The word “antioxidants” has been thrown around a lot in recent years as an increasing number of people have become more curious about the kind of food they should eat to help decrease the likelihood of multiple kinds of cancers and heart disease. Frequently, health articles reference antioxidants as one of the “good” things in food that people should consume more of. But what exactly are these mysterious substances, and what can they do for our health?
First, a brief chemistry lesson. Oxidation is the process by which a particular chemical substance loses electrons to another substance. Reduction is the process by which a particular chemical substance receives electrons from another substance. These two processes are frequently coupled in what is known as a “redox reaction” (reduction-oxidation).
These reactions are involved in multiple important processes in the human body such as cellular respiration in which sugar is converted to cellular energy.
Sometimes, redox reactions result in the formation of free radicals. Free radicals have an open electron shell, which makes them highly reactive. They play an important role in the human body because they help kill bacteria inside cells. However, if free radicals aren’t attached to another molecule, they can cause mutations within cells by reacting with DNA. They can also begin chain reactions, which cause cell damage. Some studies have shown that this damage can lead to cancer. This is where antioxidants come in. If an antioxidant is present, it will prevent the free radical from starting the chain reaction by reducing it (giving electrons to it) and thereby causing its own oxidation. Therefore, antioxidants must always be replenished in the human body through the ingestion of particular foods. It should be noted that besides being produced in the body, free radicals are also found in cigarette smoke. In fact, smokers take in 100 trillion free radical molecules each time they inhale smoke from a cigarette.
Now that we understand why antioxidants are important, the next question becomes what kinds of molecules are considered antioxidants, and where can we get some of these magical, wonderful substances?
Antioxidants can be grouped into two categories: those that are soluble in water and those that are soluble in lipids (fats). Some examples of water-soluble anti-oxidants include ascorbic acid (vitamin C), glutathione (which is synthesized by the body), and uric acid (the most abundant antioxidant in human blood). Lipid-soluble antioxidants include beta-carotene (the stuff that makes carrots orange), retinol (vitamin A), and α-Tocopherol (vitamin E).
Fun fact: Since Europeans mostly eat olive and sunflower oil, alpha-tocopherol is the most common form of vitamin E found in their diet. Since Americans eat mostly soybean and corn oil, gamma-tocopherol is the most common form of vitamin E found in our diet. The human body preferentially absorbs alpha-tocopherol. This is one of the reasons why the Mediterranean diet is so great.
Also, it’s interesting that selenium, which is way over on the right side of the periodic table, is often listed as an antioxidant, but it is actually not considered one. It actually assists antioxidant enzymes in their activity. It is found in tuna, Brazil nuts, and various grains.
As can be seen from the list of antioxidants, there is no mysterious berry or plant that one has to eat to increase the amount of antioxidants in their diet because they are actually found in a wide variety of foods. Vitamin C, a water-soluble antioxidant, is found in all kinds of fruits and vegetables including many varieties of berries, citrus fruits, guava, peppers, and mangoes. The list could go on for pages, but the most important thing to notice is that these fruits and vegetables naturally have a lot of color. It’s important to consume these foods either raw or steamed. Otherwise, there’s no point in eating them if all of the color and most importantly, the vitamin C, has been drained out of them due to over processing. Surprisingly, Vitamin C can also be found in things like beef liver and oysters. Since vitamin C is water soluble, the body does not store it and needs a “dose” of it everyday.
Vitamin E, a lipid-soluble antioxidant, is actually a general term for eight different kinds of compounds. It helps eliminate free radicals with the help of vitamin C. As stated before, when an antioxidant reduces a free radical, it becomes oxidized. In the case of vitamin E, it can then be reduced by vitamin C. Since vitamin E is lipid soluble, it is found in food that has a high percentage of “good” fat. Foods such as wheat germ oil, sunflower oil, avocados, and various kinds of nuts all contain this vitamin. Unlike vitamin C, the body can store vitamin E because it is lipid soluble. This means that only 15 mg of vitamin E need to be consumed by both men and women everyday. However, women need to consume 75 mg of vitamin C per day, and men need to consume 90 mg of vitamin C per day.
It seems that every time that scientists start praising a particular chemical substance or food for its health benefits, the public rushes to get as much of it as possible in any kind of form. This is not a wise action because all nutrients, including antioxidants, need to be consumed in moderation. Also, it’s better to consume these antioxidants in their natural forms instead of relying on supplements. You’ll have a much more pleasurable experience eating beautiful strawberries and juicy oranges than consuming synthetic products. The real stuff is always better.
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Wagner, Karl-Heinz; Afaf Kamal-Eldin, Ibrahim Elmadfa (2004). “Gamma-tocopherol–an underestimated vitamin?”. Annals of nutrition and metabolism 48 (3): 169–88.