“Buyer Beware”- Supplements Are Not What They Are Advertised to Be

According to an article authored by Maria Elena Martinez’s (Ph.D., University of California, San Diego) in the Journal of the National Cancer Institute, “Consumers need more information and guidance about the risks as well as the benefits, of using dietary supplements for cancer prevention.” Dr. Martinez states that dietary supplements have little supporting evidence for health benefits in disease prevention – particularly cancer.

“Despite this evidence, marketing claims by the supplement industry continue to imply anti-cancer benefits“ Martinez wrote.  “Insufficient government regulation of the marketing of dietary supplement products may continue to result in unsound advice to consumers. Both the scientific community and government regulators need to provide clear guidance to the public about the use of dietary supplements to lower cancer risk.”

Half of US adults use one or more daily dietary supplements. “Use of supplements has been fueled primarily by marketing oriented claims of wide ranging benefits,” Martinez and her co-authors wrote. “As a result, sales of dietary supplements have grown into a $30 billion a year industry.”

To assess the current status of evidence supporting use of supplements, Martinez and her associates reviewed literature for supplements that have been tested in adequately powered clinical trials or in large, well-designed observational studies.  The review looked at data for the use of antioxidants, folic acid, Vitamin D and calcium to prevent cancer.

Preclinical studies suggested that dietary antioxidants including beta carotene, alpha tocopherol, and Vitamin C encouraged growth of normal cells and tissue and inhibit growth of abnormal tissue. Clinical studies failed to support those ideas:

>  Beta carotene did not prevent recurrence of non melanoma skin cancer

>  Beta carotene, alpha tocopherol and Vitamin C failed to prevent recurrence of colonic adenomas

>  Beta carotene, Vitamin A and alpha tocopherol did not prevent lung cancer

>  Vitamins C and E did not protect against cancer

>  Alpha tocopherol, Vitamin C and beta carotene had no effect on cancer incidence or mortality

>  Vitamins A, C and E with beta carotene alone or in combination did not prevent gastrointestinal cancers

>  Alpha tocopherol and selenium failed to prevent prostate cancer in average risk men

In some instances studies actually showed an increased risk of cancer in those taking supplements.

Two different randomized trials showed an increased risk of cancer (prostate) and pre cancerous lesions (colonic adenomas) in individuals taking long term folic acid supplementation.

The paper was equally negative about Vitamin D use. They cited three short term studies that failed to demonstrate an effect of Vitamin D on cancer incidence or mortality. The authors went on to support the Institute of Medicine position that “there is not enough evidence to state that there is a causal association between low Vitamin D intake and increased cancer risk.”

The material was published in the Journal of the National Cancer Institute and summarized recently in the on line news service MedPage.

In my practice I will continue to emphasize that a balanced diet prepared in a manner to preserve the nutrients is the best way to meet your nutritional needs. I will screen for those malabsorptive states and surgical situations that require supplementation with vitamins and supplements. These are sufficiently rare. In some cases, administration of medications such as anti-cancer agents causes depletion or malabsorption of vitamins and trace elements. In those cases I will supplement.  Women requiring calcium to prevent osteopenia and osteoporosis should be supplemented. In most other instances, I will suggest a balanced diet and correct preparation of food which should provide all the vitamins, minerals and antioxidants needed to stay healthy