Are High-Sodium Electrolytes Better? Per Litre and Who They Suit

Better for the hours that cost about two litres of sweat, in an adult with no kidney or blood-pressure condition; not better for everyone, and not for an ordinary day. A high-sodium sachet of about 2 g of sodium is about 5 g of salt, roughly 80% of the NHS 6 g daily maximum in one drink, and the sodium in about two to two and a half litres of average sweat, which in 506 athletes carried about 0.8 g a litre.^{1, 2} The useful comparison is sodium per litre as mixed, and the useful ceiling is the 6 g. Part of electrolytes for athletes in the Wellgard electrolyte guide.

Evidence at a glance

• Studies: a sweat dataset of 506 athletes; a 26-triathlete race trial; two heat-chamber trials (8 men, 13 women); a 9-runner treadmill trial; a 233-finisher ultramarathon cohort; Cochrane and pooled analyses of 195 and 32 blood-pressure trials.
• Largest single analysis: 195 randomised trials of lower against higher sodium intake.³
• Strongest measured outcome: in 13 trained women, a concentrated sodium drink before cycling in 32 °C heat extended time to exhaustion from 78.7 to 98.8 minutes.⁴
• Not tested: no trial has compared a high-sodium sachet with a low-sodium one in the same athletes.

Sources checked on 17 October 2026.

Sodium or salt: which number is on the label?

Supplements print sodium; drinks and foods print salt. Salt is sodium chloride and about 39% of it is sodium, so salt divided by 2.5 is sodium and sodium times 2.5 is salt: 6 g of salt is 2.4 g of sodium, and a 2 g sodium sachet is 5 g of salt.² Where the sodium comes as citrate, the element is about 23 to 27% of the compound, and as bicarbonate about 27%, which is why a label that lists "sodium citrate 1,000 mg" is telling you about 250 mg of sodium. Read the element, in milligrams, per serving. How much salt a day has the daily arithmetic.

How strong is your drink per litre?

Divide the sodium per serving by the water the instructions tell you to use. Two packs with the same tablet can tell you different volumes, and the strength changes with them: 300 mg in 300 ml is 1,000 mg/L, in 500 ml it is 600 mg/L. The yardsticks are sweat, which ran from 400 to 1,600 mg/L across 506 athletes, and the 460 to 1,150 mg/L band the GB claims register sets for carbohydrate-electrolyte sports drinks.^{1, 5}

The last two rows are the same sachet in different bottles: the per-litre strength changes, the sodium you swallow does not. A low-sodium sachet of about 300 mg replaces about a third of a litre of average sweat; a high-sodium one of about 2 g replaces about two and a half. Neither figure is good or bad until you know how much you sweated. The weigh-yourself method on the runners' page tells you.

What does a high-sodium sachet add to a day?

About 5 g of salt, so about 80% of the NHS 6 g adult maximum in one drink, against a UK average intake that already runs at about 8.4 g a day from food.² The European Food Safety Authority puts a safe and adequate adult intake at 2.0 g of sodium a day, which is the whole of one such sachet.⁶ The same sachet also puts back the sodium in about two litres of average sweat, or in one litre of the saltiest sweat recorded, which is why it exists: a long, hot or salt-crusted session in an adult whose sodium is not already a medical matter.¹ On a day without that sweat, the sodium simply adds to the 8.4 g, which is why labels for this strength say one a day and why the low-sodium kind is the one for the warm desk day.

Who should be careful with high-sodium electrolytes?

Anyone with high blood pressure, heart failure or kidney disease, anyone on a medicine that holds sodium or potassium, and anyone pregnant, who asks the pharmacist first. In the 2020 Cochrane review of 195 trials, cutting sodium from about 203 to 65 mmol a day lowered systolic pressure by about 1 mmHg in people with normal blood pressure and nearly 6 mmHg in people with hypertension, high-quality evidence.³ Potassium travels with the sodium in most sachets: across 32 trials, extra potassium lowered blood pressure up to a difference of about 30 mmol a day and raised it above about 80 mmol a day in people on blood-pressure drugs, and high blood potassium is common in chronic kidney disease and with ACE inhibitors, angiotensin receptor blockers, spironolactone or amiloride.^{7, 8} The NHS adds that older people should not take potassium supplements unless advised to by a doctor.⁹ The cautions printed on a high-sodium pack, not for sodium-restricted diets or high blood pressure, are the short version of this section.

Does more sodium help performance?

In the trials, sodium changed body water and blood sodium; whether that changed performance depended on the setting. In a real half-ironman, 26 experienced triathletes took salt capsules carrying 113 mmol of sodium (about 2.6 g) or a cellulose placebo before and during the race: the salt group finished faster (P = 0.04), lost slightly less body mass and ended with higher blood sodium; funding is not stated in the abstract.¹⁰ In two small double-blind heat-chamber trials, a concentrated sodium drink of 164 mmol/L sipped from 105 minutes before exercise in 32 °C raised plasma volume 4.5% in 8 trained men and extended cycling to exhaustion from 78.7 to 98.8 minutes in 13 trained women; the men's drink held about 2.8 g of sodium, more than the NHS day, so it is a laboratory protocol, not a habit.^{4, 11}

Two field studies point the other way. Among 233 finishers of a 161 km ultramarathon in heat reaching 39 °C, the 15 who took no sodium supplements finished 3.2% lighter and the 138 who took them every segment 1.9% lighter; the authors regarded both as acceptable, so the cohort does not settle whether the sodium helped.¹² In 9 runners doing two 5-hour treadmill runs at 30 °C, capsules replacing all of their measured sweat sodium made no difference to how much they chose to drink, their fluid balance, heart rate or core temperature; blood sodium rose by 4 mmol/L against 1.¹³ So sodium for a heavy sweater stays sensible, sized to the sweat; the trials so far show no extra performance from sodium beyond what the sweat took out.

How do you compare cost like with like?

Per gram of what the product is for. A sodium-only tablet or sachet is priced fairly per gram of sodium; a carbohydrate-electrolyte drink is priced per gram of carbohydrate, because its job is fuel. Comparing a 300 mg sachet with a 2,000 mg sachet per serving says nothing until you divide by the sodium, and comparing either with a sugared sports drink mixes two jobs (sugar-free electrolytes vs sports drinks separates them). Divide the pack price by the total grams of sodium, or of carbohydrate, and the comparison is honest.

What we don't know

• No trial has compared a high-sodium sachet with a low-sodium one in the same athletes on the same course.
• The performance trials used salt capsules or a concentrated laboratory drink, not a flavoured sachet; the half-ironman trial's funding is not stated in its abstract.¹⁰
• Four in five athletes in the 506-person sweat dataset were male, and no trial has set sodium amounts for women.¹

Frequently asked questions

Is 2 g of sodium in one drink safe?

For an adult with no kidney or blood-pressure condition who has sweated it out, it is sized to the loss: about two litres of average sweat.¹ Without that sweat it is about 80% of the NHS 6 g of salt for the day, and with high blood pressure, heart failure or kidney disease the answer belongs to a pharmacist or GP.^{2, 3}

Can you split a high-sodium sachet?

Yes: half a sachet in the full volume of water halves the strength and the sodium, which suits a shorter or cooler session; the minerals come down with it, so the magnesium or potassium claim lines (56.25 mg and 300 mg a serving) may no longer be met.⁵

Is sodium citrate better than sodium chloride?

Neither is better; they carry different amounts of sodium per gram (about 25% against 39%), and citrate tastes less salty. Read the sodium line in milligrams, whichever compound it comes from.

Sources

1. Baker LB, et al. Observational, 506 athletes (404 male); sports-drink-maker research institute. J Sports Sci 2016. PubMed 26070030.
2. NHS. Salt in your diet. Reviewed 17 April 2023 (overdue); checked 17 October 2026. nhs.uk. UK 8.4 g: Public Health England, NDNS urinary sodium 2018 to 2019. gov.uk.
3. Graudal NA, et al. Cochrane review, 195 randomised trials; no industry funding. Cochrane Database Syst Rev 2020. PubMed 33314019.
4. Sims ST, et al. Double-blind crossover trial, 13 trained women; funding not checked. J Appl Physiol 2007. PubMed 17463297.
5. Department of Health and Social Care. GB nutrition and health claims register; retained Regulation (EU) 432/2012 annex. gov.uk.
6. EFSA Panel on Nutrition, Novel Foods and Food Allergens. Scientific opinion on dietary reference values for sodium. EFSA J 2019. PubMed 32626425.
7. Filippini T, et al. Dose-response meta-analysis, 32 randomised trials; publicly funded. J Am Heart Assoc 2020. PubMed 32500831.
8. Sarnowski A, et al. Narrative review; one author reports pharmaceutical grants and honoraria. Int J Nephrol Renovasc Dis 2022. PubMed 35942480.
9. NHS. Vitamins and minerals: others. Reviewed 3 August 2020 (overdue); checked 17 October 2026. nhs.uk.
10. Del Coso J, et al. Randomised controlled trial, 26 triathletes; funding not stated in the abstract. Scand J Med Sci Sports 2016. PubMed 25683094.
11. Sims ST, et al. Double-blind crossover trial, 8 trained men; funding not checked. Med Sci Sports Exerc 2007. PubMed 17218894.
12. Hoffman MD, Stuempfle KJ. Observational, 233 ultramarathon finishers; publicly funded. J Strength Cond Res 2016. PubMed 26907835.
13. McCubbin AJ, da Costa RJS. Double-blind randomised crossover trial, 9 runners, two 5-hour runs; academic authors. Int J Sports Physiol Perform 2024. PubMed 37944507.

General information, not medical advice. With high blood pressure, heart failure or kidney disease, or a medicine that affects sodium or potassium, ask a pharmacist or your GP before using a high-sodium electrolyte product.

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