Electrolytes

What are electrolytes and what do they do in the body?

Electrolytes are mineral salts such as sodium, potassium, and chloride that carry an electric charge when dissolved in water. This page centers on sodium, the electrolyte most often cited in sweat loss and supplement products. According to the report of the National Nutrition Council Salt Science Commission (of the Ministry of Health’s General Directorate of Public Health), salt (NaCl) has important roles in regulating fluid balance and thus blood pressure in the body, in maintaining acid-base balance, and in transmitting impulses in the nerve-muscle system. ^[12]

Two separate questions can get mixed up here: the role of electrolytes in the body and the benefit of extra supplementation. That a role exists does not mean every person needs to consume more. The evidence varies with who loses how much and which outcome is examined.

How much sodium is lost in sweat, and does it vary from person to person?

The ACSM position statement states that sweat rate and sweat electrolyte content vary significantly between individuals, so individualized fluid programs are recommended; individual sweat rate can be estimated by measuring body weight before and after exercise. ^[1]

In a retrospective analysis trying to explain sweat sodium concentration, 1,944 sweat tests from 1,304 people were pooled. The models were found to explain only 17–23% of the variation; the most important factors were energy expenditure and time of year (an indicator of heat acclimatization). Age group, race, relative humidity, exercise duration, and sodium taken through diet or during exercise showed no significant effect. According to the affiliation information on PubMed, the authors work at the research unit of a sports drink manufacturer. ^[7]

Do electrolyte drinks during exercise provide benefit over water?

ACSM states that drinks containing electrolytes and carbohydrate during exercise may provide benefit over water alone “under certain conditions”; in its abstract, the text does not give a single condition or effect size. ^[1]

For ultramarathon, the ISSN statement says that, to reduce the likelihood of hyponatremia, electrolytes (chiefly sodium) may be needed at concentrations higher than most commercial products provide (>575 mg/L sodium), and that fluid and electrolyte needs increase in hot, humid conditions. This is a consensus text; unlike the ACSM text, it covers only single-stage ultramarathons. ^[5]

Alongside these two statements there is an observational dataset. In the 80 km stage of a 6-stage, 250 km ultramarathon held in Chile/Patagonia, Namibia, and Mongolia, 266 runners were followed; 161 had both pre-race weight and total sodium intake data. Sodium intake showed no significant association with speed, finish time, or ranking; the result did not change when sodium intake was analyzed as a continuous variable or in the 109 normonatremic runners. Dehydrated runners performed better than runners who took in excess fluid. The study is not randomized; intake was reported by questionnaire. ^[6]

What causes exercise-associated hyponatremia?

The Wilderness Medical Society guideline defines exercise-associated hyponatremia as serum or plasma sodium falling below the reference range (135 mmol/L) during or up to 24 hours after prolonged physical activity. The same guideline states that the condition most often shares symptoms with heat exhaustion and heat stroke, and that failure to distinguish them leads to poor outcomes. ^[4]

In the 2002 Boston Marathon, 766 participants were enrolled one to two days before the race; usable post-race blood samples were obtained from 488 (64%) of them. Hyponatremia (≤135 mmol/L) was found in 13% of participants and critical hyponatremia (≤120 mmol/L) in 0.6%. In multivariable analysis, hyponatremia was associated with weight gain during the race (OR 4.2; 95% CI 2.2–8.2), a race time over 4 hours (OR 7.4 compared with under 3.5 hours; 95% CI 2.9–23.1), and extremes of body mass index; female sex, the composition of fluids taken, and NSAID use were not found to be associated. ^[2]

A 2022 review states that exercise-associated hyponatremia is largely due to excessive consumption of hypotonic fluids and the resulting weight gain, that the main risk factors are inappropriate arginine vasopressin secretion, long exercise duration, and small body mass, and that NSAID intake contributes to a smaller extent. The same review says that monitoring fluid intake and loss, sodium supplementation, and heat acclimatization “may mitigate” the fall in blood sodium. ^[3] That is, the evidence points to hyponatremia being associated with fluid excess rather than salt deficiency; the preventive effect of sodium supplementation has not been definitively measured.

Do electrolytes prevent cramps?

The cause of exercise-associated muscle cramps (EAMC) is disputed. The 2022 evidence-based review states that EAMC is due not to a single cause but to a combination of internal and external factors specific to the person and the conditions, and that for prevention, strategies aimed at individual risk factors may be more effective than general advice such as “drink more fluid.” ^[9]

In a small crossover study, 13 college men with a history of cramping were tested in a hot environment of 37 °C with a calf-fatiguing protocol. With a carbohydrate-electrolyte drink with added sodium chloride, 9 participants cramped, and in the trial with no fluid given, 7 participants cramped. In the 7 people who cramped in both trials, exercise time lengthened to 36.8 ± 17.3 minutes with the drink (14.6 ± 5.0 minutes in the no-fluid trial; p < 0.01). The authors concluded that dehydration and electrolyte loss are not the only cause, because 69% of participants cramped even when hydrated and electrolyte-supplemented. ^[8]

Oral rehydration solution (ORS) is used in diarrhea; is it the same as electrolyte supplementation?

Oral rehydration solution containing electrolytes is a formula used in fluid loss such as diarrhea, and it is an evidence area separate from athletic supplements. The Cochrane review (Hahn et al., 2002) compared reduced-osmolarity ORS with the WHO standard ORS in children with acute diarrhea. Unplanned intravenous fluid infusion had been reported in 11 studies; in a meta-analysis of 8 studies, less infusion was needed with the reduced-osmolarity solution (OR 0.59; 95% CI 0.45–0.79). Stool volume and vomiting decreased; no marked difference in the incidence of hyponatremia was found between the two arms. The result applies to children admitted to hospital and compares the two formulas with each other, not ORS with no treatment. ^[10]

What are the reference values for daily sodium intake?

EFSA (2019) stated that there were insufficient data to derive an average requirement (AR) or population reference intake (PRI) for sodium. Instead, it stated that a sodium intake of 2.0 g/day is the level at which there is sufficient confidence for a reduction in cardiovascular disease risk in the general adult population and which would allow most adults to maintain sodium balance, and it assessed 2.0 g of sodium/day as a “safe and adequate intake” for the general EU adult population; the same value applies to pregnant and breastfeeding women. For children, “safe and adequate” values were given as 1.1 g/day at ages 1–3, 1.3 g/day at ages 4–6, 1.7 g/day at ages 7–10, and 2.0 g/day at ages 11–17; for infants aged 7–11 months, an adequate intake (AI) of 0.2 g/day was proposed. ^[11]

The Salt Science Commission report states that more than 2 g of sodium or more than 5 g of salt per day poses a risk of high blood pressure, heart disease, and stroke; it relays that WHO recommends consumption of 5 g per day. ^[12]

What is the picture on salt consumption and “electrolyte” expectations in Türkiye?

According to the Türkiye studies section of the same report, in the SALTurk1 study (2008), based on 24-hour urinary sodium excretion, adult per-person daily salt consumption was found to be 18 g, and in the SALTurk2 study conducted in 4 provinces in 2012 it was 15 g (the report’s executive summary gives the 2008 SALTÜRK value as 15 g; there is this discrepancy between the two sections); the Türkiye Excess Salt Consumption Reduction Action Plan has been in effect since 2011. In the 2017 Türkiye Nutrition and Health Survey (total of sodium from foods and added salt), daily per-person consumption was found to be 10.2 g; the report states that this is twice the recommended amount. ^[12] The report also states that there is no scientific data that “various salts on the market under different names” have beneficial health effects and that the main component of all types of salt is NaCl. ^[12]

This picture shows that the question of “daily electrolyte supplementation” for the general population has not been measured, while the problem that has been measured is excess. Athletes who sweat or people experiencing fluid loss are a separate group and are addressed separately in the sections above.

Who should be cautious?

• People with high blood pressure: The Salt Science Commission report states that the most important determinant of blood pressure level is dietary sodium and that high sodium intake poses a risk of high blood pressure, heart disease, and stroke. ^[12]
• People with kidney disease: The same report lists reducing salt consumption as one of the effective methods in reducing the risk of kidney disease. ^[12]
• People who drink large amounts of fluid during long-duration exercise: Exercise-associated hyponatremia has been found to be associated with excess fluid intake and weight gain; its symptoms overlap with heat exhaustion and heat stroke. ^{[2] [4]}
• The 4–10 age group: The Restricted Substances List sets a separate, lower sodium limit for this age group than for ages 11 and older. ^[14]

What is the status as a supplement in Türkiye?

In Türkiye, approval from the Ministry of Agriculture and Forestry is mandatory for every food supplement to be placed on the market; applications for imported products can be made only to the Istanbul and Ankara Provincial Directorates. ^[13] In the Ministry’s Restricted Substances List for food supplements (last updated September 21, 2026), the sodium row is salt-derived: 100 mg/day for ages 4–10 and 200 mg/day for ages 11 and older (published June 27, 2016 for ages 11 and older; March 27, 2017 for ages 4–10). The chloride row is also salt-derived and carries a value of 200 mg/day in the 11 years and older column. ^[14]

These limits relate to the amount contained in the food supplement. EFSA’s 2.0 g/day value and the 5 g salt value in the Commission report cover total intake from foods; therefore they cannot be compared in the same unit and the same scope.

Evidence table: claim, population, and limits

This guide does not recommend personal doses or treatment; in cases of diarrhea, vomiting, chronic disease, and regular medication use, the decision depends on individual clinical assessment.