The Oxygen Radical Absorbance Capacity (ORAC) score was developed by Dr. Guohua Cao, a chemist and physician. It measures the antioxidant levels of food and other chemical substances.

Imagine rust attacking metal. When the rust eats away at the metal, the metal starts to weaken and decay. This is what happens to our body when free radicals attack it. Organs, cells and other parts of the body can be weakened by oxidation. This leads to diseases such as diabetes, cancer, skin and heart diseases, dementia and osteoarthritis.

An antioxidant has the ability to eliminate oxygen free radicals. Oxygen radicals are chemicals that form naturally inside the body through the process of oxidation. Everyday functions, such as digestion and physical activity, produce oxygen radicals. Daily exposure to polluted air, rancid food, radiation from the sun, smoking and a host of other factors also contribute.

The ORAC score measures the antioxidants in foods. Combinations of nutrients found in foods may have greater protective benefits than each nutrient on its own. For that reason, it is recommended that these nutrients be obtained by eating the plants themselves, rather than from supplements in pill or powder form.

Fruits and vegetables have different ORAC scores, depending on their pigments and the number of phytochemicals they contain. Foods with high ORAC scores mean that they are higher in antioxidants than other foods and may be able to protect cells and their components from oxidative damage - meaning the food may be better at helping us fight diseases, such as diabetes, heart disease and cancer.

Studies have shown that eating foods with a high ORAC score will raise the antioxidant levels in the blood by 10% - 25%. In order to have a significant effect on plasma and tissue antioxidant levels, researchers have suggested eating 5,000 ORAC units each day. Eating eight to ten servings of brightly colored fruits and vegetables, or dark greens, will help achieve this level.