It seems that television news broadcasts are constantly advertising a new antioxidant-rich "superfood". They tout the cancer prevention values of antioxidants as if it's a miracle. It's no wonder that cancer prevention is a hot topic in the news. About 25% of deaths in the United States are caused by various forms of cancer. But for all of the talk about antioxidants, I for one, was clueless about what they actually do. What are antioxidants? How do they help prevent cancer?
To understand the function of antioxidants we must first understand what a "free radical" is. As defined by the National Center for Biotechnology Information (NCBI): "...any molecular species capable of independent existence, that contains an unpaired electron in an atomic orbit". Mouthful, I know, but we can focus on one thing as the important bit: the "unpaired electron in an atomic orbit". When a molecule has this unpaired electron, you can think of it as being desperate for a date. It will link up with the first available electron and a reaction will occur. These free radicals donate an oxygen electron to whatever they link with, causing oxidation (in some cases free radicals borrow an oxygen from another molecule, which is also harmful). But isn't oxygen good for you? Of course, but like everything else, it is good where it is needed, and harmful when it's out of place. Free radicals spread oxygen around to places where it's not needed, like to your DNA or the membrane of your cells. When unwanted oxygen is added to those places, the DNA can change how it functions, and the cell can die. This damage to cells is connected to cancer and a number of other diseases. In addition, free radicals can link together, causing high concentrations in small areas. The large amount of cell damage that occurs in concentrated areas attribute to the formation of tumors.
Free radicals are created naturally in the body by things like exercise, injuries, and inflammation. They can also be created by external factors such as cigarette smoke, pollution, radiation, pesticides and other chemical pathogens. That's where antioxidants come in. When free radicals are released, your body uses antioxidant enzymes to neutralize these radicals, and prevent cell damage. Problems occur when the level of free radicals is much higher than the level of antioxidants. When there are no antioxidants to react with, free radicals can react with cells. This is known as oxidative stress and is associated largely with external factors like smoking and radiation. Poor diet can cause high levels of inflammation, which leads to free radical propagation.
Not all of the necessary antioxidants are created in the body. To prevent oxidative stress we need to find outside sources of antioxidants. Vitamin E, Vitamin C, and Beta-Carotene are all antioxidants that are vital to biological function, and can only be acquired through diet. Additionally, Selenium, a mineral that helps the body create antioxidants, can only be obtained by ingestion. Higher levels of antioxidants in the body should help alleviate the damage of oxidative stress caused by free radicals. Unfortunately for smokers, eating a lot of papaya won't prevent lung cancer. Antioxidants can help alleviate oxidative stress. They can't prevent it when free radicals are being produced at unprecedented rates.
To date, a number of studies have been done using Vitamins E, C, and Beta-Carotene supplements on people who either have cancer or are at high risk for cancer. The results can be found here. In most cases, supplements did not help prevent cancer. In some cases, supplementation actually made it worse. This result could be interpreted as "antioxidants are bad for you". But, as with most things, it's more complicated than that. This just shows that highly concentrated supplements are an unhealthy way of ingesting antioxidants.
Antioxidants derived, through digestion of whole foods, may be the key. The Okinawa Centenarian Study, was a 25 year research project, focusing on the Okinawa centenarians (hundred year olds). The goal was to find out why, for centuries, Okinawans were the healthiest and longest lived people in the world. The study showed that Okinawans suffered 57% less death from ovarian cancer, 86% less from prostate cancer, and 82% less from breast cancer than Americans. The reason: food. Okinawans eat a diet rich in whole grains and a wide variety of vegetables and tofu. From the grains come Vitamin E. From the various veggies and legumes come Vitamin C and Beta-Carotene. And finally, soy, which makes up about 99% of tofu's mass, is a great source of Selenium. Their diet also includes far less meat, dairy, and egg. While meat, dairy, and egg contain antioxidants, they do so at lower rates than fruits and vegetables, with a much higher caloric cost. The high levels of antioxidants in the Okinawan diet, and the low rates of cancer, have a strong correlation. The high amounts of fiber in whole vegetables contribute to easier digestion. Good digestive health can greatly reduce free radical causing inflammation in the intestinal tract.
This topic is complex and much is yet to be learned. New information is available all of the time and accessible simply by running an Internet search. Until more is discovered about free radicals and antioxidants, it is hard to say that antioxidants alone are a miracle cure. In fact, studies of antioxidants in supplement form seem to indicate that supplementation can be harmful. One thing that's for sure; fruits and vegetables should make up a large part of dietary calories. For some people, eating this way could represent a difficult departure from usual habits. The results are not only rewarding, they are delicious and satisfying. As I write this, my belly is full of whole grain red rice, papaya, tofu, and herbs. Years ago, I would have turned my nose at these foods. However, with proper seasoning and an open mind, anyone can enjoy the benefits of nutritious whole foods.