Ask the Expert: Supplements

The Physicians Committee

Ask the Expert: Supplements

Q: Do you recommend taking dietary supplements or eating fortified grain products?

A: Dietary supplements are increasing in popularity and often come with a variety of health claims. It is important to consider, however, that no single supplement can replicate all the healthy components found in a variety of whole plant foods, including those that ward off cancer. Vegetables, fruits, whole grains, and legumes are packed with lots of healthful substances beyond vitamins, such as fiber, minerals, and cancer-protective phytochemicals. Increasing your fruits and veggies can be almost as simple as popping a pill, and is far more beneficial. If you consume any isolated nutrient in excess, there is always the potential to do harm. An example of this may be with the nutrient folate. Folate has been shown to be a very important nutrient for cancer prevention. Folate helps to repair DNA, which could potentially lead cancer later on in life.

In a recently published Swedish study evaluating folate intake of 11,699 postmenopausal women from the Malmö Diet and Cancer cohort, folate intake was correlated with a lower risk of invasive breast cancer. In the study, women who consumed an average 456 micrograms of folate per day from whole foods (only 19% of women reported using supplements) had a 44 percent lower risk of breast cancer than women in the lowest average intake group (160 micrograms of folate per day).

Lately there has been some concern about the safety of folic acid when consumed in access. Some epidemiologists believe that folic acid fortification in grains has led to the rise colon cancer incidence over the past decade. Folic acid is the oxidized, form of folate and is found in vitamin supplements and enriched and fortified food products.

In the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) study, a high folate status(>853 µg/d), due to supplementation, was found to be potentially harmful rather than beneficial in breast cancer development. The reasoning may be due to the fact that after cancer has been initiated, folate may serve as a growth factor, accelerating the spread of the disease. Folate is important for cells and tissues that rapidly divide. Since Cancer cells divide rapidly, many cancer drugs such as Methotrexate are designed to interfere with folate metabolism, thus slowing cancer growth.

Excess folic acid intake not only may contribute to cancer after it starts, but it may also mask a Vitamin B-12 deficiency. Many adults 50 and over have trouble absorbing and getting enough B-12. Vegans especially need to be aware of this issue. T he take home message is that The Cancer Project promotes a plant based diet rich in whole foods. Whole foods are not fortified or enriched with folic acid or other nutrients. The potential harm of exceeding the upper limits of folic acid from enriched grains seems to be a valid concern, and the repercussions may still be unknown.

Mason JB, et al. A Temporal Association between Folic Acid Fortification and an Increase in Colorectal Cancer Rates May Be Illuminating Important Biological Principles: A Hypothesis. Cancer Epidemiol Biomarkers Prev. 2007;16(7):1325-1329.

Ericson U, et al. High folate intake is associated with lower breast cancer incidence in postmenopausal women in the Malmo Diet and Cancer cohort. Am J Clin Nutr. 2007; 86(2):434-443.