CRN Reacts to New Study Showing Lung Cancer Progression in Mice

A study was published that found that supplementing the diet wit the antioxidants N-acetylcysteine (NAC) and vitamin E increased tumor progression and reduced survival in mouse models of B-RAF and K-RASinduced lung cancer (Sci Transl Med 2014 Jan;6(221): 221ra15).The Council for Responsible Nutrition (CRN) vice president of scientific and regulatory affairs, Duffy MacKay, N.D., commented on the findings.

This animal study used mega-doses of vitamin E on mice that were genetically modified to be predisposed to fast-growing cancer, generating what should have been another hypothesis worthy of discussion among scientists, but instead resulted in a rash of scare-mongering headlines that dont reflect the weight of the studys findings," MacKay said.

The mice, which were genetically engineered to develop fast-growing tumors, were given about 90 to 450 times the recommended amount of vitamin E for consumers to avoid deficiency, according to MacKay.

" The U.S. Preventive Services Task Force (USPSTF) recently evaluated and reaffirmed the safety evidence for vitamin E, stating on its website report, The USPSTF found adequate evidence that supplementation with vitamin E has little or no significant harms.  A study last month published in JAMA on vitamin E in mild to moderate Alzheimers patients not only found potential benefits for vitamin E in this area, but also found no significant increase in mortality with vitamin E' (JAMA. 2014;311(1):33-44). This new mouse study in no way tips the scales of safety," MacKay said.

Similar studies have shown that vitamin E can actually shrink lung cancer tumors in mice. A study from 2005 found that dietary supplementation with NAC slowed the growth of lung cancer in mice (Nature Medicine 2005 Nov;11: 1306-13).

Alex Schauss, Ph.D., senior research director, natural and medicinal products research, for AIBMR Life Science, Inc., a member company of the Natural Products Association, also commented on the findings.

"I hope by contrasting the results of the two papers and pointing out significant differences in between the two studies, it would mitigate the temptation to reach any conclusions that might contradict the wealth of epidemiological and experimental evidence in support of supplementation with antioxidants," Schauss said.

A 2009 study also found that gamma-tocopherol-enriched tocopherol mixture (gammaTmT) inhibited the growth of tumors in mice after five days, with stronger results after 50 days (Mol Nutr Food Res. 2009 Aug;53(8):1030-5).

"New scientific discoveries occur on a daily basis, and are often, like this study, worthy of further consideration. But when the headlines dont place research in the proper context, healthy people may be distracted from getting the recommended amount of vitamin E in their daily diet, whether through food, or supplements, or a combination. Government reports indicate that for most adults there are vitamin E shortfalls in the diet. For the average healthy person taking vitamins, this study is irrelevant," MacKay said.