Topic 2: Reduction, Oxidation, Free Radicals and Antioxidants

Have you ever wondered, just what the heck are "free radicals" or what are "antioxidants"? How does it affect me? If I take vitamins does that mean I am "safe"? This article is to discuss just this and to gain some practical understanding. Some of this is gonna get pretty "sciency" so bear with me and post any questions you have, and I will try my best to answer them. Here we go!

"Chemically, oxidation is defined as the removal of electrons and reduction as the gain of electrons. Thus, oxidation is always accompanied by reduction of an electron acceptor. " Harper's Illustrated Biochemistry, 29e: Chapter 12. Biologic Oxidation

Free radicals are highly reactive molecular species with an unpaired electron; they persist for only a very short time (of the order of 10–9 to 10–12 sec) before they collide with another molecule and either abstract or donate an electron in order to achieve stability. Harper's Illustrated Biochemistry, 29e: Chapter 45. Free Radicals and Antioxidant Nutrients

Free radicals are formed in the body under normal conditions. They cause damage to nucleic acids (DNA/RNA), proteins, and lipids in cell membranes and plasma lipoproteins (proteins that are soluble in blood that carry fats). This can cause cancer, atherosclerosis and coronary artery disease, and autoimmune diseases. Harper's Illustrated Biochemistry, 29e: Chapter 45. Free Radicals and Antioxidant Nutrients

The most damaging radicals in biological systems are oxygen radicals (sometimes called reactive oxygen species or ROS). Tissue damage caused by oxygen radicals is often called oxidative damage, and factors that protect against oxygen radical damage are known as antioxidants. Harper's Illustrated Biochemistry, 29e: Chapter 45. Free Radicals and Antioxidant Nutrients

Epidemiological and laboratory studies have identified a number of protective antioxidant nutrients: selenium, vitamins C and E, β-carotene, and other carotenoids, and a variety of polyphenolic compounds derived from plant foods. Harper's Illustrated Biochemistry, 29e: Chapter 45. Free Radicals and Antioxidant Nutrients

The peroxides that are formed by radical damage to lipids in membranes and plasma lipoproteins are reduced to hydroxy fatty acids by glutathione peroxidase, a selenium-dependent enzyme (hence the importance of adequate selenium intake to maximize antioxidant activity), and the oxidized glutathione is reduced by NADPH-dependent glutathione reductase. Lipid peroxides are also reduced to fatty acids by reaction with vitamin E, forming the relatively stable tocopheroxyl radical, which persist long enough to undergo reduction back to tocopherol by reaction with vitamin C at the surface of the cell or lipoprotein. The resultant monodehydroascorbate radical then undergoes enzymic reduction back to ascorbate or a nonenzymic reaction of 2 mol of monodehydroascorbate to yield 1 mol each of ascorbate and dehydroascorbate.

Ascorbate, uric acid and a variety of polyphenols derived from plant foods act as water-soluble radical trapping antioxidants, forming relatively stable radicals that persist long enough to undergo reaction to nonradical products. Ubiquinone and carotenes similarly act as lipid-soluble radical-trapping antioxidants in membranes and plasma lipoproteins. Harper's Illustrated Biochemistry, 29e: Chapter 45. Free Radicals and Antioxidant Nutrients

Ok, lets recap. Free radicals are formed under normal cellular conditions. They are also formed by various environmental influences such as toxins found in our air, water, and food, from inflammation, and exposure to ionizing radiation. These free radicals, once formed, cause damage to our normal cellular structures that are crucial for keeping us healthy and functional.

Our defense to these free radicals are called antioxidants. Some of these antioxidants our bodies can make on its own such as Glutathione (GSH) and Superoxide Dismutase (SOD), when given the right nutritional building blocks. However, many antioxidants are found in the foods we eat, specifically plant foods. So how do you recognize foods with lots of antioxidants? COLOR. Antioxidants are pigments of color.

The way the level of antioxidants are measured is called the ORAC scale, or the Oxygen Radical Absorbance Capacity. The higher the number, the more powerful/numerous the antioxidants in a specific food.

So more is better right? Well we without a doubt need a variety of different antioxidants to battle the normal cellular free radical formation, but because we are bombarded with supra-physiologic levels of environmental toxins, more may be better, but the published data is confusing.

The reason being, some research was done looking at groups of people with low levels of common diseases such as cancer and heart disease. They measured levels of antioxidants, and they found they had higher levels of certain antioxidants. So they made the conclusions that antioxidants prevented cancers and heart disease, and we must recommend everyone take large doses of antioxidant supplements.

Well, when they studied people who took vitamin supplements for a period of time, they found that there were little or no differences in rates of cancer and heart disease, but in some, there were increased rates! Yikes! So what can we make of this?

I think two questions need to be asked. We have to wonder what were these people (diet) who had low levels of cancer and heart disease and high levels of antioxidants doing? Was it the fact that these people were taking synthetically created vitamins a reason for failure in the study?

We can only speculate of course. My personal opinion is that the antioxidants were markers of good health, not the one solution to a complex problem. Likely these people had high antioxidants because they were eating a variety of high nutrient dense, colorful plant foods that contained high levels of antioxidants which could be measured. Second, the fact that these vitamins were isolated, mega-dosed, and synthetic has to be taken into consideration.

I think the take home message of this article and future articles is that a good variety of fresh, whole, ripe, unprocessed, and organic if possible PLANT FOODS are the most important thing you can be putting in your body. That being said, if you decide to supplement, try to get a whole food/natural state/full spectrum supplement.

VS

For example, lets say you want to supplement with Vitamin E. Great. Ditch the 400 I.U. of d-alpha tocopherol bottle for a supplement with mixed tocopherols and tocotrienols. When in doubt, look at the label as above.

To your health,

Dr. Peavler