What is the chemical composition of human sweat?

There are two types of sweat, depending on the sweat glands that produce it. The eccrine glands are distributed throughout the body surface, although they are concentrated mainly on the palms of the hands, the soles of the feet, the forehead, the face and the chest. Eccrine perspiration is made up of water, acids, urea, and minerals.

The second type of sweat comes from the apocrine glands . In addition to the components mentioned above, the sweat they produce also contains organic material, such as cell fragments, fats, nitrogenous bases, amino acids, and other substances. Apocrine glands are located in the armpits, mammary areolas, ear canals, and genitalia.

Commonly, sweat is made up of 95% water and other substances that favor the natural hydration of the skin, and urocanic acid, a natural filter that protects us from solar radiation. In general, sweat contains the following minerals: potassium, sodium, chlorine, phosphorus, calcium, magnesium; amino acids, proteins, lipids, lactic acid and urea, as well as zinc, copper, iron, chromium, nickel, and lead, among others.

If a sample of 10 g sweat is taken and analyzed, its chemical composition is usually approximately:

• 0.34-1.6 g of nitrogen compounds (derived from nitrogen).
• 0.04-0.1 g of calcium salts.
• 0.3-0.5 g of potassium salts.
• 2-5 g of sodium chloride.
• 2-5 g of lactic acid.
• 5.1-9.0 g of water.

However, the composition of a person’s perspiration can vary according to different factors, such as diet, drink, exercise, fever, the existence of a disease, the use of medicines, and others.

myths about sweat

There are some myths regarding sweat. The most common are:

• The smell of sweat: It is common knowledge that sweat has a bad smell. However, sweat itself does not smell. In most cases, the bad smell that we feel when we sweat is due to the batteries that are present in the body and interact with the substances in the sweat. When it reaches the epidermis, the bacteria break down some of its components, causing a bad smell. At other times, mainly in adolescence, hormonal changes also influence the smell of sweat.
• Sweat and Weight Loss: Many people believe that sweating more equals more weight loss. This is not entirely true, since although performing physical activities in which we sweat does help to lose weight, sweating by itself does not eliminate accumulated fat. Although after a sweaty training session you may notice a slight decrease in weight, this is simply a matter of eliminating fluids through perspiration.
• Can sweat be avoided?: Although it is usually somewhat annoying, sweat is vital for bodily functioning and cannot and should not be avoided. However, it can be controlled with the use of antiperspirant products, which block its production in certain areas of the skin. Also, other cosmetic products such as deodorants can be used, which eliminate or disguise the smell of perspiration.

Bibliography

• Barria, K.; Carreno, N.; Tieppo, L. Hyperhidrosis: Assessment, Quantification, and Treatment with Iontophoresis . (2012). Spain. Spanish academic publisher.
• Teja Angulo, J. Living without sweat: A guide to overcome hyperhidrosis . (2020). Spain. kindle edition.