Drinking plenty matters. But what we drink matters just as much. So if you’re now wondering: can drinks really hydrate better or worse? Yes, they can! Because water absorption in the body follows a specific system. For that, we need to head back to biology class for a moment:

How your body absorbs water

When we drink, fluid passes through the stomach into the small intestine. The water it contains is absorbed by the intestinal wall and then enters the bloodstream. The cell membrane of the intestinal wall is only semi-permeable: it lets water molecules pass through, but not dissolved particles such as electrolytes and sugar. What determines water absorption is osmotic pressure – the concentration of particles in the fluid relative to that in the blood. This is where the terms isotonic, hypotonic and hypertonic come in.

Isotonic

(iso = equal / tonos = pressure)

Isotonic solutions have the same osmotic pressure as our blood and therefore the same particle concentration per litre. To be precise, that's 280 mmol/kg. They supply the body with water neither faster nor more slowly.

Examples of isotonic drinks include diluted fruit juices and alcohol-free beer.

Hypertonic

(hyper = more / tonos = pressure)

Hypertonic solutions have a higher osmotic pressure than our blood, meaning more particles per litre. Their particle concentration is above 300 mmol/kg. They do the opposite of hypotonic solutions and are absorbed more slowly. Classic examples are soft drinks and lemonades.

Hypotonic

(hypo = less / tonos = pressure)

Hypotonic solutions have a lower osmotic pressure than our blood – in other words, fewer particles per litre. This means more water flows through the cell membranes into the blood and the body is supplied with fluid more quickly. Drinks below 260 mmol/kg may be described as hypotonic. Hypotonic drinks include mineral water, herbal teas, whey products and slightly hypotonic sports drinks such as the Hydration Helper®.

The ideal balance for your fluid levels

So mineral water is hypotonic too. Doesn't that mean drinking plain water is enough? Not always – and especially not when you need to rehydrate quickly. During physical activity, exercise, strenuous work or extreme climatic conditions such as heat, the body can lose several litres of water. And sweat doesn't just carry away fluid, but also important electrolytes, minerals and trace elements, which the body needs to carry out its vital functions optimally. Thanks to the composition of their ingredients, slightly hypotonic drinks hydrate the body faster and restore the balance between salts and fluid. Which leaves the question: why only slightly hypotonic? Wouldn't extremely hypotonic be even better?

No, quite the opposite. If a drink is too strongly hypotonic, its sugar and salt content may be too low to draw water quickly through the cell membrane of the intestinal wall. For really fast water absorption from the small intestine into the bloodstream, a certain concentration of sugar and salt is essential. So well-dosed, slightly hypotonic drinks quickly top up your fluid balance and supply your body with important electrolytes and energy in the form of a little sugar. As with almost everything: it's all in the mix.