With or without carbon dioxide, water or iso-drink, only when thirsty or before …? There are many myths circulating about the correct drinking behavior. What is true – and what is not?
1. “In summer it must be three liters of liquid a day”
This tip is repeated like a mantra, but it is not always true, says Joachim Latsch, Professor of Preventive and Exercise Medicine at the Fresenius University in Cologne.
“If I drive to work in an air-conditioned car and then spend eight hours at the air-conditioned workplace, I certainly don’t need three liters of liquid on hot days, because that much doesn’t evaporate.” In other words: the amount of water you drink depends not only on the outside temperature, but also on other aspects – how much do I sweat, how much do I move? A marathon runner probably needs more than three liters, an office worker might get by on one and a half liters.
However, it should not be less than this minimum daily amount, as the body needs fluid for all metabolic processes. In addition, ideally, you should take in around 900 milliliters of water through moist foods such as cucumber or melon, advises the German Nutrition Society. Surprisingly, even bananas consist of 75 percent water, lean beef 72 percent and rye bread still 40 percent.
2. “Anyone who sweats a lot needs a drink with magnesium, otherwise there is a risk of cramps”
“Basically, an incipient tendency to cramp can indicate dehydration,” says expert Latsch. Adding more fluids is always a good idea if you sweat. Whether with or without magnesium, the sports doctor considers that to be irrelevant at first. Because a magnesium deficiency does not represent an acutely threatening situation. Much more important is the supply of table salt in the event of impending dehydration via sodium-containing liquids, otherwise the mineral balance in the blood can become imbalanced and thus cause circulatory problems. Incidentally, drinks containing magnesium do not act suddenly against cramps, the effect only sets in over the long term.
3. “It is enough to drink only when you feel thirsty”
“On an average day when there is no great stress, I would say: Yes,” confirms nutritionist Günter Wagner from the German Institute for Sports Nutrition in Bad Nauheim (his book: “Drink yourself fit”, pala Verlag). “However, only on the condition that someone has a good sense of their own feeling of thirst and recognizes early signals.” However, if there are particular athletic or intellectual challenges, the expert recommends drinking regularly before you feel thirsty. This avoids the onset of a lack of water, which can have a minor impact on physical and mental performance.
“Studies have shown that even a fluid deficit of 0.5 percent of body weight slows the speed of information processing in the brain,” says Wagner. On a normal working day, you are right with a glass of water or fruit spritzer every one and a half to two hours. During sport, depending on the amount of sweat, 150 to 300 milliliters of fluid can be used every 15 to 30 minutes.
4. “Carbon dioxide is unhealthy”
You can not say it like that. “The molecule carbon dioxide, from which carbonic acid is produced in connection with water, occurs naturally in the body and is involved in many processes. It does not harm us,” explains Joachim Latsch. “However, still water is easier on the stomach and can be drunk faster.” Carbon dioxide can lead to stomach pains, especially in sensitive people, for example when cycling when you sit in a hunched posture. In the worst case, a quick amount of soda can even lead to vomiting.
5. “You shouldn’t drink anything cold when it’s hot”
One hears again and again, but an iced drink is often just too tempting. Günter Wagner thinks that’s okay in principle. Limitation: “The body does not have to warm up lukewarm drinks first, we can ingest a larger amount of them and have a better cooling effect for the body overall.” Joachim Latsch also warns sensitive stomachs of possible problems. “The stomach lining reacts to the strong cold stimulus with a small shock.” Since the stomach is supplied with a large number of nerves, nausea or pain may occur.
6. “Water can’t go bad”
That’s not true. Both tap water and water from the bottle can be colonized with germs and cause gastrointestinal problems. “The problem with tap water: It was checked in the waterworks, but not at the domestic tap. The last few meters from the waterworks to the consumer are generally not checked. For example, the aerator on the tap is a perfect breeding ground for mold spores and bacteria that then get into the water can ignore “, explains Günter Wagner. Germs also get into it when drinking from the bottle. If the water bottle is also in the sun, potential pathogens multiply quickly. However, unopened and chilled, water can be kept for a very long time.
7. “Alcohol-free beer is the perfect sports drink”
Not a myth, but a clear yes to the cool blonde after training – of course without alcohol. “Alcohol-free beer is absolutely recommended as a sports drink, as it supports regeneration,” says nutritionist Wagner. On the one hand, it is one of the isotonic drinks: The number of osmotically active particles, such as minerals and vitamins, corresponds to the number in the human blood, so it can be absorbed particularly quickly.
“On the other hand, there is a lot of potassium in it, which supports the storage of carbohydrates in the muscle cells,” adds Günter Wagner. B vitamins also reduce tiredness and exhaustion during the regeneration phase. And a study showed that alcohol-free beer can even reduce the susceptibility to infections after exercise, presumably because of the phytochemicals.
8. “The color of the urine tells you whether you have drunk enough”
“In fact, the color of the urine in healthy people is a helpful indicator for recognizing adequate hydration,” confirms Joachim Latsch. Rule of thumb: the brighter the better. However, some foods, such as beetroot, can also distort the color impression. “For example, when taking high doses of vitamin C, the urine appears noticeably light yellow,” says the doctor. As a precaution, you should always have any unusual discoloration or cloudiness clarified by a doctor.
9. “You can’t drink too much, that’s eliminated”
Sounds crazy, but drinking too much can actually lead to “water poisoning”. “Normally, excess fluid in the body is regulated very quickly via urine production and excretion,” says Günter Wagner. In extreme situations such as a triathlon, however, it has happened that athletes have consumed huge amounts of low-sodium drinks in a few hours. “Then the blood becomes thinner and the electrolyte balance can derail. This leads to hyponatremia. In the worst case, there is a risk of edema and organ failure.” There were even deaths, for example in the USA after a water-drinking competition or most recently in 2015 at an Ironman event in Frankfurt am Main.
10. “Coffee removes water from the body”
That was the common doctrine for a long time, but now we know: “If you regularly drink coffee, the original dehydrating effect no longer occurs. The body learns to suppress the effect,” explains Günter Wagner. Therefore you can add moderate amounts, about three to four cups a day, to your drinking balance.
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