Electrolytes
(4-5 minute read)
The health and fitness industry often portrays electrolyte supplements as essential for anyone who exercises. As the market expands alongside the growing influence of wellness culture, it is worth evaluating whether they are genuinely needed.
What are electrolytes?
Electrolytes are charged molecules that, when dissolved in water, conduct electricity. They are essential to many bodily functions, including maintaining fluid balance, muscle contractions and nerve functions.¹
The main component of blood is water, and electrolytes play a key role in keeping water where it should be. The primary electrolytes involved in fluid balance are sodium, potassium, and chloride. Sodium is found outside cells and helps draw water towards them; potassium is found within cells and helps retain it there; and chloride ensures the pressure of fluids inside and outside the cell remains balanced. We often also see magnesium and calcium in many electrolyte supplements which are recognised for their supporting role in hydration and muscle function.²
What is the purpose of electrolyte supplements?
When you exercise, your body generates heat as a byproduct of muscle activity. To regulate its temperature, it produces sweat, and sweat is not just water alone. Sweat contains electrolytes, primarily sodium and chloride, which are drawn out of the bloodstream as fluid moves to the skins surface.³
As sweat loss accumulates, electrolyte concentrations in the blood begin to shift. Since electrolytes are essential to fluid balance, muscle contraction and nerve function, significant losses without replenishment can lead to fatigue, muscle cramps, light-headedness and nausea. In more serious cases, significant sodium loss can lead to a condition called hyponatremia, where the blood becomes dangerously diluted.⁴
However, the body maintains electrolyte reserves across the blood, bones and muscle tissue. For many workouts, the natural losses are modest enough to be restored through diet and adequate water intake. Whether replenishment in the form of a supplement is necessary depends on a number of factors.⁵ This distinction matters because taking these supplements frequently when not required can negatively impact health.⁶
What are the guidelines around taking electrolyte supplements?
Research points to several key factors that determine whether electrolyte supplementation is necessary.
Session duration: The most consistently cited threshold for considering electrolyte supplementation is exercise lasting longer than 60 minutes, particularly when sessions extend towards 90 minutes or more, resulting in substantial sweat losses. For many sessions within 60 minutes, electrolyte replacement is generally not required when a balanced diet is consumed. Beyond it, particularly in demanding conditions, supplementation becomes a consideration.⁷
Heat and environment: Temperature and environmental conditions can significantly increase sweat rate and, therefore, electrolyte loss. A 90-minute gym session in a cool environment is not directly comparable to a 90-minute run in summer heat, where sweat losses are likely to be much greater. When sweat rate is elevated in hot conditions, endurance athletes may require additional sodium replacement, with recommendations often ranging from 300 to 600 mg per hour of activity. Therefore, exercise intensity and environmental conditions should also be considered alongside duration when determining electrolyte requirements.⁸
Individual sweat rate: Sodium loss varies considerably between individuals, ranging from approximately 200 mg to 2,000 mg per litre of sweat. This variation is influenced by factors such as genetics, heat acclimatisation, fitness level and diet. Practical indicators of higher sodium loss may include sweat that tastes noticeably salty, white residue left on the skin or clothing after exercise, or salt crystals forming on the skin as sweat dries.⁹
Diet: For individuals consuming a well-balanced diet, electrolyte losses from exercise can typically be restored through food alone. Sodium is found in many everyday foods, while potassium, magnesium and calcium are readily available through sources such as fruits, vegetables, nuts and dairy products. Supplementation becomes more relevant when electrolyte losses are consistently greater than what can be replenished through diet alone.¹⁰
The risks of unnecessary supplementation
Popular electrolyte sachets can commonly constitute of up to 1000mg of sodium and smaller amounts of potassium, magnesium and calcium. Meaning, one sachet can contain up to 2.5g of salt. The World Health Organisation recommends less than 5g of salt per day,¹¹ therefore one sachet can make up half of a person's daily salt intake.
We can confidently say that increased salt intake raises the risk of high blood pressure and, consequently, cardiovascular disease, which remains a leading cause of mortality globally.¹² In the UK, the average adult salt intake is approximately 7–8 g per day. Although this remains above the recommended limit, intake has declined over the past 20 years from approximately 9.5 g per day. This reduction is largely attributed to sustained public health efforts, including the reformulation of foods by manufacturers, improved food labelling and greater public awareness.¹³
Considering this information, it may seem counterintuitive to consume large amounts of sodium through supplementation in the pursuit of improved health. This is particularly relevant given that public health initiatives continue to encourage reductions in sodium intake due to its association with increased cardiovascular risk. This concern is compounded by a significant gap in the evidence. Much of the research on electrolyte supplementation has focused on athletic performance, leaving comparatively little evidence on the effects of routine supplementation in non-athletes. This gap has become increasingly important as electrolyte products are being marketed more widely to the general population.¹⁴ The Harvard T.H. Chan School of Public Health states there is no evidence that electrolyte drinks are a healthier choice than water for the average person,¹⁵ while the American Heart Association has warned that excess sodium raises blood pressure and that overuse of electrolyte drinks can be problematic.¹⁶ With population-level sodium intake already well above recommended limits, routine supplementation in non-athletes may be quietly adding to an existing public health problem.
In the right context, electrolyte supplements can be a valuable tool. For endurance athletes and those performing high-intensity exercise, they serve a clear physiological purpose by replacing sodium lost through prolonged sweating. As electrolyte products are increasingly marketed beyond competitive sport, their use is expanding among recreational exercisers and the general population, where the need for supplementation is often less clear. Used appropriately, electrolyte supplements have a legitimate place, but without consideration of individual need, they risk contributing to, rather than reducing, an existing public health concern.
Recommendations
When considering electrolyte supplementation, factors such as workout duration, environmental heat, exercise intensity and individual sweat rate should be taken into account. If the primary appeal is increasing mineral intake, including potassium, magnesium or calcium, dietary improvements may be a more appropriate approach.
If supplementation is warranted, the product should reflect the demands of the activity. A lower-sodium option such as SiS GO Hydro Tablets may be sufficient for light to moderate hydration support. Higher-sodium products such as Puresport’s Ultra Electrolytes may be better suited to endurance events like marathons or long-distance cycling, where prolonged sweating can result in greater sodium losses and increased requirements for replenishment.
References:
1. Armstrong LE. Rehydration during endurance exercise: challenges, research, options, methods. Nutrients. 2021;13(3):887. doi:10.3390/nu13030887.
2. Shrimanker I, Bhattarai S. Electrolytes. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan– [updated 2023 Jul 24].
3. Baker LB. Physiology of sweat gland function: the roles of sweating and sweat composition in human health. Temperature (Austin). 2019;6(3):211-259. doi:10.1080/23328940.2019.1632145.
4. Buck E, McAllister R, Schroeder JD. Exercise-associated hyponatremia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan– [updated 2023 Jun 12]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572128/
5. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS; American College of Sports Medicine. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390. doi:10.1249/mss.0b013e31802ca597.
6. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium. Washington (DC): The National Academies Press; 2019. doi:10.17226/25353.
7. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016;116(3):501-528. doi:10.1016/j.jand.2015.12.006.
8. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand: Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377–390. doi:10.1249/mss.0b013e31802ca597.
9. Barnes KA, Anderson ML, Stofan JR, et al. Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss in athletes. J Sports Sci. 2019;37(20):2356–2366. doi:10.1080/02640414.2019.1633157.
10. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016;116(3):501–528. doi:10.1016/j.jand.2015.12.006.
11. World Health Organization. Guideline: Sodium intake for adults and children. Geneva: World Health Organization; 2012.
12. World Health Organization. WHO guideline on sodium intake and health. Geneva: World Health Organization; 2023.
13. He FJ, Brinsden HC, MacGregor GA. Salt reduction in the United Kingdom: a successful experiment in public health. J Hum Hypertens. 2014;28(6):345-52. doi:10.1038/jhh.2013.105.
14. Maughan RJ, Burke LM, Dvorak J, Larson-Meyer DE, Peeling P, Phillips SM, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439-455. doi:10.1136/bjsports-2018-099027.
15. Harvard T.H. Chan School of Public Health. The Nutrition Source: Sports drinks [Internet]. Boston (MA): Harvard T.H. Chan School of Public Health; 2025 [cited 2026 Aug 2]. Available from: https://nutritionsource.hsph.harvard.edu/sports-drinks/
16. American Heart Association. Electrolytes can give the body a charge, but try not to overdo it [Internet]. Dallas (TX): American Heart Association; 2024 Jun 19 [cited 2026 Aug 2]. Available from: https://www.heart.org/en/news/2024/06/19/electrolytes-can-give-the-body-a-charge-but-try-not-to-overdo-it