Antioxidants and Cancer
Do antioxidants cause cancer?
That’s a suggestion by James Watson, who, along with Francis Crick (with help from research by others as well) determined the double-helical structure of DNA many decades ago. Now Watson has a controversial theory that at least in people with late-stage cancers of a certain kind, antioxidants may be harmful.
I wrote a blogpost about the possible problems of antioxidants in people with diabetes several years ago, and I think there’s probably some truth in what Watson is saying.
When we metabolize our food, the process is not without errors, and we produce not only ATP (the “energy currency” of the cell) but also what are called reactive oxygen species (ROS). These ROS used to be called free radicals.
The ROS are extremely reactive, and when we have too many ROS, they can damage our cells, especially our DNA, our genes. Sometimes they damage the cell so much that the cell commits suicide. Hence our bodies produce antioxidants to keep the ROS in check. Some people say that people with diabetes have fewer antioxidants than others and hence recommend supplementing with antioxidants like vitamin C or vitamin E, or foods high in antioxidants like colorful berries and even coffee.
But there’s another side to this story. Our cells use ROS to destroy pathogens and aberrant cells like cancer cells, and they also use ROS as signaling molecules. Thus if we had no ROS at all, our cells would not function properly.
This is what Watson is trying to say, mostly in the context of late-stage cancer, especially with certain types of cancer like sarcomas and many carcinomas. In such states, he suggests, antioxidants can be harmful.
Watson isn’t the first person to suggest avoiding antioxidants if you have cancer. Some people have recommended that people undergoing chemotherapy avoid antioxidants, although others say that the antioxidants help to prevent side effects.
Coincidentally, a few days after Watson’s paper was published, another paper was published showing that tadpoles need ROS in order to regrow their tails. When the researchers gave them antioxidants, the tails didn’t regenerate. This suggests (but doesn’t prove) that healing in humans might also be slowed down by too many antioxidants, so people with wounds that don’t want to heal might reduce their intake of antioxidants to see if that helped.
Especially interesting for those of us on metformin are Watson’s comments about the cancer-reducing qualities of that drug. He notes that metformin is being added to a number of cancer chemotherapies to see if it will magnify their effectiveness. You can read the full text of his article, but it’s pretty dense.
So what does all this mean for us? Unfortunately, the answer isn’t black and white. As people with diabetes, we seem to have fewer antioxidants than normal, so it’s probably a good idea to get a little extra in our food. But perhaps not too much. Eating a variety of foods is probably a better way to get antioxidants than popping pills, which usually contain just one or a couple of antioxidants, and then perhaps in excess.
This would be especially important if you have cancer, and even more important if you’re getting chemotherapy for that cancer.
Watson’s comments go beyond just not using antioxidants when you already have cancer. He thinks they might cause cancer. He writes, “The time has come to seriously ask whether antioxidant use much more likely causes than prevents cancer.” He then cites research showing that people who supplement with beta-carotene, vitamin A, vitamin C, vitamin E, and selenium “have shown no obvious effectiveness in preventing gastrointestinal cancer. . . . In fact, they seem to slightly shorten the lives of those who take them.”
As Watson said, “blueberries best be eaten because they taste good, not because their consumption will lead to less cancer.”
Remember oat bran? Every product on the shelf seemed to proclaim “Contains oat bran.” Then the tide turned and we saw products saying “Contains no oat bran.” Will we see the same with antioxidants? Will “Contains no antioxidants” be the advertising claim of the future?
Maybe added antioxidants aren’t as good as we thought they were. But I still think getting antioxidants from a variety of foods is beneficial, especially when we have diabetes.
I’d blather on, but I feel the need for an antioxidant-filled cup of coffee right now.
(An aside: I took a couple of courses from Watson when I was in college and once threatened to throw my bluebook in his face if he asked a particular question on the exam. He did. Luckily, he wasn’t present, so I didn’t have to follow through.)