As the refreshing spring gives way to the humid rainy season and then summer, the season arrives when concerns about body odor become more prominent. How do you all manage your sweat? No matter how much we try to suppress it, we cannot stop sweating. So, this time, we asked for tips on how to coexist with sweat and spend the summer comfortably.

Q. Please explain the mechanism of sweating.

First, there are several types of glands on the skin's surface. The most common are the "sebaceous glands," located deep within the pores, which secrete sebum, and the "sweat glands," which release moisture onto the skin's surface. Sweat is secreted from these sweat glands. So, when do we sweat? Primarily when it's hot. "Sweat glands" play a role in thermoregulation; by sweating and allowing the sweat to evaporate, we cool our bodies. As a side note, dogs and cats do not have sweat glands. When they pant heavily on a hot summer day, it's their way of regulating body temperature through respiration.

Q. I see. So, are there different types of sweat?

There are two types, secreted from "eccrine sweat glands" and "apocrine sweat glands." "Eccrine sweat" is mostly water, with small amounts of salt, sodium lactate, and urea. The reason sweat tastes salty is due to the salt content. Sodium lactate, on the other hand, is a natural moisturizing factor found in the skin. It can be said that the reason our skin doesn't dry out easily during the sweaty summer is because sodium lactate provides moisture. While this might seem beneficial for preventing dry skin, we can't ignore the odor caused by ammonia. One of the causes of "body odor" is the smell of ammonia, which is produced when urea is broken down by bacteria.

Q. What kind of sweat is secreted from "apocrine sweat glands"?

While the odor from "eccrine sweat" is caused by bacterial decomposition, sweat secreted from "apocrine sweat glands" is often thick and malodorous. For example, body odor (bromhidrosis) is common in individuals whose apocrine secretions have a strong smell. This varies by individual due to genetics, but it is particularly prevalent in people of Western descent. This is also referred to as pheromonal scent, and like animals such as the "musk deer" that produce strong odors, it is thought to be a remnant of a time when scent was used to indicate one's presence or attract mates.

Vol. 15: Mastering the Art of Summer Sweat

Q. When is sweat secreted from apocrine sweat glands?

There are tube-like structures called apocrine glands beneath the skin. When the cells within these glands mature, they release secretions containing cytoplasm, which is what constitutes apocrine secretion. Therefore, it's not triggered by a specific event but rather seeps out gradually as the secretions mature.

Q. Do the number and activity of sweat glands differ by body part?

Yes, they do. For instance, "eccrine sweat glands" are primarily for thermoregulation, so they are abundant in areas where sweat can easily evaporate, such as the forehead and back. In contrast, "apocrine sweat glands" are mainly found in limited areas like the armpits and groin. In moist areas like the armpits, there are many bacteria, and these bacteria can break down sweat, further intensifying the odor.

Q. I see. So, deodorant products are developed specifically to address sweat secreted from "apocrine sweat glands," aren't they?

That's correct. The key is to suppress the odor from apocrine sweat glands. Deodorant products contain antibacterial agents aimed at preventing the breakdown of proteins and urea by bacteria, as well as ingredients that help constrict the sweat ducts.

Q. Is there any adverse effect on the body from blocking the sweat ducts?

Basically, no. It only temporarily constricts the pores that secrete sweat, making it less likely to come out, but it will eventually be released. As I mentioned earlier, most odor is caused by bacteria, so the main focus is on preventing the secreted sweat from becoming malodorous due to bacterial activity. However, for summer sweat care, it's most important not to rely solely on deodorant products, but to wash it off within the day and maintain cleanliness.

Q. Finally, please share your tips for managing summer sweat effectively.

The key is to facilitate the body's thermoregulation, which is the role of sweat. For example, choose clothing that allows sweat to evaporate easily. Also, shaving underarm hair can be effective in reducing bacterial growth. Sweating is essential for survival, so we cannot stop it. Accepting this fact and learning to coexist with sweat is the quickest way to enjoy a comfortable summer.


Miyoharu Okabe Official Website
The Science of Beauty: "Garden of Beauty Science"
http://www.kt.rim.or.jp/~miyoharu/