What’s an antioxidant vs. what is an antiradical?
You may be aware that squeezing lemon or lime juice on a salad or fruit salad will keep it from oxidizing or turning brown. In a sense, the lemon or lime juice is like an antioxidant to prevent your body from oxidizing or turning brown. Antioxidants are the anti agers of the nutrient world working to protect your body from oxidative stress. It is estimated that every cell in our body takes 10,000 oxidative hits to its DNA daily! These hits can come from chemicals in our environment, breathing, or from sunlight. It is antioxidants that work to counteract that damage caused by free radicals. Antioxidants and antiradicals are found mostly in fruits and vegetables such as berries, broccoli, spinach, and green tea. These antioxidants protect plants and consequently us, when we consume them.
Antiradicals are molecules that neutralize free radicals in our bodies. Free radicals are highly reactive and short-lived uncharged molecules that have an unpaired electron. Since electrons like to be in pairs, these unpaired varieties seek out other electrons so they can become a pair. When they pair up with electrons in our bodies it causes damage to cells, proteins, DNA, by stealing an electron. This process has been linked to various human diseases including cancer, atherosclerosis, neurological diseases such as Parkinson’s disease and premature aging. Although very similar and broadly referred to under the umbrella of antioxidants, essentially antiradicals are substances that can either act as an electron donor or an electron grabber whereas antioxidants are substances that can inhibit the process of oxidation. What is not similar is how each antioxidant and antiradical perform in different analytical assays or measurement testing. There are several well accepted measurement methods such as Hydrogen Atom Transfer methods (HAT) which include ORAC (oxygen radical absorbance capacity), TRAP (total radical trapping antioxidant parameter), and LPIC (Lipid peroxidation inhibition capacity) and Electron Transfer Methods (ET) which include FRAP (ferric ion reducing antioxidant parameter), TEAC (Trolox equivalent antioxidant capacity). There are other types of testing as well. What is interesting is that when testing foods for antioxidant capacity, it may perform well in an FRAP test, but it may not perform well under a TRAP test. Therefore, when an advertisement talks about a food or product being highest in antioxidants, it needs to be very specific about the type of assay it performed well in and we need to be discriminating in the interpretation of this data.
There are hundreds, probably thousands of different substances that can act as antioxidants and antiradicals. The most familiar ones are vitamin C, vitamin E, beta-carotene, minerals such as selenium, or substances that can’t be labeled so easily, such as Coenzyme Q10, glutathione, or quercetin. Substances such as polyphenols from grapes, isoflavonoids from soy, and carotenoids from certain vegetables, can act as antioxidants in their own way demonstrating unique chemical behaviors and biological properties that differ greatly from other antioxidants. There are different types of free radicals such as hydroxyl radical, peroxynitrite, lipid peroxyl free radical, singlet oxygen, hydrogen peroxide, so understanding that certain antioxidants and antiradicals match up or respond against one free radical but not another is where science is heading now.
The chart below shows different attributes to classify antioxidants. The first attribute is based on the function (primary antioxidants/antiradicals that react with lipid radicals and convert them into more stable products and secondary antioxidants that perform the function of capturing free radicals and stopping chain reactions). The second attribute is based on enzymatic (produced within the body) and non-enzymatic antioxidants (usually derived from the diet).