin D metabolite of people living there.

The data revealed an inverse association of serum vitamin D with risk of colorectal and breast cancer. The researchers maintain that increasing vitamin D levels in populations, particularly those in northern climates, has the potential to both prevent and possibly serve as an adjunct to existing treatments for cancer.

"This could be best achieved with a combination of diet, supplements and short intervals – 10 or 15 minutes a day – in the sun," Garland said. The serum level recommended by the study would correspond to intake of 2000 International Units per day of vitamin D3 for a meaningful reduction in colorectal cancer. The researchers recommend 2000 IU/day, plus, when weather allows, a few minutes in the sun with at least 40 percent of the skin exposed, for a meaningful reduction in breast cancer incidence, unless the individual has a history of skin cancer or a photosensitivity disease.