Electrolytes
Also called: sports drink, electrolyte tablets, hydration powder, oral rehydration salts, sodium, potassium, magnesium.
Sodium, potassium and magnesium sold for hydration; useful when you sweat for a long time or in the heat, otherwise mostly sugar or flavoured salt.
What it is
Electrolytes are the dissolved minerals that regulate the body's water and nerve conduction: sodium, chloride, potassium, magnesium, calcium. Sweat loses mostly sodium, at a concentration that varies widely from one person to another, and very little potassium. People buy them for training, heat, cramps and, increasingly, as an everyday drink.
What the label does not say
- Sodium is the electrolyte that counts, and it is often the least present: sweat contains 10 to 70 mmol/L of it (about 230 to 1,600 mg per litre), at rates of 0.5 to 2 L per hour, versus 2 to 8 mmol/L of potassium (Baker 2017). A product that showcases magnesium, potassium and "five electrolytes" with little sodium does not replace what is going out.
- When it is useful and when it is sugar: the AIS places the value of sodium in efforts of more than one hour with heavy sweat losses, ultra-endurance, heat and rehydration after a large deficit, writes that no consensus exists on the value of replacing sodium during exercise, and considers sports drinks unnecessary under 45 minutes. At 6 to 8 g of sugar per 100 mL, a 600 mL bottle brings 36 to 48 g; Health Canada allows the carbohydrate performance claim only beyond 60 minutes of intense exercise.
- Hyponatremia in endurance athletes comes from excess water, not lack of salt: the 2015 international consensus attributes all known deaths to overconsumption of hypotonic fluids, specifies that all sports drinks are hypotonic (10 to 38 mmol/L of sodium) and do not protect against dilution when you drink too much, and recommends drinking to thirst. Symptomless hyponatremia affects up to 13% of marathon finishers and up to 51% in 161 km ultramarathons.
- Potassium in supplements is capped: Health Canada limits the potassium in natural health products to 200 mg per day ("electrolyte" use from 100 to 200 mg), with the statement "do not use with other potassium-containing supplements or salt substitutes", and the NIH reports that in the United States most manufacturers stop at 99 mg per serving because of small-intestine lesions linked to potassium chloride. Against an adequate intake of 3,400 mg (men) and 2,600 mg (women) per day, a packet changes just about nothing; your plate does.
The forms on the shelf
- Sports drinks: 4 to 8 g of carbohydrates per 100 mL (typically 6 to 8) and about 20 to 40 mmol/L of sodium (46 to 92 mg per 100 mL) according to the Australian Institute of Sport (AIS); some have less than 10 mmol/L.
- "Zero sugar" tablets and powders: their value is judged by the sodium per reconstituted litre, to be compared with the 0.5 to 0.7 g per litre (21 to 30 mmol/L) the AIS cites for a replacement drink, not by the number of minerals on display.
- Oral rehydration salts: 50 to 60 mmol/L of sodium and 1.5 to 2 g of carbohydrates per 100 mL (AIS), designed for diarrhea.
Published reference values
- Sodium: Health Canada puts the average Canadian intake at 2,760 mg per day, against a target of 1,500 mg and a maximum of 2,300 mg; 58% of Canadians exceed the limit. An electrolyte packet adds to that on days without sweat.
- During prolonged exercise: the ISSN (International Society of Sports Nutrition) cites 300 to 600 mg of sodium per hour; the AIS cites 30 to 60 g of carbohydrates per hour for 1 to 2.5 hours of endurance and up to 90 g per hour beyond that.
- Potassium: no upper limit in adults with normal kidneys, but a risk of hyperkalemia in case of chronic kidney disease or use of ACE inhibitors, ARBs or potassium-sparing diuretics (NIH). Sodium in natural health products: Health Canada excludes it as a medicinal ingredient from its multivitamin and workout supplement monographs, because of hypertension.
When
During and after an effort of more than one hour, in the heat or with heavy sweating, drinking to thirst. The rest of the time, your plate covers potassium and already exceeds sodium.
Keep apart from
- ACE inhibitors, ARBs, potassium-sparing diuretics, salt substitutes: potassium adds up, and Health Canada contraindicates a potassium supplement with another supplemental source; this is a stacking to avoid, not a time interval.
- Non-steroidal anti-inflammatories during prolonged exercise: a possible risk factor for hyponatremia according to the 2015 consensus, contradictory data.
To mention to a professional
- Hypertension, heart or kidney failure, use of ACE inhibitors, ARBs or diuretics, events of more than 4 hours at a slow pace (risk factors for hyponatremia), pregnancy and breastfeeding: check with a health care professional.
From the plate first
Potassium according to the NIH: dried apricots 755 mg per half cup, cooked lentils 731 mg per cup, baked potato 610 mg, banana 422 mg, milk 366 mg per cup. Sodium: the Canadian diet already provides 2,760 mg per day on average.
Sources
- Baker, Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability, Sports Medicine 2017
- Hew-Butler et al., Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad 2015
- Australian Institute of Sport, Sports Supplement Framework, Electrolyte supplement
- Australian Institute of Sport, Sports Supplement Framework, Sports drinks
- NIH Office of Dietary Supplements, Potassium (Health Professional)
- Health Canada, natural health product monograph, Multi-Vitamin/Mineral Supplements
- Health Canada, natural health product monograph, Workout Supplements
- Health Canada, Health Canada publishes a report on sodium intake in Canada (2018)
- Kerksick et al., ISSN exercise and sports nutrition review update: research and recommendations, JISSN 2018
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.