Oxygen is the third-most abundant element in the Solar System after Hydrogen and Helium. Oxygen makes up about 50% (by weight) of the Earth’s crust and about 20% (by volume) of the atmosphere.
Of course we all know that animals need oxygen for respiration. You can live for a month (maybe) without food. A few days without water. But mere minutes without oxygen.
Oxygen supports combustion. We’ve all blown on a flame to help it grow. Metabolism is not much different than combustion. We eat carbohydrates and they “burn” slowly in our gut, releasing energy and by-products like carbon dioxide.
In a pure oxygen environment a small spark could become a conflagration. Even the pipes and vessels used to contain gaseous or liquid oxygen could be consumed in a fire if one got started. It may be essential for life but it can also be a killer!
Oxygen is highly reactive and will combine readily with most things. Many of our important ores are oxides and they require a lot of energy to reduce them to base metals. Smelting iron ore into steel is the largest use of commercial oxygen. Added to the mix in the blast furnace it scrapes away carbon and sulfur impurities from the iron by forming, you guessed it, the oxides CO and SO2.
And then there’s that stuff we hear a lot about: antioxidants. We are supposed to eat blueberries by the sackful to prevent cancer and other maladies. What’s up with that?
Oxygen, in gaseous form, is diatomic. That is, two atoms combine to make an O2 molecule. This is the good stuff we need to live. Unfortunately once we get this molecule in our system it gets ripped apart and the individual oxygen atoms and ions form new combinations. The free radicals created cause serious damage to cells and tissues. What is necessary to life is also toxic.
Fortunately we have stuff like this:
That’s a model of Vitamin C, also known as ascorbic acid. This is a dietary antioxidant. The others are Vitamin A and Vitamin E. These help to inhibit oxidation and to clean up free radicals. Cells have their own antioxidants like glutathione and there are enzymes like superoxide dismutase (SOD) that are also antioxidants. Living things have systems for utilizing oxygen and for cleaning up the mess, too.
Antioxidant dietary supplements are worthless. It’s more important to eat well and be sure you get the necessary nutrients (like Vitamins A, C, and E!) from regular foods. A healthy metabolism also means that your body’s own scheme for coping with oxygen toxicity will function properly.
Many years ago I attended a lecture by a famous biochemist (Bruce Ames, inventor of the Ames Test). It was a fascinating and wide-ranging talk that covered nutrition, cancer, aging, toxicity and related topics. The audience was particularly interested in diet and in the Q-and-A afterwards one frustrated listener (it was a deep, information-dense event) asked the equivalent of “what does it all mean?” We were feeling a little overwhelmed and wanted to walk away with some straightforward, simple things we could do to stay healthy.
He told us to remember “what our mothers always said.” That is, “don’t smoke, don’t drink too much, cut down the sweets, and eat your vegetables.”
Sounds good to me!