Lung cancer and supplementation findings ignite debate

By Clarisse Douaud

- Last updated on GMT

Related tags: Epidemiology, Dietary supplement

The Natural Products Association (NPA) has voiced concern
surrounding findings presented at the American Thoracic Society
2007 International Conference, which indicated no statistically
significant relationships between dietary supplements and lung
cancer.

In a presentation given at the San Francisco conference on Monday, a sub-study from the Vitamins And Lifestyle (VITAL) study isolated the effect of vitamin supplements on lung cancer risk. NPA, however, says this link is not in fact plausible, as the study model used should have been a randomized clinical trial and not a cohort study. These findings show that there is no correlation between any benefits on lung cancer and supplementation. The results add to a tense climate around the subject following a controversial trial demonstrating that antioxidants can actually cause cancer. "People are spending billions of dollars on supplements, and there is a general sense in the population that they prevent cancer,"​ said study researcher Dr. Chris Slatore, from the University of Washington School of Medicine. "We need to find out if they're helpful or even harmful." ​ The sub-study was conducted as part of the larger cohort study conducted in Western Washington State over a period of ten years. It investigated the link between supplement use and cancer risk. The researchers focused on prostate, breast, lung and colorectal cancers, and multivitamins, vitamins C and E, folate, omega-3 fatty acids and fiber. Between 2000 and 2002, 77,738 men and women between the ages of 50 and 76 participated. They answered a baseline questionnaire which included detailed information on their use of 38 different supplements, their diet and exercise patterns, as well as their medical history and pharmaceutical drug consumption. In Monday's presentation, it was revealed that within this study, 393 cases of lung cancer were found. Researchers adjusted results for risk factors such as smoking, age, sex, cancer history, lung disease and history of lung cancer, but say they still found no statistically significant relationships between different types of supplements and lung cancer. ​NPA finds fault with the questionnaire. "A randomized clinical trial is needed before the data can be of any significance to the general population,"​ said Daniel Fabricant, NPA vice president of scientific and regulatory affairs. "The data is ambitious and must be compared with all data outside of the study to accurately reflect the state of the science which the majority demonstrates a positive effect of vitamins E and C and folate on chronic disease."​ The trade association asserts there is no way to confirm that respondents accurately reported their consumption of supplements and medications, or their lifestyle patterns, over a ten year period. At stake is the credibility of the supplement industry as studies linking supplements to disease risk, or pointing to allegedly placebo-like effects of such products, get increased media play. "Drawing a conclusion on chronic disease without all the pertinent information available is ill-considered and potentially misleading to the population,"​ said Fabricant. "Especially considering the potential protective benefit nutrients may have on chronic disease and other forms of cancer." ​A meta-analysis of 68 randomized trials with antioxidant supplements published in the Journal of the American Medical Association in February reported that vitamins A and E could increase mortality by up to 16 percent. The findings were widely publicized in mainstream media and trade associations, and industry advocates found themselves in a position of having to clean up after the bad publicity. Critics again pointed the finger at the ineffectual study model used to come such conclusions - a case of comparing apples to oranges, they said. According to Dr. Slatore, a 1996 study known as the CARET study, encouraged researchers to delve further into the relationship between supplements and lung cancer. That study, examining the effects of the beta-carotene and vitamin A supplementation, was cancelled when the supplements were judged to be increasing lung cancer risk. Source: DiSilvestro R.A, Dy E. "Comparison of acute absorption of commercially available chromium supplements." Journal of Trace Elements in Medicine & Biology​. 2007;21(2):120-4. Epub 2007 Mar 19.

Related topics: Research

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