Vitamin D No Magic Bullet for Cancer

New research shows vitamin D may not be the cancer cure-all many hoped for.

ByABC News
October 30, 2007, 12:52 PM

Oct. 30, 2007 — -- We have been bombarded over the last couple of years with scientific articles suggesting that vitamin D is the key to improving many aspects of our health, including reducing the risks of dying from cancer.

An article in this week's Journal of the National Cancer Institute reminds us that perhaps we should be a bit cautious in embracing vitamin D as "the answer" before we do more research.

The report, from the National Cancer Institute and the Centers for Disease Control and Prevention, concluded that vitamin D levels in the blood were not related to overall cancer mortality.

However, the study did find that higher levels of vitamin D were associated with a substantial decrease in the risk of dying from colorectal cancer, and possibly with a reduction in the risk of dying from breast cancer.

The study was performed between 1988 and 1994 and was designed to examine the health and nutritional status of the noninstutionalized U.S. population.

A total of 16,818 people were part of the study, which continued with follow-up through the end of 2000.

The researchers monitored a number of factors, including race/ethnicity, the latitude where the people lived (which would be expected to influence vitamin D levels through sun exposure), smoking, educational levels and physical activity, among other variables.

The key finding of the study was that there was no impact of vitamin D levels on the overall risk of dying from cancer, when comparing groups based on where they lived or what season their blood test was drawn.

When the researchers broke down the risks of cancer deaths based on a number of cancer sites, the only significant reduction they found was for colorectal cancer. In this cancer, those people with higher levels of vitamin D had a risk of dying from this disease that was 72 percent less than people with lower levels of vitamin D.

Although the data for breast cancer was suggestive of a protective effect of vitamin D, the numbers were insufficient to rule out other possible explanations for the decreased risk of death from breast cancer noted in the study.