Antioxidants and Free Radicals in a nutshell:
Antioxidants are present in our bodies to help mop up “bad” free radicals that can do damage to cells, tissue, DNA etc. Free radicals are created in our bodies as chemical reactions take place, but not all free radicals are bad, just like not all antioxidants are beneficial.
What Is an Antioxidant?
An antioxidant is nothing more than a chemical that stops a process known as oxidation, which will be explained later in this article. Antioxidants are essential for human life, but supplemental antioxidants can be beneficial or detrimental to human health, depending on how much and when they are taken.
It's not especially helpful just to say that an antioxidant stops oxidation. Just a little bit of chemistry may be helpful if you haven't heard it all before.
The Chemistry of Oxidation
Oxidation is the process of giving up electrons to make a chemical bond. You have almost certainly seen the chemical formula for water, H2O. Although the term is almost never used, water could be called dihydrogen oxide (di = 2, so 2 hydrogens, and oxide = oxygen).
To form “dihydrogen oxide,” two hydrogen atoms each give up an electron to oxygen. Electrons have a negative charge. Giving up an electron raise the charge of the two hydrogen atoms together to +2.
Oxygen is capable of receiving two electrons. Receiving the two electrons from the two hydrogen atoms gives oxygen a charge of -2. When it comes to electrical charges, opposites attract. The two hydrogen atoms with the +2 charge “stick” to the one oxygen atom with the -2 charge and become dihydrogen oxide, better known as water. Hydrogen is oxidized to form water.
In the terminology of chemistry, oxidation doesn't always involve oxygen. You probably have also seen the chemical formula for table salt, NaCl. Table salt is also known as sodium (Na) chloride (Cl, in the form that is chemically combined to another element).
Electrons have a negative charge. Sodium gives up one electron when it forms table salt. Losing a negative charge gives sodium a positive charge of +1. The chlorine atom receives the electron and acquires a negative charge of -1. When sodium is oxidized it gets a positive charge. Transferring an electron with a negative charge reduces the total charge on chlorine so the two atoms can form a chemical bond. Whenever there is oxidation, there is always reduction.
Well, almost always.
The chemical reactions that occur in the human body are vastly more complicated than making water or salt. Dozens or even hundreds of steps in a chemical process may be needed to convert a molecule of sugar into carbon dioxide and water or to convert a mixture of amino acids into an enzyme. Many of these steps may be facilitated by enzymes that “catch” electrons so complex chemical products can be formed. And about once in 10,000,000 cycles (which is to say, millions of times every second in the body as a whole), something goes wrong so that an electron is stripped off a chemical in a cell without its being replaced.
Usually the problem is that an electron “leaks” from a chemical cycle. It might find a nearby oxygen molecule and transform it into a “superoxide” that can strip away positively charged components of other molecules. The resulting positively charged molecule can cause similar destruction by latching on to the negative components of still more nearby molecules.
The result is a series or positively and negatively charged free radicals. Free radicals can be regarded as “hungry” molecule that can strip electrons off chemicals that are involved in other metabolic cycles. It might destroy DNA, or protective lipids, or proteins that send signals inside the cells and to other parts of the body. It might “denature” a protein so that it no longer functions as part of the structure of the cell.
Cells make antioxidants to stop this kind of oxidation. The antioxidant stops destructive oxidation by being oxidized itself. Since it the antioxidant is not a part of the chemical reaction it protects, the normal operation of the cell is allowed to continue through the action of the antioxidant.
There are also antioxidants our bodies can absorb ready-made from food and supplements. The more we eat, the more our bodies burn sugar and fats and certain amino acids. The more we eat, the more proteins our bodies synthesize. The more we consume, the more antioxidants we need to keep the whole process going smoothly. But that doesn't mean that more and more and more antioxidants are necessary or beneficial for health. That's because free radicals aren't always bad.
Free Radicals Aren't Always Bad
While “stray” free radicals can be destructive to tissues in ways that cause disease and in ways that result from disease, free radicals can perform critical functions in the human body. Sometimes free radicals act as signals to initiate essential body processes.
A free radical of nitrogen and oxygen known as nitric oxide (NO), for example, signals the lining of arteries to relax. A free radical of iron signals cells in certain kinds of mucous membranes to reproduce themselves to repair tissues. Free radicals of oxygen trigger the process of inflammation, which removes foreign bodies, dead tissue, and injured tissue so it can be replaced with healthy tissue. Free radicals of oxygen also activate white blood cells to surround and consume disease-causing bacteria.
Free radicals methylate DNA, switching genes on and off so they can “remember where they have been.” This keeps mature cells from transforming back into stem cells, so they can perform the functions needed in the tissues where they are found. It helps genes express themselves at the right time in an individual's life. And free radicals make it possible for the body to link small molecules together to make larger molecules, such as using amino acids to make proteins and using the bases A, G, C, and T to make DNA.
Antioxidants Aren't Always Good
Obviously, when the body is using free radicals for a useful function, an excess of antioxidants is not a good thing. Some diabetics take so much of the antioxidant lipoic acid, for instance, that their bodies cannot use the trace minerals chromium, vanadium, and zinc—ironically causing deficiencies of enzymes that keep blood sugar levels in check. Some people take so much vitamin C that it begins to act as a pro-oxidant, vitamin C having sought out molecules to neutralize and, finding none, removing electrons from other molecules of vitamin C. These oxidized molecules of vitamin C then can damage neighboring molecules in the same way as the free radicals against which people take vitamin C to protect themselves.
Balance Is the Key
The key to using antioxidant supplements successfully is to take enough without taking too much. Generally speaking, you are likely to need to more antioxidants than your diet can provide if:
- You have diabetes. Large amounts of glucose in the bloodstream can begin to “auto-oxidize” even without being taken into cells. This process releases large number of free radicals. The free radicals activate white blood cells to attack cholesterol in the linings of blood vessels, increasing the risk of atherosclerosis.
- You have a condition called hemochromatosis. Hemochromatosis is a hereditary iron-storage disease. People who have hemochromatosis accumulate large amounts of iron in their bloodstream and in their tissues. This iron literally “rusts” tissues all over the body. Usually (although not always) hemochromatosis is simple for doctors to treat, but while the condition is being brought under control antioxidant supplements prevent the worst effects of the disease.
- You exercise a lot. Working out hard burns a lot of oxygen. Burning a lot of oxygen creates extra opportunities for the formation of free radicals. The exercise guru Dr. Kenneth Cooper was horrified when he realized that his patients who were the most dedicated to their daily workouts were also the most likely to die of cancer—until they started taking supplemental antioxidants.
- You live in an unusually toxic environment. If you live in Falkland Islands or Greenland or maybe if you live at a research station at the North Pole, you may be able to avoid toxic chemicals in your day to day environment. Most of the rest of us can't. Since our bodies use antioxidants to detoxify many different kinds of toxic free radicals caused by chemical pollution, most of us need additional antioxidants—in moderation—to compensate.
- You take a lot of just one antioxidant. In the 1990's, researchers in Finland were horrified to learn that their experiment in giving smokers supplemental beta-carotene resulted in increased rates of lung cancer. It turns out that antioxidants work as networks, and if you have a lot of just one part of the network, the class of antioxidants can't do its job.
So, if you are going to take antioxidants, which ones do you need?
The general rule is that you need all of the antioxidants in a network to do your body good. Here are the basics:
- If you take vitamin E, you need vitamin C.
When vitamin E neutralizes a free radical, it becomes a weak free radical itself. Vitamin C can recharge vitamin E so that it becomes an antioxidant again.
- If you take vitamin C or vitamin E, you need lipoic acid.
Lipoic acid can recharge both vitamin C and vitamin E, as well as the important antioxidant glutathione.
- If you take lipoic acid, you need to take the chemicals your body can use to make the antioxidant glutathione.
There are nutritional supplements that contain glutathione, but the glutathione they contain is very poorly absorbed by the body. It's best to take the “raw materials” the body needs to make its own glutathione, N-acetyl-cysteine and lipoic acid—but you don't have to take large amounts of either.
- If you take any of these antioxidants, you should also take coenzyme Q10 (Co-Q10).
CoQ10 helps vitamin E protect fats from oxidation. When these fats are in the lining of arteries, stopping oxidation stops the signal process that attracts the white blood cells that:
- feed on cholesterol to remove it from artery walls but
- get stuck in the lining of arteries and eventually become the “clog” that stops circulation (cholesterol is only part of the plaque that stops blood circulation.)
You need less CoQ10 to work as a co-factor for vitamin E, as little as 10 mg a day, than you need to give your heart protection from low oxygen levels, preferably at least 100 mg a day.
CoQ10 is expensive, so if you are on a budget, use it for prevention at the 10 mg a day dosage rather than using it for treatment at the 100 mg a day dosage.
- Flavonoid supplements tend to be less beneficial than they are advertised to be.
There are about 50,000 different antioxidant compounds in plants identified as flavonoids. This group contains the ginkgolides in Ginkgo biloba, the pycnogenol in pine bark, and the resveratrol in red wine (that is actually extracted from a plant known as knotweed for making resveratrol supplements). These plant compounds show great promise in laboratory experiments, but they usually don't get the results people expect when they are taken as supplements.
The basic reason flavonoid supplements don't work as well as expected is that the flavonoids that work well in the test tube tend not to be the ones that work best in the human body. The green tea antioxidant epigallocatechin gallate (EGCG), for instance, has real health benefits but in some of the most important chemicals cycles it is only 1/1500 as potent as the antioxidant kaempferol. Kaempferol is found in apples, grapes, strawberries, leeks, broccoli, green beans, and Brussels sprouts—but usually not on the supplements shelf.
The antioxidant quercetin, which is found in almost all vegetables and fruits but especially in grapefruit and apples, is up to 300 times more potent than resveratrol. But when was the last time you saw an Internet health site tell you to eat more apples before you take more supplements?
Vitamin C, vitamin E, lipoic acid in its various forms, n-acetyl-cysteine (NAC), and CoQ-10 are antioxidant supplements that will help almost anyone. Other antioxidants may be very helpful for specific health conditions. But eating 5 to 9 servings of fresh plant foods every day is essential for maintaining the nutritional balance that supports optimal health.