Hypotonic, isotonic, hypertonic drink: what are the differences?

When you're active, whether it's training, working, or just going about your daily life, maintaining adequate hydration is essential to staying healthy and performing at your best. Here's some information to help you figure out which type of drink is right for you, as hypertonic , hypotonic, and isotonic drinks offer different hydration benefits. They're usually made up of sugar and minerals and differ in their osmolarity. So, are you ready to learn more?

What is osmolarity?

The osmolarity of a beverage (measured in mOsm/L) quantifies the number of active particles dissolved in a solution. A beverage is isotonic when its osmolarity is close to that of blood, which is of the order of 280 to 300 mOsm/L.

Osmotic pressure is a phenomenon that occurs when two solutions of different concentrations, i.e. what you drink and your blood plasma, are separated by a membrane (here the walls of your intestine). Water tends to move from the less concentrated solution (hypotonic) to the more concentrated solution (hypertonic) in order to equalize the concentrations of solutes on either side of the membrane.

How do these concepts apply to beverages?

Hypotonic drinks

A drink is said to be hypotonic if its concentration of solutes (sugars and electrolytes such as sodium, magnesium, potassium, etc.) is lower than that of blood plasma. Therefore, when you drink the solution, it tends to be absorbed quickly into the bloodstream as water leaves the more dilute solution of the drink to balance the concentration in your body. In other words, it is less concentrated in solutes than blood, with an osmotic pressure lower than 280 mOsm/L.

Why are hypotonic drinks interesting?

Absorption is rapid , due to their low concentration of solutes. In fact, these drinks are absorbed more quickly by the body.

Hydration is more effective because they allow rehydration which is particularly useful in cases of mild dehydration.

Digestion is facilitated because they do not cause significant osmotic stress (disturbances suffered by the cells). Hypotonic drinks are generally well digested and do not cause digestive disorders.

During prolonged exercise or in hot weather, the body loses water and electrolytes, particularly through sweating. Hypotonic drinks are particularly suitable for replacing these water losses while restoring electrolyte balance. Their ability to be absorbed easily means that water is available to rehydrate cells and tissues quickly.

We can therefore say that hypotonic drinks are effective and practical hydration solutions, particularly useful for rehydrating quickly after moderate physical effort or in case of dehydration. Use a tablet diluted in 250 ml of water, get your hypotonic drink, and stay Hydratis !

Isotonic drinks

A drink is said to be isotonic if its solute concentration is similar to that of blood plasma. The water in an isotonic drink is absorbed at a relatively constant rate because there is no significant difference between the drink and your body. These drinks are often used during exercise to maintain hydration and quickly provide carbohydrates (sugar) and electrolytes lost through sweat. In other words, it has the same solute concentration as blood with an osmotic pressure between 280 and 300 mOsm/L.

What is the role of isotonic drinks?

They play an important role in maintaining your body's fluid and electrolyte balance to help keep you energized.

They ensure optimal hydration while compensating for losses in mineral salts (sodium, potassium, magnesium, etc.).

These drinks allow for rapid and efficient absorption of liquids compared to still water, thus promoting good water balance at any time of the day!

It is important to know that the carbohydrates present in these drinks provide rapidly available energy to support physical performance.

In addition, their balanced composition makes them ideal for effective recovery after exercise, by quickly rehydrating the body and helping to restore mineral salt reserves. They help prevent fatigue and muscle cramps related to physical effort that can be due to a lack of hydration and electrolyte imbalances.

Isotonic drinks are perfectly suited for athletes looking to optimize their water balance, obtain an energy intake and an effective recovery. But they are also intended for users wanting to prevent daily fatigue. You can obtain a Hydratis isotonic drink by adding 2 tablets to a 250 mL glass of water.

Hypertonic drinks

A hypertonic drink is characterized by its higher concentration of solutes compared to blood. When you consume a hypertonic drink, it contains more dissolved particles than your blood. This means that the water in your body is drawn to the drink to dilute this high concentration of solutes. In other words, it is more concentrated in solutes than blood, with an osmotic pressure greater than 300 mOsm/L.

These drinks cause temporary dehydration by initially slowing down the absorption of water by your body. They can still be useful in certain situations such as prolonged exercise, where sweating is less and therefore dehydration is less significant. However, it is important to accompany them with another source of hydration.

Why consume Hydratis?

Hydratis lozenges are composed of electrolytes, namely magnesium which reduces fatigue and cramps and potassium which contributes to proper muscular and nervous functioning, but also antioxidants such as zinc and manganese which fight against cellular aging and fatigue.

It is then a concentrate of active ingredients that allows you to improve your health! Below you will find some benefits depending on the type of drink consumed:

	1 Hydratis tablet in a 250ml glass of water	2 Hydratis tablets in a 250ml glass of water
Beverage	hypotonic	isotonic
Solute concentration	lower than that of blood plasma	similar to blood plasma
Absorption into your body	rapidly absorbed into the blood	absorbed at a constant rate
Use	daily to improve your hydration	around physical effort (before, during and after)
Benefits	allows good water rebalance, better energy and better concentration	supports performance and replenishes energy and electrolyte reserves

On your marks, get set? Grab your lozenges !

Bibliography

Pérez-Castillo ÍM, Williams JA, López-Chicharro J, Mihic N, Rueda R, Bouzamondo H, Horswill CA. Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited. Nutrients. 2023 Dec 20;16(1):17. doi:10.3390/nu16010017. PMID: 38201848; PMCID: PMC10781183.

Rowlands DS, Kopetschny BH, Badenhorst CE. The Hydrating Effects of Hypertonic, Isotonic and Hypotonic Sports Drinks and Waters on Central Hydration During Continuous Exercise: A Systematic Meta-Analysis and Perspective. Sports Med. 2022 Feb;52(2):349-375. doi:10.1007/s40279-021-01558-y. Epub 2021 Oct 30. PMID: 34716905; PMCID: PMC8803723.

Vujovic P, Chirillo M, Silverthorn DU. Learning (by) osmosis: an approach to teaching osmolarity and tonicity. Adv Physiol Educ. 2018 Dec 1;42(4):626-635. doi: 10.1152/advan.00094.2018. PMID: 30303411.