Electrolytes: small in size but important

Lait au chocolat

Published on 20 March 2015
by Mélanie Olivier

Hot weather is back, and thus, so is sweat! Whether you are into extreme moving, a golfer or a cyclist, sweat is part of your hot summer days. And since we are addressing sweat, you certainly have heard of ELECTROLYTES before, as in sports drink? What are electrolytes? Who can benefit from them? Why are they important?

What is an electrolyte?

Electrolytes are chemical elements that, once incorporated into water, allow electrical current to circulate within our body; it is said that they ionize in water. Their balance is important to ensure good functioning of cells, maintenance of pH and transmission of nervous influxes throughout bodily fluids and tissues. Among the most common electrolytes, you can find sodium, magnesium, potassium, and calcium. When one sweats, sodium is the electrolyte that is most lost. The loss in potassium and calcium are less important; the loss in magnesium are rather unimportant.       

Sodium and potassium

We normally hear most about sodium and potassium as both play an important role in muscle contraction and nervous transmission, and contribute to maintaining balance in bodily fluids. A diet poor in salt helps maintain that balance; the more important the salt intake, the more our body will need it to maintain that balance, the more sweat will contain high sodium concentration.  If you find salt residues on your t-shirts, racing shorts, or caps and that you sweat a lot, it becomes important to compensate the loss in sodium if the activity lasts more than 90 minutes. Remember that 1 g of salt contains 388 mg of sodium – the remainder is chloride. A pinch of salt thus contains quite a lot of sodium.

Potassium is not to be neglected, but since it hides inside cells, its concentration is of lesser importance in sweat. It is important to highlight that many Canadians do not fulfill their need in potassium. It appears that a diet including little vegetables and fruits would be to blame for that deficit. You can rest assured, if you eat a variety of fruits and vegetable – such as bananas, oranges, potatoes and almonds, and if you drink vegetable cocktails and milk– on a daily basis.   

Calcium and magnesium

Often associated with bone health, they also play a role in muscle contraction and relaxation. Even though the concentration of calcium and magnesium remains low in the composition of sweat, these two minerals remain important where physical activity is concerned and must be an integral part of one’s diet. This is why they are part of electrolytes lozenges and of sports drink high in electrolytes.   

Electrolytes supplement: necessary or not?

If you practice a high intensity sport for more than 90 minutes, that you sweat abundantly, or that you are leaving for 30 to 60 minutes when it’s hot and humid outside, it becomes important to add 300 to 500 mg of sodium per litre of water.  People that sweat a lot, should add up to 700 mg per litre.

Apart from drinking sports drink, it is possible to satisfy your needs in electrolytes thanks to a varied diet.

For example, here are the quantities of electrolytes contained in 250 ml (1 cup) of 1% fat chocolate milk, and that you could drink during recovery period after making an effort:

Sodium: 161 mg
Potassium: 449 mg
Calcium: 304 mg
Magnesium: 34 mg

Mélanie Olivier
Dt.P. M.Sc., sport nutritionist/dietitian and president of VIVAI: experts in nutrition