The Chemical Composition of Human Sweat

As you might imagine, human perspiration is mainly water, but have you ever wondered just what else is in sweat? Here's a look at the process of sweating, the chemical composition of perspiration, and the factors that affect it.

Why Do People Sweat?

The main reason people perspire is that the evaporation of water can cool our bodies. That's the reason it makes sense that the main component of perspiration is water. However, perspiration also plays a role in the excretion of toxins and waste products. Sweat is chemically similar to plasma, but certain components are selectively retained or excreted.

General Composition of Perspiration

Perspiration consists of water, minerals, lactate, and urea. On average, the mineral composition is:

• Sodium (0.9 gram/liter)
• Potassium (0.2 g/l)
• Calcium (0.015 g/l)
• Magnesium (0.0013 g/l)

Trace metals that the body excretes in sweat include:

• Zinc (0.4 milligrams/liter)
• Copper (0.3–0.8 mg/l)
• Iron (1 mg/l)
• Chromium (0.1 mg/l)
• Nickel (0.05 mg/l)
• Lead (0.05 mg/l)

Variations in Perspiration Chemical Composition

The chemical composition of perspiration varies between individuals. It also depends on what individuals have been eating and drinking, the reason why they're sweating (for example, exercise or fever), how long they have been perspiring, as well as several other factors.

Sources

• Montain, S. J., et al. “Sweat mineral-element responses during 7 h of exercise-heat stress.” International, U.S. National Library of Medicine. International Journal of Sport Nutrition and Exercise Metabolism. December 17, 2007.