By Elena Voropay

You find it everywhere. You do everything possible to get rid of it but it keeps coming back. It may be the most disturbing and isolating factor during a training session and the famous smell of the gym locker-rooms. It is the bad old sticky, smelly, yucky, dripping sweat. There is nothing pleasant about its presence, but sweat has a very important mission to complete - keep you healthy, that is. Researchers have found that sweat contains a natural antibiotic that may keep our natural skin-dwelling bugs in check.

The protein Dermcidin found in sweat clears the skin of disease causing bacteria such as E. coli, Staphylococus aureus and yeast Candidia albicans. Sweat glands constantly secrete the antibiotic but excessive washing could remove our natural germicide. Since bacteria thrive in warm, moist conditions, antimicrobials are vital to stop dangerous micro-organisms from attacking the body. According to Tomas Ganz who studies such 'antimicrobial peptides' at the University of California in Los Angeles, by limiting what lives on the skin, the protein may be "our first line of defence." Natural antibiotics in sweat may be especially important when the skin is damaged stopping resident bacteria getting inside to cause infection. But it doesn’t really matter how much you sweat, it depends on how much Dermcidin is released in sweat.But how Dermcidin disables bacteria is a mystery considering the fact that it behaves differently from other peptites.

Antimicrobial peptides can be found on all surfaces of the body that meet the outside - such as intestines, mouth and lungs. Bacteria and peptides fight a constant battle, one evolving rapidly to cause infections, the other to thwart them. There two known classes of small skin proteins that are secreted in response to infection and inflammation and can successfully fight bacteria.

The first class is called "cathelicidins" found in wound fluid. They get released at sites of inflammation in diseases such as systemic lupus erythematosis, psoriasis and nickel contact dermatitis. The other main class of antibacterial proteins is "defensins". The alpha-defensins are made inside white blood cells or inside cells in the small intestine. But there's a whole group that are found only on the skin - beta-defensins. The big difference between Dermcidin and the other antibacterial skin chemicals is that it's produced whenever you sweat - not when you've got inflammation.

So while frequent showers may be good for keeping friends, medicated deodorants and skin-washes which kill bugs could upset the skin's bacterial balance.

Why Do We Sweat

Heat

We might not notice it, but we sweat all the time. And sweat doesn't come from two or three places, but from more than 2.6 million small sweat channels, known as sweat glands. Sweat is our special device to reduce body temperature when it goes above normal. In other words, we perspire to maintain the temperature of our internal thermostat set to an average of 98.6 degrees Fahrenheit, or 38 degrees Celcius. A single degree C rise in temperature can raise heart rate by about 10 beats per minute! To prevent internal overheating, our bodies come fully equipped with a temperature center in the brain, which consists of a control center, a heating center, and a cooling center.

Burning approximately 2,500 calories a day to fuel all functions of the body, we produce enough heat to bring 25 quarts of water to the boiling point. Exercise generates even more heat. But only about 25 percent of the energy in a workout might be needed for the action of moving, throwing a ball, activating muscles, etc. The other 75 percent is leftover heat.This causes the temperature of the blood to rise thus calling the cooling center into action. The brain's cooling center slows the heating process, and opens the glands in the skin to release the excess heat and the fluid known as perspiration. A pea-sized bead of sweat can cool nearly 1 liter (about 1 quart) of blood 1-degree F.

Hormones

The amount of sweat produced depends upon our states of emotion, physical activity, and hormone levels. For women, sex hormones progesterone and oestrogen are key players in regulating body temperature. Progesterone nudges the temperature up and oestrogen brings it down. Exercising women with higher oestrogen levels will become red-faced and sweaty earlier.

How sex hormones alter women's temperature regulation is yet to be determined, but researchers believe the hormones bind to specific brain neurons affecting temperature regulation. Oestrogen dominance may be caused by a variety of factors, including oral contraceptives, early onset of puberty, or even petrochemical products such as plastics, which have shown to release oestrogen in test tubes. Naturopaths think that one of leading causes of oestrogen dominance is consuming foods and drinks from plastic containers.

Usually normal amounts of sweat can be made in response to nerve stimulation, hot air temperature, and/or exercise. If you are sweating excessively, then you might need to look at underlying causes such as low blood sugar, liver or kidney disease, diabetes, parasites, metabolic dysfunction, menopause, or prolonged extreme emotional stress.

Other Factors

High temperatures cause you to sweat more quickly and to lose more fluids through sweat. Humidity also reduces your ability to cool off and slows down sweat evaporation. Minimal, loose-fitting clothing helps promote heat loss. Genetics play a small role in your capacity to sweat. Regular physical activity and increased fitness level will help your body to adapt to exercise in warmer temperatures by sweating more thus better maintaining a healthy homeostasis of your internal environment.

Smelly or not, sweat cleanses the body, maintains the temperature, and preserves immunity.

References:

1. Schittek, B. et al. Dermcidin: a novel human antibiotic peptide secreted by sweat glands. Nature Immunology, advance online publication DOI: 10.1038/ni732 (2001).

2. Stachenfeld, N. S., Silva, C. & Keefe, D. L. Oestrogen modifies the temperature effects of progesterone. Journal of Applied Physiology 88, 1643 - 1649 (2000).

3. Preti, G. et al. Male axillary extracts contain pheromones that affect pulsatile secretion of luteinizing hormone and mood in women recipients. Biology of Reproduction, 68, 2107 - 2103, (2003).