Free Radicals in the Body

Pollution increases exposure to free radicals.
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Free radicals are unstable molecules that can damage the cells in your body. They often occur as the result of normal metabolic processes -- when your body uses oxygen, it creates free radicals as a by-product, and they may cause damage to the cells of the body. This process is called 'oxidative stress.'

But your metabolism isn't the only culprit. You can be exposed to free radicals from various environmental sources such as radiation, drugs, pesticides, solvents, cigarette smoke and other pollutants.

When you're young and healthy, your body does a pretty good job of dealing with these free radicals, and you don't even notice anything. But, if you don't eat right, smoke, or are exposed to a lot of environmental sources of free radicals, your risk for damage goes up. Oh, and aging takes it toll on your free radical defense system too.

Free radicals damage cells so over time, whatever organ those cells belong to isn't going to function quite as well as it should. For example, collagen gets weaker and as a result, your skin gets more wrinkles. And the walls of your arteries can get damaged, and cholesterol plaques build up -- that can reduce blood flow to your heart, brain or other organs, or cause blood clots. 

Excessive free radical damage is associated with an increased risk of many chronic diseases, such as heart disease and some forms of cancer. 

So what does this have to do with nutrition and diet?

Some nutrients such as vitamin C, beta-carotene, selenium and vitamin E may help prevent or reduce the damage caused by free radicals. These nutrients are found in a variety of foods, but they're highest in plant sources. So eating a diet rich in fruits and vegetables is so important - they're naturally high in antioxidants.

And studies show that eating a diet high in antioxidants is associated with better health. Of course, there are other reasons why people who have a high intake of antioxidants might be in better health. For example, they also tend to be more physically active and maintain a proper caloric intake.

Can Dietary Supplements Fight Free Radicals?

There are so many dietary supplements that claim to be antioxidants. But, although eating foods rich in antioxidants appears to be beneficial, taking antioxidant supplements doesn't offer the same benefits, except in rare cases, such as a combination of lutein, zeaxanthin, and other nutrients that seem to slow down the progression of macular degeneration. 

In addition, some studies suggest taking antioxidant supplements can cause more harm than good. So, rather than spend money on dietary supplements, you're better off to buy more fruits and vegetables.

Sources:

Broadhead GK, Grigg JR, Chang AA, McCluskey P. "Dietary Modification and Supplementation for the Treatment of Age-related Macular Degeneration." Nutr Rev. 2015 Jul;73(7):448-62. Accessed February 17, 2016. https://nutritionreviews.oxfordjournals.org/content/73/7/448.long.

Harvard T.H. Chan School of Public Health, The Nutrition Source."Antioxidants: Beyond the Hype." Accessed February 17, 2016. http://www.hsph.harvard.edu/nutritionsource/antioxidants/.

Lobo, V. et al. "Free Radicals, Antioxidants and Functional Foods: Impact on Human Health." Pharmacognosy Reviews 4.8 (2010): 118–126. Accessed February 17, 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/.

National Cancer Institute. "Antioxidants and Cancer Prevention. Accessed February 17, 2016. http://www.cancer.gov/about-cancer/causes-prevention/risk/diet/antioxidants-fact-sheet.

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