Free Radicals and Antioxidants
A Deeper Dive
Ever wonder why a once shiny, new car gets bumpy rust spots over time? Or why that apple, banana, or avocado that you just cut, exposing its beautiful and delicious fleshy interior, begins to turn brown before you’ve even finished eating it? Perhaps you’ve learned that the trick for slowing down the browning process on many fruits is a small squeeze of fresh lemon juice? And that keeping the pit in the avocado will prevent browning?
If you’ve answered yes to any of these questions, then you’ve seen firsthand the effects of oxidation, and may have even prevented these effects through the use of antioxidants. Let’s take a closer look at what causes oxidation and similar types of chemical reactions. (We’ll give you a hint: oxygen is often a key player.)
The rust on your car or the brown on your fruit is due to the effects of reactive oxygen-containing molecules going through a process known as oxidation. Basically, oxygen or water from the air reacts with certain metals in your car, like iron, transforming it into rust, aka iron oxide. Similarly, certain molecules in the flesh of the fruit react with oxygen, ultimately yielding that unsightly brown hue.
Now, we all know that oxygen is indispensable for life—animals and humans alike. However, under certain conditions in living systems, reactive oxygen-containing molecules, called reactive oxygen species (ROS), can form, leading to damaging effects to proteins, DNA, and RNA, and can even result in cell death. These ROS are often highly reactive free radicals, specifically known as oxygen radicals.
Free radicals are a class of highly reactive atoms or molecules. They’re highly reactive because they have an odd number of electrons, which results in the existence of an unpaired electron. Atoms are satisfied and stable when electrons are in pairs, so these radicals roam the body seeking another electron with which to pair. In so doing, they can chemically react with and damage important molecules in our bodies, like DNA, proteins, fats, and sugars, which are necessary for a healthy life. These free radicals are thought to play a role in a range of diseases including cancer, cardiovascular diseases, diabetes, Alzheimer’s disease, Parkinson’s disease, and eye diseases such as cataracts and age-related macular degeneration, to name a few.
On a daily basis, we are exposed to potentially damaging free radicals from two primary sources: those that are produced naturally in our own bodies and those that come from our environment. Free radicals can be produced naturally in our bodies during metabolism, although their levels within our bodies are generally low. However, they can increase due to a number of factors, including inflammation, cigarette smoke, excessive exercise, environmental pollutants, radiation including UV sunlight, and even by conversion of food into energy within our cells. These factors can cause molecules to split into single atoms or smaller molecules with at least one unpaired electron, which are highly reactive and scavenge the body for another molecule’s electron for pairing.
Just like molecules, atoms are also made of smaller parts. Atoms consist of a nucleus, made up of protons and neutrons, as well as an electron cloud, which orbits around the core of the atom. To visualize this, imagine this looking something like a microscopic version of our solar system, with the planets, representing the electrons, orbiting around the sun. In this case, the sun would be the nucleus, or center of the atom.
However, unlike the planets in our solar system, electrons typically orbit the nucleus as a wave, rather than a particle, and they also prefer to be in pairs. A lone oxygen atom for instance, has eight electrons, with two of them being unpaired. Therefore, an oxygen atom is typically found, and most stable, with two bonds: either as two separate single bonds or as one double bond. In each bond, the oxygen atom is borrowing an electron from another atom to satisfy its need to pair each of its lone, unpaired electrons. Other atoms have a different number of electrons and may be most stable with a different number of bonds to it. Sometimes this electron pairing within a molecule can become disrupted, thus creating a lone atom or molecule that contains an unpaired electron.
The unpaired electron alters the atom’s or molecule’s stability, thus making it much more reactive. In order to become stable again, the atom needs to, essentially, borrow an electron from another atom in its vicinity. This borrowing leads to chemical reactions, some of which are damaging when they occur within our bodies.
In other words, atoms or molecules with unpaired electrons need to borrow or share an electron from another atom in order to attain their own peaceful state of zen. The atoms from which the electrons are borrowed are changed due to this reaction. In some cases, these reactions damage or destroy the interacting molecules—not good outcomes for the building blocks of our bodies!
Fortunately for us, under normal conditions, the potentially damaging effects of these free radicals and their electron-borrowing properties are kept in check within our bodies by another class of molecules: antioxidants.
Antioxidants are molecules that neutralize the reactivity of free radicals by lending them an electron to make them stable again. Hence, the levels of free radicals are lowered in the presence of antioxidants, thus preventing damage to other molecules that are important for the normal functioning of our bodies. Because of the activity of antioxidants in our bodies, they are potentially important in the prevention of cancer, aging, and a variety of other diseases.
Vegetables, fruits, nuts, and whole grains are rich sources of antioxidants, and hence many, such as vitamins C, E, A, and related carotenoids, selenium, and a variety of phytochemicals such as lycopene, lutein, and quercetin, come from our diets. The fact that squeezing fresh lemon juice that is high in vitamin C over freshly cut fruit to slow the browning process highlights its antioxidant activity. Antioxidants like vitamin C provide similar protections within our own bodies—this is why citrus is such an important part of our diet. To this end, there is strong evidence that eating a diet rich in vegetables and fruits is healthy, and official U.S. government policy urges all of us to eat more of these antioxidant-rich foods. Importantly, even in the absence of dietary antioxidants, our own bodies produce one of the strongest antioxidants ever discovered: glutathione.
Antioxidants, whether they come from our diets or are synthesized naturally by our own bodies, are an essential part of the body’s defense system. One such antioxidant, glutathione, has been called the Master Antioxidant or the Mother of All Antioxidants. This is due to several key factors, including the following:
- Almost all living things on Earth need glutathione.
- Glutathione is found within almost every cell.
- Glutathione plays a key role in naturally maintaining a safe, low level of free radicals.
- Glutathione can reactivate other antioxidants, like vitamins C and E, to their active forms. (Essentially, after either acts as an antioxidant by donating an electron to a free radical, glutathione can replenish that electron, thus restoring another round of antioxidant activity.)
- Glutathione can reactivate itself.
- This combination of critical features in a single antioxidant is distinctive to glutathione.
There are virtually no living organisms on this planet—animal or plant—whose cells don’t contain some glutathione. Hence, scientists have speculated that glutathione was essential to the very development of life on earth. That all sounds pretty important, don’t you think?
Cellular glutathione levels can be depleted by such things as environmental pollutants (tobacco smoke, fuel exhaust, chlorine to treat water, etc.), drugs (acetaminophen, alcohol, etc.), X-rays, UV radiation, aging, infection, trauma, and lifestyle (poor diet, stress, excessive exercise, etc.). Given its functions, it is essential to prevent glutathione levels from becoming too low.
Disease can also affect glutathione levels. People who are severely ill, with diseases such as cancer or AIDS, almost invariably have reduced glutathione levels, potentially highlighting the importance of glutathione for maintaining good health. In fact, research shows that increasing cellular levels of glutathione can raise energy levels, strengthen the immune system, fight inflammation, improve athletic performance, detoxify the body, aid in cellular repair, and slow down the aging process. Due to these benefits, glutathione is currently used clinically to prevent oxygen toxicity during hyperbaric oxygen therapy, treat heavy metal poisoning, lower the toxicity of chemotherapy and radiation in cancer treatments, and for reversal of cataracts.
Who could deny the importance of the Master Antioxidant?