How does the Body Tan?

Human being often expose their bodies to the sun to get a “tan”. Very few people realize that sunlight has many important effects on the skin. The most obvious is to produce redness or sunburn. This is caused by ultraviolet light.

It transforms “histidine”, a substance contained in the skin, into a substance that opens up (dilates) the blood vessels. And this is what causes the skin to become red. These is another substance in the skin called “tyrosine”.

Ultraviolet light transform this into the brown pigment called “melanin”. this melanin is then deposited in the outer layers of the skin to protect it against further action of the light rays and we call this effect “tanning”.


The sunlight also has a positive health effect. It destroys fungi and bacteria that may have settled on the skin. Sunlight also produces a substance in the skin which contracts the blood vessels. This result in raising the blood pressure.

Certain cells in the body which fight infection are stimulated to greater activity by the action of sunlight. Even the muscles of the body are “toned up”  by the action of sunlight. And the nervous system seems to be stimulated.

Also, the body obtains vitamin D because ultraviolet light performs a chemical change that produces it in the skin. In sunlight has all these good effects, shouldn’t a person get as much of it as possible?

The answer is that if sunlight acts like a medicine on the body, one should be careful about how much medicine to take. If you are out to get a tan, you should do it gradually ; a few minutes the first day, five more minutes the next day, and so on. Too much exposure to the sun may actually injure the skin an the body. 

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