How is water digested

Water absorption in the body

The faster the body can absorb the water, the better

During intense endurance activities, such as during a competition, the rate of water loss through sweating is great and the time available for the re-absorption of water is very short. It is therefore important that the drink is absorbed as quickly as possible so that further dehydration is contained during the competition or training.

The body absorbs water in the small intestine. Drinks ingested must first pass through the stomach before water absorption can begin. That said, a drink can only be effective if it moves quickly from the stomach to the intestines. The most important factor affecting gastric emptying is the carbohydrate content. Studies have clearly shown that water absorption occurs very slowly when pure water is fed into the intestine. The addition of glucose, which is actively and relatively quickly absorbed by the cells in the intestinal wall, and sodium, which is transported along with glucose, increases the rate of water absorption. Adding sodium without glucose, on the other hand, has hardly any effect.

It all depends on the right composition

If too many carbohydrates and / or minerals are added, water flows into the bowel in the opposite direction of the blood. The osmolality (measure of the pressure ratios between liquids) of the drink is too high. This reduces the speed at which the fluid is effectively transferred from the intestine to the blood (absorption). This is anything but desirable for endurance athletes who lose fluid with sweat and thus impair the ability of their blood to flow.

With the exception of sodium, electrolytes such as magnesium, potassium, and chloride have no effect on this absorption-stimulating process. The electrolyte losses through sweating during exercise are relatively small and a mineral intake in an order of magnitude that exceeds the loss has no detectable effects on fluid intake and performance. It is therefore advisable not to consume minerals in amounts that exceed the sweat loss.

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