With the arrival of the hot season, a wealth of well-intentioned advice circulates each year on how best to combat the summer heat. However, not all of these recommendations, often passed on by word of mouth or disseminated in popular media, can actually be backed up by scientific facts.
The Association for Consumer Information (VKI) has therefore subjected a number of these common summer myths to a comprehensive fact check to provide clarity and protect consumers from misconceptions. From the question of the ideal beverage temperature to the effects of spicy foods to the supposed protective effect of dietary supplements – the results surprise some and offer sound guidance for healthy behavior on hot days.
Isotonic drinks: When are they really necessary?
A widespread belief is that isotonic drinks are essential in extreme heat and increased sweating to balance the body's fluid and mineral balance. However, nutritionist Teresa Bauer from the VKI (Association of German Nutritionists) clarifies: "For everyday life and normal physical activity – even in sweaty summer temperatures – the tried-and-tested classics of water, mineral water, and unsweetened tea are sufficient." These drinks provide sufficient fluid and the necessary electrolytes for the average person without placing unnecessary strain on the body.
Isotonic drinks only show their strengths when intense physical exertion that lasts longer than an hour. This includes, for example, extended hikes, long bike rides, or very demanding sporting activities. Under these conditions, the body not only loses large amounts of fluid through increased sweating, but also significant amounts of important minerals such as sodium, potassium, calcium, and magnesium. "Isotonic drinks can help quickly compensate for this loss," says Teresa Bauer. The purpose of these drinks is to quickly replace lost electrolytes and carbohydrates in order to maintain performance and prevent dehydration and electrolyte imbalances.
However, it's important to note that expensive, commercially available sports drinks aren't absolutely necessary. Teresa Bauer recommends a simple and inexpensive home recipe: "A simple home recipe consists of one part apple juice, two to three parts water, and a pinch of salt. The sugar in apple juice provides quick energy without putting a strain on the stomach." This homemade drink serves the same purpose as commercial products, but is significantly less expensive and free of unnecessary additives. The mixture of carbohydrates (sugar from apple juice) and electrolytes (salt) ensures rapid absorption and utilization by the body.
Drink temperature and food selection: What really cools?
The question of the ideal temperature for drinks on hot days often leads to conflicting opinions. While many people instinctively reach for ice-cold drinks to cool off, the VKI advises caution. "Cool drinks can provide pleasant refreshment – but ice-cold versions should be avoided," explains Teresa Bauer. The reason for this is that extremely cold drinks can trigger stomach cramps or circulatory problems, as the body has to expend additional energy to warm the liquid to body temperature. This can place additional strain on the circulatory system instead of relieving it.
Alcoholic beverages should also be consumed with caution in hot weather. They place a significant strain on the circulatory system and, as always, are only recommended in moderation. Alcohol has a diuretic effect and can increase the risk of dehydration in high temperatures. This underscores the importance of primarily relying on non-alcoholic thirst quenchers.
The myth that hot tea is ideal on summer days because some cultures drink it in hot weather is also refuted. "Although the consumption of hot tea is culturally widespread in many countries, it is not ideal for our latitudes and summer days: Hot drinks further stimulate sweating in hot weather," says Teresa Bauer. Although this can have a cooling effect in dry climates due to evaporative cooling, additional sweating in more humid or temperate climates, such as Central Europe, simply places increased strain on the circulatory system. The expert therefore recommends: "Cool or lukewarm non-alcoholic beverages are the best choice for summer—and in extreme heat."
Another common belief is that spicy food has a cooling effect in hot weather. Capsaicin, the hot ingredient in chilies, actually stimulates sweating. "This generally has a cooling effect, but additional sweating in high outside temperatures also puts additional strain on the circulatory system," explains Teresa Bauer. While in some cultures, particularly in hot and dry regions, spicy foods traditionally serve to cool the body through increased sweating and thus utilize evaporative cooling, this is less beneficial in other climates. "Those who like spicy food don't have to forgo it in the summer, but should pay attention to their body's signals. And people with sensitive stomachs are generally well advised to enjoy spicy foods only in moderation." Excessive consumption could lead to stomach upset or discomfort, especially if the circulatory system is under heat-related strain.
Sun protection: Capsules instead of cream? A dangerous misconception
A particularly dangerous myth concerns sun protection through dietary supplements. Beta-carotene capsules are often advertised as natural sunscreen or as a means of supporting a "healthy tan." However, the advertised protection against UV rays is not sufficiently scientifically proven and can lead to a false sense of security.
With high intake, an excess of carotenoids can accumulate in the liver, fatty tissue, and skin, leading to an orange to brownish skin discoloration. "However, this color change has nothing to do with a true summer tan, which is caused by the production of the skin pigment melanin," emphasizes Teresa Bauer. Melanin is the natural pigment the skin produces in response to UV radiation to protect itself. The discoloration caused by beta-carotene does not provide this protection.
"Dietary supplements such as beta-carotene capsules do not offer reliable protection against UV radiation," warns the VKI expert. They can in no way replace the need for sunscreen. The best and only scientifically based protection against the harmful effects of UV radiation remains unchanged: "Apply sunscreen generously, reapply regularly, and avoid direct sunlight during its most intense hours if possible." This means seeking shade or wearing protective clothing, especially between 11 a.m. and 15 p.m., when the sun's rays are at their most intense. The recommendation to use sufficient sunscreen with the appropriate SPF, and to reapply it after perspiration or after a certain period of time, remains the most effective method to avoid skin damage, sunburn, and long-term risks. The VKI therefore appeals to consumers not to be deceived by misleading advertising claims and to rely on proven protective measures.