In the process of chemical reactions, highly reactive chemical substances, collectively called reactive oxygen species, are produced.

Currently, the following four types of oxygen are known to exist.

Superoxide
Hydroxyl radicals
Hydrogen peroxide
singlet oxygen

Of these reactive oxygen species, superoxide and hydroxyl radicals are substances that have "unpaired electrons". Substances with unpaired electrons are scientifically very unstable and have the ability to take electrons from surrounding substances, i.e., they are very strong oxidizers. Substances with unpaired electrons are sometimes called "free radicals". (Hydrogen peroxide and singlet oxygen are not free radicals).

Oxidative stress refers to damage to the body caused by highly chemically reactive substances, such as reactive oxygen species, including "free radicals".

In the case of humans and other mammals, the majority of oxidative stress is thought to be caused by hydroxyl radicals, which readily associate with all kinds of substances such as proteins, fats, and carbohydrates to accumulate damage to the body.

Although reactive oxygen species (ROS) are now seen as complete "bad guys" for rusting the body, in fact, our bodies are equipped with systems to generate ROS and use them effectively.

A representative example is the white blood cells that act as the body's defense force. After activating oxygen, the white blood cells convert it into hydrogen peroxide. From there, they produce "hypochlorous acid" and "hydrogen peroxide".

Hypochlorous acid and hydrogen peroxide, you all know it, don't you? Yes! They are disinfectants and chlorine bleach used in laundry.

These two substances are highly reactive and easily produce hydroxyl radicals. Their oxidizing power is so strong that they can oxidize, or rust, bacteria and viruses at once.

That is why they are used for disinfection and prevention of norovirus. These "highly oxidizing substances" are produced in the body.

However, the biological body is very well designed.

Even though hydroxyl radicals are produced, the body also has an "antioxidant system" to eliminate their harmful effects. As long as there is a balance between the oxidizing effect and the body's own antioxidant system, it is not a big problem.

However, we are surrounded by factors that increase the production of reactive oxygen species, such as ultraviolet rays, smoking, and automobile exhaust. Whether it is mental or physical stress, consuming large amounts of alcohol, or eating too much sugar, the amount of reactive oxygen species increases.

Lack of sleep due to a busy work schedule, binge drinking, binge eating... These kinds of stresses can overwhelm the processing capacity of our body's antioxidant system.

Then, the bad side of reactive oxygen species will come out, and the body will be exposed to oxidative stress. This is not a good thing, as it can accelerate aging and increase the risk of various diseases. We should try to live a life that reduces the effects of oxidative stress as much as possible.