Vitamin D and calcium do not prevent breast cancer

Here is another study from the Women’s Health Initiative that gives disappointing results. At least disappointing for those who are big fans of vitamins and other dietary supplements.

Previous studies suggested that vitamin D supplements may lead to a reduction in breast cancer risk. The current research by UCLA researchers looked at 36,282 postmenopausal women who were randomly assigned to two groups. One group took a pill containing 1,000 mg of calcium plus 400 IU of vitamin D every day while the other group took placebo which was identical in appearance to the vitamin pill. This way, the participants were not aware which drug they were taking. The study was originally designed to study the effects of supplements, especially calcium on the incidence of hip fractures. Fractures due to osteoporosis are quite common among women of postmenopausal age and calcium supplements are prescribed as primary care preventive measure. Vitamin D is also known to contribute to bone health and prevent rickets.

Unfortunately, the main findings of the study say

Calcium and vitamin D supplementation did not reduce invasive breast cancer incidence in postmenopausal women. In addition, 25-hydroxyvitamin D levels were not associated with subsequent breast cancer risk. These findings do not support a relationship between total vitamin D intake and 25-hydroxyvitamin D levels with breast cancer risk.

This wasn’t the first disappointing news regarding vitamin supplementation and cancer. Late last year, the National Cancer Institute prematurely stopped the SELECT trial which investigated the efficacy of selenium and Vitamin E in preventing prostate cancer – with negative results.

There have been many reports that vitamins and other nutritional supplements do not necessarily give us health benefits. Many health experts discourage the use of supplements with the exception perhaps of vitamin D. The American Academy of Pediatrics, for example, revised its guidelines last year to double the dose of vitamin D supplements for children to prevent vitamin D deficiency and rickets. This is in addition to the fact that baby formula and milk products in the US are fortified with vitamin D.

Recent research studies are putting a question mark on the benefits of vitamin supplementation and the current study also puts to doubt the necessity of vitamin D supplements, which taken in excessive amounts, can actually be toxic.

The Consumer Healthcare Products Association (CHPA) has compiled some facts and figures on supplementation, as given below:

In 2004, 18.9 percent of Americans reported that they had taken one or more dietary supplements in the past year. (Institute of Medicine)

The global self-medication market grew 7.4 percent in 1998 – dietary supplements were the fastest growing category with a 16 percent increase. (IMS HEALTH, 1999)

Retail and non-retail sales of dietary supplement products across all distribution channels in the U.S. were $17 billion in 2000. Retail sales of dietary supplement products were approximately $11.3 billion in 2000. (The Nutrition Business Journal, 2001)

The United States leads the world in dietary supplement usage with 100.4 million Americans using vitamin and minerals every day and 37.2 million using herbal remedies regularly. (Prevention Magazine, 2000)

The most prevalent reason consumers use dietary supplements is to improve overall health and general well being. (Roper Starch Worldwide, 2001)

By sales, the two leading categories of supplements are “general health” and “sports/energy/ weight-loss” with $4.4 billion and $4.7 billion respectively. (The Nutrition Business Journal, 2001)