CAUTION: Breathing Can Be TOXIC!!
Oxygen is potentially toxic, a seemingly counterintuitive statement, since common knowledge tells us that we need oxygen to live. Specifically, without oxygen we would not be able to produce energy from basic nutrients and would die….
So, how can oxygen be toxic?
Oxygen is an Electron Sponge
Nothing is perfect. The exact same property that makes oxygen a benefit to the cell, makes it a danger to the cell, its ability to absorb electrons.
Oxygen: The Benefit
The removal of electrons by oxygen is an essential step in the “oxidation/combustion” of foods. In biochemical terms a nutrient is nothing more than a collection of Carbon-Hydrogen bonds that can be broken to release electrons - electrons, in turn, are energy. During cellular respiration the cell uses these freed electrons to create its own energy molecule, a molecule called ATP (Adenosine TriPhosphate).
Take a look at the molecular structure of ATP here:
Unaccompanied Electrons Are Also Dangerous…
Once the electrons have been used to create ATP they need to be discarded from the cell. Otherwise they would raise havoc by interacting with unsuspecting cellular components. This is where oxygen comes in; in the best of conditions, oxygen removes these electrons from the cell as soon as they are freed and in the process forms water.
Oxygen: The Danger
What transforms oxygen from a cellular benefit to a detriment is a reduction in the efficiency with which it absorbs electrons. Oxygen becomes “reactive” when it is unable to absorb its full capacity of electrons and is left half satisfied, figuratively speaking. Sloppy electron absorbance is most common when the rate of oxygen utilization increases dramatically.
Under what circumstances would we need to increase our rate of oxygen utilization?
Exercise increases the need to break down nutrients to produce enough energy to maintain strenuous physical activity. The greater the rate of nutrient combustion, the greater the use of oxygen, the sloppier the process of electron transfer becomes and unfortunately, the greater number of Reactive Oxygen Species, or ROS, that are produced. ROS are also a form of “free radical”.
Fortunately, the body has come up with ways to combat ROS production. The body’s ROS defense mechanisms include a battalion of molecules known as antioxidants, whose job is to molecularly stabilize ROS (by converting them back into oxygen and water) immediately upon their production.
The body produces it own antioxidants from proteins such as Superoxide dismutase, Catalase and Glutathione as well as obtains them from the diet in the form of vitamins A, C and E. When the rate of nutrient combustion (oxidation) increases dramatically, however, the body’s oxidative defense mechanisms cannot keep up and ROS damage occurs. This has led to many athletes taking antioxidant vitamins to defend against free radical damage and potentially, over training syndrome.
Do Antioxidant Vitamins Actually Reduce Free Radical Damage During Exercise?
Next time I’ll discuss a study that examined the ability of vitamin antioxidants (taken in capsular form) to combat oxidative stress (ROS neutralization) during exercise. The results of this study were rather surprising and relevant to anyone taking vitamins A, E, or C to combat oxidative stress during exercise.
In brief, the study suggests that antioxidant supplementation does not improve our ability to defend against free radical damage during exercise. Don’t despair, however, there is still room for an alternative interpretation of these results.
Until next time…