Antioxidant Supplements and Cancer Risk

I try to keep current on any new developments in immunology, and this study came across my study group yesterday:

• [Antioxidants accelerate lung cancer progression in mice.]

Abstract:

Quote:

Antioxidants are widely used to protect cells from damage induced by reactive oxygen species (ROS). The concept that antioxidants can help fight cancer is deeply rooted in the general population, promoted by the food supplement industry, and supported by some scientific studies. However, clinical trials have reported inconsistent results. We show that supplementing the diet with the antioxidants N-acetylcysteine (NAC) and vitamin E markedly increases tumor progression and reduces survival in mouse models of B-RAF- and K-RAS-induced lung cancer. RNA sequencing revealed that NAC and vitamin E, which are structurally unrelated, produce highly coordinated changes in tumor transcriptome profiles, dominated by reduced expression of endogenous antioxidant genes. NAC and vitamin E increase tumor cell proliferation by reducing ROS, DNA damage, and p53 expression in mouse and human lung tumor cells. Inactivation of p53 increases tumor growth to a similar degree as antioxidants and abolishes the antioxidant effect. Thus, antioxidants accelerate tumor growth by disrupting the ROS-p53 axis. Because somatic mutations in p53 occur late in tumor progression, antioxidants may accelerate the growth of early tumors or precancerous lesions in high-risk populations such as smokers and patients with chronic obstructive pulmonary disease who receive NAC to relieve mucus production.

This is consistent with the body of literature to date. Both the biochemistry and in vitro research strongly imply that antioxidant supplementation carries a risk of increased cancer.



There are a few human studies that show the same effect, *but* those studies were not designed to look for that effect, and so I hesitate to say there are human studies that actually show this effect.



So, this is my question: does anybody on the list with the appropriate qualifications think I'm out to lunch by saying it's time to shift antioxidant supplementation from the 'what's the harm' category to the 'proven harmful' category?

via JREF Forum http://ift.tt/MF9NcM