Are isotonic drinks healthy? When should you drink them?
During physical exertion, the body loses water and electrolytes – primarily sodium – through sweat. During prolonged activity, the importance of replenishing energy also increases. This is precisely why isotonic drinks are popular amongst runners, cyclists and those who practise endurance sports. However, their benefits are not limited to hydration alone. The minerals they contain play a role in muscle function, the nervous system and the maintenance of electrolyte balance. We examine when an isotonic drink may be a better choice than water and which properties of its ingredients are supported by health claims authorised in the European Union.
What do isotonic drinks contain? How do the electrolytes in isotonic drinks work? When is an isotonic drink a better choice than water? How should you drink isotonic drinks correctly? What exactly do the EFSA and EU regulations confirm? Isotonic drinks, health benefits FAQ – frequently asked questions
What do isotonic drinks contain?
Water forms the basis of an isotonic drink, but its effectiveness also depends on the carbohydrates and electrolytes it contains. Carbohydrates provide energy during exercise, whilst sodium helps to replenish losses caused by sweating. Many products also contain potassium, magnesium, calcium and chlorides. The proportions of the ingredients and the osmolality – that is, the concentration of molecules dissolved in the drink – are important. It is precisely this carefully selected composition that enables a carbohydrate-electrolyte drink to aid water absorption during physical activity.
How do the electrolytes in isotonic drinks work?
Sodium – replenishes losses associated with sweating. It is the main electrolyte in extracellular fluid. It plays a role in regulating water balance, the transmission of nerve impulses and muscle function. During intense sweating, the body loses sodium, which is why it is an important component of sports drinks. EU health claims for carbohydrate-electrolyte solutions specify the required range of its content.
Potassium
Magnesium
Calcium
Chlorides – an important component of water and electrolyte balance. They are found, amongst other things, in sodium chloride and potassium chloride. They play a role in maintaining fluid and acid-base balance. The health claim regarding chlorides authorised in the EU, however, refers to their contribution to normal digestion through the production of hydrochloric acid in the stomach.
It is worth noting that not every isotonic drink contains all the minerals listed, and their presence does not automatically entitle the product to bear health claims. The product must meet the relevant conditions regarding the composition and content of a given ingredient.
When is an isotonic drink a better choice than water?
During a short training session lasting up to about an hour, water is usually sufficient, especially at moderate intensity. During longer sessions, often exceeding 60–90 minutes, carbohydrate intake and sodium replenishment also become important. An isotonic drink allows you to combine these functions in a single drink. This can be particularly useful during long-distance running, cycling, multi-hour competitions, demanding mountain hikes and intense activity in hot weather. However, your requirements depend on the duration of the training session, weather conditions and your individual rate of sweating.
How should you drink isotonic drinks correctly?
During prolonged exercise, it is best to consume fluids gradually, adjusting the amount according to your thirst and actual needs. There is no single serving size suitable for every athlete. Meals and the total amount of carbohydrates consumed are also important. You should not force yourself to drink excessive amounts of fluid. During exercise lasting several hours, this can lead to a dangerous drop in blood sodium levels. An isotonic drink therefore does not replace an individual hydration plan, but can be a practical part of it.
What exactly do the EFSA and EU regulations confirm?
Commission Regulation (EU) No 432/2012 authorises two claims regarding carbohydrate-electrolyte solutions:
They contribute to the maintenance of performance during prolonged endurance exercise.
They increase water absorption during physical exercise.
Isotonic drinks, health benefits
Isotonic drinks can support the body’s hydration and help it function properly during physical exercise. The electrolytes they contain play a role in muscle and nervous system function, whilst the carbohydrates provide energy. Properly formulated isotonic drinks can also increase water absorption and help maintain performance during prolonged endurance exercise. They offer the greatest benefits when their composition and method of use correspond to the body’s actual needs.
“A well-formulated isotonic drink provides more than just water during exercise. Its components support muscle and nervous system function as well as electrolyte balance, whilst carbohydrates can serve as an additional source of energy ”. Anna Zięba, Dietitian
FAQ – frequently asked questions
Are isotonic drinks healthy?
They can be a valuable part of staying hydrated during strenuous physical activity. Their usefulness depends on their composition and the type of exercise.
What electrolytes do isotonic drinks contain?
Most commonly sodium, potassium and chlorides, and depending on the formula, also magnesium and calcium.
Why is magnesium added to isotonic drinks?
Magnesium helps maintain electrolyte balance, supports normal muscle function and reduces feelings of tiredness and fatigue.
Is an isotonic drink better than water?
During prolonged exercise, a properly formulated isotonic drink may offer an advantage due to its sodium and carbohydrate content. For short bursts of activity, water is usually sufficient.
When is the best time to drink an isotonic drink?
First and foremost, during long or intense exercise, particularly when accompanied by significant sweating.
Is the sugar in isotonic drinks necessary?
Carbohydrates can provide energy during long-duration endurance exercise. Their presence therefore serves a specific sporting purpose.
Does every isotonic drink have its effects confirmed by the EFSA?
Not automatically. Health claims may only be used for products that meet specific compositional requirements.
Sources:
American College of Sports Medicine position stand. Exercise and fluid replacement https://pubmed.ncbi.nlm.nih.gov/17277604/ Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance https://pubmed.ncbi.nlm.nih.gov/26920240/ Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015 https://pubmed.ncbi.nlm.nih.gov/26102445/
ADDED:
10/11/2026
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