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Which Drinks Contain Electrolytes? Milk, Coconut Water and Sachets
In this article
- Which drinks contain electrolytes?
- What is the best drink to replace electrolytes?
- Is milk an electrolyte drink?
- Is coconut water enough?
- Are sports drinks and electrolyte sachets the same thing?
- How do you make an electrolyte drink at home?
- Who should not drink electrolyte drinks?
- What we don't know
- Frequently asked questions
Milk, tomato juice, coconut water, pharmacy rehydration sachets, isotonic sports drinks and electrolyte sachets all contain electrolytes, in very different proportions. A 250 ml glass of semi-skimmed milk carries about 108 mg of sodium, 390 mg of potassium and 300 mg of calcium; a glass of fresh coconut water about 700 mg of potassium and 275 mg of sodium, though cartons vary; a pharmacy rehydration sachet about 300 mg of sodium with glucose; and electrolyte sachets from a few hundred milligrams to about 2 g, depending on whether they are for daily use or heavy sweat.2, 3 Which is best depends on what you have lost: glucose plus sodium for a stomach bug, sodium for sweat, and for an ordinary thirsty afternoon, water. This is the drinks spoke of the Wellgard electrolytes guide.
Sources checked on 30 October 2026.
Which drinks contain electrolytes?
Sodium and potassium per typical serving, from the UK composition tables, the rehydration sachet's product information, the register's definition of a carbohydrate-electrolyte drink and typical sachet labels.2, 3, 5
| Drink | Serving | Sodium | Potassium | What else is in it |
|---|---|---|---|---|
| Semi-skimmed milk | 250 ml | 108 mg | 390 mg | 300 mg calcium, 9 g protein, 12 g lactose |
| Coconut water | 250 ml | about 275 mg fresh; cartons vary | about 700 mg | About 12 g sugar, about 70 mg calcium |
| Orange juice | 150 ml | 2 mg | 240 mg | About 13 g sugar |
| Tomato juice | 150 ml | 345 mg | 345 mg | Salted in processing |
| Cola | 330 ml | 17 mg | 3 mg | About 36 g sugar, or sweeteners; caffeine |
| Black tea or filter coffee | 250 ml | trace | up to about 230 mg (coffee) | Caffeine |
| Squash with a quarter teaspoon of salt per litre | 500 ml | about 300 mg | trace | About 26 mmol/L sodium, inside the isotonic band |
| Isotonic sports drink (carbohydrate-electrolyte solution) | 500 ml | 230 to 575 mg (20 to 50 mmol/L) | varies, often small | 40 to 175 kcal of fast sugar, by definition |
| Pharmacy oral rehydration sachet | 200 ml | about 300 mg (around 60 mmol/L) | about 160 mg | Glucose and citrate; a medicine for diarrhoea |
| Daily electrolyte sachet (sugar-free) | 200 to 500 ml | 200 to 500 mg | 150 to 300 mg | Often magnesium at 15% NRV or more, some calcium and vitamins |
| High-sodium sachet for heavy sweat | 500 ml | 1,000 to 2,000 mg (2.5 to 5 g salt) | 300 to 500 mg | Magnesium and calcium at higher levels; check the sugar line |
What is the best drink to replace electrolytes?
After vomiting and diarrhoea, the loss is water with sodium, potassium and chloride, and the NHS points anyone with dehydration signs to a pharmacy rehydration sachet; the sachet's glucose is there because it carries sodium and water across the gut wall.3, 6, 7 In mild cases, 647 minimally dehydrated children did better on half-strength apple juice followed by whatever they would drink than on an electrolyte solution, with treatment failure in 16.7% against 25.0%.8 In the beverage hydration index trial, funded by a hydration research institute whose advisory board the lead author chaired, each of 72 men drank a litre of still water and of three of the 12 other drinks: over four hours a rehydration solution, full-fat milk and skimmed milk left about 300 g less urine than still water, while cola, diet cola, tea, coffee, lager, orange juice, sparkling water and a sports drink were no different from water.1
Is milk an electrolyte drink?
Functionally, yes, and a good one. Semi-skimmed milk carries 43 mg of sodium, 156 mg of potassium and 120 mg of calcium per 100 ml.2 In a dairy-industry-funded trial of 11 adults dehydrated by exercise in the heat, low-fat milk, with or without added salt, left them in positive fluid balance five hours later where water and a sports drink did not, with about half the urine output.9 It is not a substitute for a rehydration sachet in a child with diarrhoea.6
Is coconut water enough?
For potassium, generously; for sodium, it depends on the carton. The UK tables give fresh coconut water 280 mg of potassium and 110 mg of sodium per 100 g, while a paper funded by a coconut water supplier quotes about 200 mg and 75 mg, varying by palm.2, 4 Sweat runs at about 0.8 g of sodium a litre, so the label's sodium line decides whether a carton suits a salty sweat.10 In 12 trained men dehydrated by an hour on a treadmill, coconut water, a sports drink and bottled water restored body mass and fluid measures equally, and the coconut water drinkers reported more bloating.4 So coconut water is above all a potassium drink.
Are sports drinks and electrolyte sachets the same thing?
A carbohydrate-electrolyte solution, the isotonic sports drink, is defined in Great Britain's health claims register as a drink with 80 to 350 kcal per litre from carbohydrate, at least three quarters of it from fast sugars, 20 to 50 mmol/L of sodium and an osmolality of 200 to 330 mOsm/kg; only those may carry the register's water-absorption and endurance wording.5 The glucose drinks sold in corner shops carry about 26 mg of sodium per 100 ml: sugar drinks with a little sodium.2 An electrolyte sachet is a food supplement. A sugar-free sachet carries too little carbohydrate to meet the carbohydrate-electrolyte definition and may not use its wording; what it may say is what its minerals do, and for magnesium at 15% NRV or more that includes that magnesium contributes to electrolyte balance.5
How do you make an electrolyte drink at home?
A quarter of a teaspoon of table salt is about 1.5 g, which is 600 mg of sodium; stirred into a litre of diluted squash it gives about 26 mmol/L, inside the register's isotonic band, with the squash supplying sugar or sweetener and a splash of orange juice adding potassium.5 What a kitchen cannot make is an oral rehydration solution for a child with diarrhoea: the NHS route for a child with dehydration signs is the pharmacist or 111, not a home recipe or flat cola; rehydration sachets vs electrolyte drinks goes through illness by age.6, 7
Who should not drink electrolyte drinks?
The sodium and potassium set the list. In a Cochrane review, cutting sodium lowered systolic blood pressure by about 1 mmHg in white participants with normal blood pressure and nearly 6 mmHg in those with hypertension, so anyone with high blood pressure, heart failure or kidney disease asks a pharmacist or GP before adding salted drinks, and a high-sodium sachet counts towards the NHS 6 g salt maximum.11, 12 Potassium is the concern in chronic kidney disease and for anyone on an ACE inhibitor, an angiotensin receptor blocker, spironolactone or amiloride, where high blood potassium is common and can be dangerous.13, 14 Rehydration sachets are not for self-treatment in kidney disease or diabetes, and under-twos see a doctor.3 Do you need to drink electrolytes every day? takes the daily-use question in full.
What we don't know
- How much sodium UK coconut water cartons carry: the UK figure comes from an older analysis of fresh coconut and the supplier-funded paper quotes a lower one, so the label is the guide.2, 4
- Whether electrolyte sachets hydrate better than water: the beverage hydration index trial did not test them.1
Frequently asked questions
Do electrolytes hydrate you better than water?
The hydration index trial compared a rehydration solution, milk and other drinks with water, not electrolyte sachets: the rehydration solution and milk were retained longer than water, while a sports drink, cola, juice, tea and coffee were not.1
Can I just put salt in my water?
Yes: a quarter teaspoon in a litre gives about 26 mmol/L of sodium, the same band as an isotonic drink. It replaces sodium only; it is not a rehydration solution for a sick child.5, 6
Which food is highest in electrolytes?
For sodium, cured meats and cheese; for potassium, dried dates (727 mg per 100 g), boiled potatoes (365 mg), bananas (330 mg) and pulses.2, 12
When is the best time to drink electrolytes?
When you are losing them: during and after long, sweaty exercise, since sweat carries about 0.8 g of sodium a litre, and during vomiting and diarrhoea with signs of dehydration, a pharmacy sachet.6, 10
Sources
- Maughan RJ, et al. A randomised trial to assess the potential of different beverages to affect hydration status. American Journal of Clinical Nutrition, 2016. Randomised crossover trial, 72 men, 4 hours per drink; funded by a hydration research institute whose advisory board the lead author chaired. PubMed 26702122.
- Public Health England. McCance and Widdowson's Composition of Foods Integrated Dataset (CoFID), 2021. Food composition dataset. gov.uk.
- Oral rehydration salts sachet. Summary of Product Characteristics, sections 2 and 4.4. Date of revision 30 June 2023. medicines.org.uk.
- Kalman DS, et al. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. Journal of the International Society of Sports Nutrition, 2012. Randomised crossover trial, 12 men; supplier-funded. PubMed 22257640.
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. Updated 19 May 2026. gov.uk.
- NHS. Diarrhoea and vomiting. Page last reviewed 21 December 2023. nhs.uk/symptoms/diarrhoea-and-vomiting.
- Hahn S, Kim S, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children. Cochrane Database of Systematic Reviews, 2002. Systematic review of randomised trials, 8 pooled for the main outcome; funding not stated on PubMed. PubMed 11869639.
- Freedman SB, et al. Effect of dilute apple juice and preferred fluids vs electrolyte maintenance solution on treatment failure among children with mild gastroenteritis. JAMA, 2016. Randomised single-blind trial, 647 children aged 6 to 60 months; non-government funding listed on PubMed. PubMed 27131100.
- Shirreffs SM, et al. British Journal of Nutrition, 2007. Crossover trial, 11 people, four drinks; dairy-industry-funded. PubMed 17459189.
- Baker LB, et al. Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. Journal of Sports Sciences, 2016. Retrospective analysis, 506 athletes; authors employed by a sports-drink company's research institute. PubMed 26070030.
- Graudal NA, Hubeck-Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database of Systematic Reviews, 2020. Systematic review of randomised trials, 195 included references; no salt-industry funding. PubMed 33314019.
- NHS. Salt in your diet. Page last reviewed 17 April 2023 (review overdue). nhs.uk/live-well/eat-well/food-types/salt-in-your-diet.
- Filippini T, et al. Potassium intake and blood pressure: a dose-response meta-analysis of randomized controlled trials. Journal of the American Heart Association, 2020. Dose-response meta-analysis, 32 randomised trials; non-government funding listed on PubMed. PubMed 32500831.
- Sarnowski A, et al. Hyperkalemia in chronic kidney disease: links, risks and management. International Journal of Nephrology and Renovascular Disease, 2022. Narrative review; one author declares pharmaceutical grants and honoraria. PubMed 35942480.
Spotted something out of date? Email support@wellgard.co.uk with the page address and the sentence.
This article is general information, not medical advice. A child with diarrhoea and signs of dehydration needs a pharmacist or 111, not a home-made drink; with high blood pressure, heart failure or kidney disease, or on a blood-pressure medicine, ask a pharmacist before using salted drinks.
