February 8, 2016
356 Antioxidants & Cancer [8 Feb 2016]
Last week I mentioned biomedical scientist Dr. Rhonda Patrick who was interviewed by Dr. Mercola about mitochondria. One of the video lectures on her website (foundmyfitness.com) is titled “Do Antioxidants Cause Cancer?”
Since oxidative damage from free radicals is known to cause cancer, and antioxidants protect us from that damage, it was believed that supplementing with antioxidants should prevent cancer. Research results, however, have been rather disappointing and in some cases found that antioxidants can even increase cancer risk. What’s going on?
Dr. Patrick explains that it is important to understand how antioxidants work and the context of the studies. It is now understood that free radicals play a beneficial role in the cells at low levels and in certain circumstances. One of these is in the role of apoptosis (programmed cell death) of damaged cells to prevent their proliferation into cancer. One study found that supplementing mice with vitamin E prevented DNA damage in the control group (without cancer) but increased the rate of cancer growth in the mice with cancer. The vitamin E prevented the activation of the Tumor Suppressor Genes which would have otherwise killed the cancer cells, and allowed them to proliferate faster. Patrick advised that vitamin E in doses near the RDA (22 IU/day in Canada) is probably beneficial unless you already have cancer in which case it should be avoided.
The Selenium and Vitamin E Cancer Prevention Trial (SELECT) found a statistically increased risk of prostate cancer in men taking alpha tocopherol (400 IU) but not in those also taking selenium (200 mcg). Patrick explains that mega doses of alpha tocopherol depletes levels of another form of vitamin E, gamma tocopherol. Previous studies found the risk of prostate cancer was 5 times higher in men with the lowest gamma tocopherol levels compared with the highest. Gamma, but not alpha, tocopherol acts on a group of free radicals called Reactive Nitrogen Species (RNS) which are involved in prostate cancer. Selenium, as part of a compound called Selenoprotein P, also protects against the RNS free radicals. Patrick’s conclusion: if you supplement with vitamin E, choose one with both alpha and gamma tocopherols, and again stay close to the RDA.
For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.