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Sports drinks have become widely popular and are even often consumed in everyday life. However, depending on their contents, sports drinks can also cause discomfort.

It used to be isotonic drinks that were popular with athletes, with recipes aiming to replenish the fluids and electrolytes lost during training. Nowadays, there are numerous specialist sports and fitness drinks that contain many other ingredients alongside carbohydrates and electrolytes. The most common ingredients include artificial sweeteners and flavourings, added vitamins and minerals as well as caffeine.

Sports drinks have also long since been consumed outside of sport, as a ‘healthy’ alternative to soft drinks. This is due to a greater health awareness, with consumers considering that they are doing something good for their health.

But beware: not everyone tolerates these drinks the same. Certain ingredients can actually cause issues, especially in an athletic context, which places extra demands on the body and its digestive system. This often depends on the quantity of added ingredients and one's individual sensibility to them. The following five ingredients are most likely to cause digestive issues:

1. Artificial sweeteners
   Artificial sweeteners, which are used to replace sugar in many food and drink products, can trigger intolerance reactions in certain people. These reactions vary in their nature and severity, and can be provoked by various mechanisms. It is also known that artificial sweeteners can change the composition of the intestinal flora and alter gut health as a result, which can aggravate intolerances.
2. Fructose
   Fructose is found in many sports drinks and gels as it uses two types of carbohydrate transport channels (glucose and fructose transporters). This enables a high supply of carbohydrates (e.g. 90 grams of carbohydrates per hour) with minimal risk of gastrointestinal problems. However, some people can be sensitive to fructose and develop intolerances.
3. Added vitamins and minerals
   Added vitamins and minerals in drinks may be beneficial for some people, but they can also lead to intolerances and gastrointestinal issues for others. Overdosing of vitamins and minerals is also a common problem. In excessive amounts, these ingredients can even be toxic and cause health issues.
4. Colourings and preservatives
   Preservatives and colourings are frequently used in food and drink products to increase their shelf life and improve their appearance. Some people can have allergic reactions to certain additives such as sulphites. Other people, while not allergic, can still experience discomfort.
5. Osmolality
   The best sports drinks have a hypotonic or isotonic osmolality. However, drinks with lots of additives such as excessive vitamins and minerals are often hypertonic, and are therefore less suitable for intensive exercise, as they hinder fluid intake.

What can we learn from this?

Sports drinks are high-energy drinks containing a certain amount of carbohydrates and added salt. The more substances added to a drink – such as preservatives, artificial sweeteners, flavourings or excessive vitamins and minerals – the higher the risk of intolerance.

It's therefore worth checking the list of added ingredients and questioning the purpose of individual ingredients, particularly if you generally have a healthy diet. It's also important to try out individual sports drinks in training before using them in competition. A self-mixed sports drink is one way to avoid intolerances. For this, opt for maltodextrin, salt and a form of sugar. The mix should be tailored to your individual needs such as the length of the workout, drink quantity and expected salt loss.