Just about everywhere you look, you find someone touting the benefits of antioxidants. These compounds have come center stage because of their purported ability to protect the human body from diseases like cancer and cardiovascular disease. But exactly what are antioxidants and are they really as potent a preventative as some scientists suggest?

To understand what an antioxidant does, it is necessary to backtrack a bit and look at the relationship between cells and molecules. The cells in the human body are made up of many different kinds of molecules. Each molecule contains a number of different types of elements that are composed of atoms. The atoms that make up each element are joined together by chemical bonds.

Atoms consist of a nucleus, neutrons, protons and electrons. The number of protons, or positively charged particles, in the atom’s nucleus determines the number of electrons, or negatively charged particles that surrounds the atom. Electrons are especially important because they play a role in the chemical reactions that take place within a cell. They are also the substance that bonds atoms together to form molecules. Electrons revolve around an atom in one or more shells.

The number of atoms in its outermost shell decides how an atom behaves chemically. If the atom’s outer shell is full, it usually doesn’t enter into chemical reactions, which means it remains stable. Atoms work to fill their outer shells and reach stability either by gaining or losing electrons, or by sharing electrons through bonding together with other atoms.

When atoms bond, the bonds normally don’t split, which would leave one of the electrons without a mate. However, sometimes a weak bond will split creating an electron that stands alone. This electron is called a “free radical.” A free radical is very unstable and it reacts quickly with other compounds to try to steal the necessary electron it is missing so that it can become stable again. Free radicals hunt down the nearest stable molecule and attack it for its electron. When the molecule that was attacked loses its electron, it then becomes a free radical, and this starts a chain reaction. Once the process is started, it results in the disruption of a living cell.

Some free radicals are a normal byproduct of metabolism. However, factors such as pollution, cigarette smoke and herbicides can also create free radicals. If the production of free radicals becomes too great, damage to the cell can occur.

Antioxidants stop the free radicals from stealing electrons by donating one of their own. Even though the antioxidants give up an electron, they don’t become free radicals because they are stable in either form. They act as scavengers, finding free radicals and making them stable, which prevents cell and tissue damage that could lead to disease.

Humans get antioxidants from three sources. The first source is the natural antioxidants your body produces like gluthathione, which protects cells from toxins and superoxide dismutase that breaks down superoxide into oxygen and hydrogen peroxide, which stops it from causing damage to cells. Another source of antioxidants is found in foods like fruits and leafy green vegetables. Antioxidants that are present in these foods include Vitamins A, C, E and carotenoids. You can generally identify a food rich in antioxidants by its vibrant color such as the red of cherries and tomatoes, the orange of carrots and the bluish-purple of grapes. Humans also get antioxidants by taking vitamin supplements.

According to Dr. Ishwarlal Jialal, Professor of Internal Medicine and Pathology at UC Davis and a recognized leader in antioxidant research, in spite of the fact that the body produces natural antioxidants, you still need a diet rich in antioxidants. This is especially important as you age because your body produces less of the natural antioxidants. He recommends eating 5 to 7 servings of fruits and vegetables daily. He also suggests taking a multi-vitamin supplement that contains 200 milligrams of Vitamin C and 200 to 400 milligrams of Vitamin E.

What specifically has research shown antioxidants to be beneficial against? Antioxidants have been linked to a reduction in the development of cardiovascular disease. LDL or “bad cholesterol” damages the lining of your arteries when it becomes oxidized and this damage is what leads to cardiovascular disease like heart attacks or strokes. Vitamin C, E and beta carotene are believed to protect against the oxidation of LDL. Evidence from a large number of studies also suggests that a diet rich in Vitamin C and beta carotene reduces the risk of virtually all types of cancers.

Antioxidants are also important in the prevention of cataracts. A cataract is a clouding of the eye’s lens that results from a change in the lens’ chemical composition. Most people over age 60 have some degree of lens clouding. Scientists believe that cataracts develop partially as a result of the oxidation of proteins in the lens of your eye. Vitamin C, E and beta carotene may help prevent some lens clouding by neutralizing the free radicals created during this oxidation process.

And those are just a few of the health benefits antioxidants provide. As consumers look for more natural alternatives for maintaining good health, science will meet the challenge by investigating the properties of compounds like antioxidants to discover the as yet untapped healing powers they contain.

FoxNews.com writer Maria Esposito contributed to this report.

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Dr. Manny Alvarez is the managing editor of health news at FOXNews.com, and is a regular medical contributor on the FOX News Channel. He is chairman of the Department of Obstetrics and Gynecology and Reproductive Science at Hackensack University Medical Center in New Jersey. Additionally, Alvarez is Adjunct Professor of Obstetrics and Gynecology at New York University School of Medicine in New York City.

Dr. Manny Alvarez serves as Fox News Channel's senior managing health editor. He also serves as chairman of the department of obstetrics/gynecology and reproductive science at Hackensack University Medical Center in New Jersey. Click here for more information on Dr. Manny's work with Hackensack University Medical Center. Visit AskDrManny.com for more.