Antioxidant"" is practically a magic word these days. Advertisers proudly promote products containing these substances, while some studies have proposed antioxidants might help prevent diseases, including some types of cancer. Whether antioxidants can help the body fight cancer is not yet known for sure, but research does suggest eating foods known to contain antioxidants offers other health benefits.
Oxidation itself is a natural process, but antioxidants step in to protect the body from damage for only a small amount of cases.
""Because we live in an atmosphere of oxygen, which is actually very poisonous [because it is a waste product of plants], animals through evolution have used oxygen for respiration,"" said Michael Pariza, UW-Madison professor of Food Science and director of the Food Research Institute. ""But it also reacts with things in our body.""
According to Pariza, an example of oxygen reacting with food is when meat becomes rancid. A process similar to this can also occur in the body.
According to the National Cancer Institute, in a small amount of cases, the oxygen molecule becomes electrically charged, turning into a free radical, which can then hurt other molecules within the body.
""Over time, such damage may become irreversible and lead to disease including cancer,"" according to the institute's website. ""Antioxidants are often described as 'mopping up' free radicals, meaning they neutralize the electrical charge and prevent the free radical from taking electrons from other molecules.""
Janice Antoniewicz-Werner, registered dietician with Dean Health System, said fruits and vegetables generally provide antioxidants like vitamin C while vegetable oils, nuts, leafy greens and fortified cereals are often good sources of vitamin E. Brazil nuts, meanwhile, are good sources of selenium, which is not technically an antioxidant but a component of an antioxidant.
""There's no one perfect food,"" Antoniewicz-Werner said. ""The more variety you get, the more likely you're getting adequate sources of antioxidants.""
She also recommends getting antioxidants from food rather than supplements, which, she said, some studies suggest could actually be detrimental.
It's also a good idea to eat a variety of fruits and vegetables because the benefits of antioxidants vary based on how the food is processed and how fresh it is since some antioxidants decline over time, she said. An orange that contains vitamin C but is not fresh may not provide the same benefit as one that is fresh, for instance.
Some laboratory studies have indicated that the value of antioxidants reaches beyond simply being good for your body. These studies suggest antioxidants may help prevent the development of cancer.
The American Cancer Society estimated that in 2006 26,390 Wisconsin residents would be diagnosed with cancer, a rate of 72 each day. If something as simple as consuming foods containing antioxidants could help, many people would benefit.
The National Cancer Institute, though, states recent clinical trials ""reached inconsistent conclusions"" on the possible effects of antioxidants on cancer prevention.
""The precise relationship between antioxidants and cancer [prevention] is still pretty murky,"" Pariza said. ""There are good reasons for consuming food with vitamin C and other antioxidants, but there are a lot of things in those foods that reduce your risk of cancer, not just antioxidants.""
For example, fiber may help reduce the risk of colon cancer, but it is not clear whether that is actually due to the benefits fiber offers the immune system, making it more capable of catching cells before they become cancerous, Pariza said.
""If you have a compound in food that is an antioxidant and also happens to reduce cancer, the reason it's reducing cancer may be due to more than the fact that it's an antioxidant,"" he said.
Meanwhile, Antoniewicz said, while some types of cancer can be helped by consuming antioxidants, others are not affected.
While research suggests antioxidants might help prevent cancer, there are more reliable ways to prevent cancer-causing free radicals based on the knowledge and studies we currently have. Among the actions people can take: They should avoid ""burning processes"" like cigarette smoke and ultraviolet light from tanning beds, eat a healthy, well-balanced diet and exercise, Pariza said. These actions can help your immune system stay healthy and as a result help reduce your cancer risk, he said.
According to the American Cancer Society, having a healthy diet that includes many servings of fruits and vegetables along with regular exercise can also help prevent obesity, which increases the risks of diseases, including lung and colon cancer, among others.
So while consuming foods rich in antioxidants will likely benefit your health, the full value of antioxidants and their role in cancer prevention remains a mystery. But it couldn't hurt to add more antioxidant-rich fruits and vegetables into your diet.
""There's no harm from eating food [high] in antioxidants,"" Antoniewicz-Werner said. ""It's one of those things that if it may help, why not?""
Foods with high levels of antioxidants
Antioxidants are abundant in fruits and vegetables, as well as in other foods including nuts, grains, some meats, poultry and fish. The list below describes food sources of common antioxidants.
Beta-carotene is found in many foods that are orange in color, including sweet potatoes, carrots, cantaloupe, squash, apricots, pumpkin and mangos. Some green leafy vegetables including collard greens, spinach and kale are also rich in beta-carotene.
Lutein, best known for its association with healthy eyes, is abundant in green, leafy vegetables such as collard greens, spinach and kale.
Lycopene is a potent antioxidant found in tomatoes, watermelon, guava, papaya, apricots, pink grapefruit, blood oranges and other foods. Estimates suggest 85 percent of American dietary intake of lycopene comes from tomatoes and tomato products.
Foods rich in vitamin A include liver, sweet potatoes, carrots, milk, egg yolks and mozzarella cheese.
Vitamin C, also called ascorbic acid, can be found in high abundance in many fruits and vegetables and is also found in cereals, beef, poultry and fish.
Vitamin E is found in almonds, in many oils including wheat germ, safflower, corn and soybean oils and also in mangos, nuts, broccoli and other foods.
Source: ""Antioxidants and Cancer Prevention: Fact Sheet,"" National Cancer Institute
