Q My sweat smells strongly of ammonia after a run. Is this normal?
A Don’t be too alarmed: the smell of ammonia in sweat is common among runners. Ammonia comes from the breakdown of amino acids (the building blocks of proteins) within the body. It is made up of nitrogen and hydrogen. The hydrogen atoms are converted to glucose and used as fuel. The nitrogen is a waste product that needs to be excreted by the body, and is processed in the kidneys to form urea that is excreted in urine. If there is too much nitrogen for your kidneys to deal with, it will be excreted as ammonia in your sweat.
One factor to consider is water intake. If you are consuming adequate fluid, the ammonia will be diluted – a decrease in the concentration will result in a less potent smell of ammonia. One way to be sure you are drinking enough fluids is to ensure your urine is clear.
Many people mistakenly believe ammonia sweat means that their protein intake is not high enough. The body will only utilise protein for energy when it does not have a sufficient supply of fats and carbohydrates. Muscles can use glucose and fat for energy, but the brain requires glucose. Since there is no direct metabolic pathway from fat to glucose when there is insufficient carbohydrate, your body will use amino acids. Therefore, if your sweat smells of ammonia don’t compensate by adding more protein (amino acids) to your diet, instead fuel your muscles and brain with what it prefers as an energy supply: carbohydrates. So, although protein is important in the diet, don’t go overboard. The recommended daily amount of protein is 15 per cent of your total calorie intake.
If you find the smell of ammonia persists try having a low glycaemic index carbohydrate, such as an apple, before your run and during prolonged exercise drink sports drinks to fuel your body and prevent amino acids being burned as energy. Don’t forget the body needs carbohydrate to burn fat so don’t think that providing some carbs before running is going to eliminate the fat burning process.
—Jane Newman, Sports Physiotherapist and Ultra Runner