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The miracle food for summer is… agua. We could end here and it would probably be the shortest article published in The Conversation. But we are scientists and we must justify our claims.
The increase in outside temperature that occurs in summer (and in springs as hot as this 2022 in Spain) causes an increase in body temperature. Can food help us mitigate its effects?
This regulates body temperature
In general terms, our body temperature is around 37ºC. In women, this varies slightly due to changes in the levels of progesterone and estrogen. During days 18-23 of the menstrual cycle, it is half a degree higher than during the first days.
When it’s hot, specific receptors located in the skin send information to the hypothalamus, a small region of the brain that assesses temperature.
If it is higher than normal, it will send nerve signals to the sweat glands. The goal is none other than to maintain body temperature within the normal range.
The sweat glands respond by increasing the excretion of sweat. And since the evaporation of sweat water consumes a lot of energy from our own body, it produces a cooling effect. This process depends on the humidity of the environment and the air flow: when the former is very high, evaporation is scarce, so its cooling effect is limited.
Objective: avoid dehydration
The loss of water to lower body temperature must be compensated by increasing fluid intake. Otherwise, we fall into dehydration, with significant negative consequences for our health, including death. In fact, according to estimates from the National Epidemiology Center, in the summer of 2021 there were 1,298 deaths attributable to excess temperature in Spain.
Before reaching this situation, if the loss of liquid is high, we can suffer heat exhaustion. Although body temperature is maintained, the loss of water and electrolytes can cause weakness, dizziness, nausea, and fainting.
The so-called heat stroke or sun stroke is more serious and can cause death. In this case, the body temperature does increase to 40ºC or more. The consequences can be tachycardia, headaches, hot and dry skin or even confusion, convulsions and loss of consciousness.
That means that our body has the necessary mechanisms to protect us from the heat. What is up to us is to help you by providing the water you need to be able to perform this function.
Where to get the water we lose
In addition to water, other foods rich in it can make an important contribution to the regulation of body temperature. Drinks (including milk), vegetables, fruits and vegetables are the foods that hydrate the most.
The health benefits of eating vegetables and fruits are undoubted and go beyond their water content. Increasing the intake of these foods decreases the risk of mortality and of becoming overweight or obese or gaining weight.
As for drinks, there is no common criteria. Milk and infusions are good options, as long as they are not sweet. The rest are not recommended. Juices, nectars, sugary drinks or smoothies provide free sugars, which are related to poor diet quality, obesity and the risk of contracting non-communicable diseases.
Replacing added sugars with sweeteners doesn’t seem like a good idea either. Numerous publications show negative effects on our health and, furthermore, long-term studies are lacking.
Cold or hot?
It remains for us to find out if it is preferable to take cold or hot food. There is no doubt that eating them at a low temperature has a refreshing effect that we all perceive. However, in recent years, new studies have suggested that perhaps hot foods are also a good option.
Before going into details, it must be said that the investigations are focused on sports. This is so because heat negatively affects sports performance, especially in aerobic exercises such as running, swimming, walking or cycling.
Well, it seems clear that eating cold food involves a loss of internal heat by having to temper them until they reach body temperature. Consequently, sweating decreases because it is no longer necessary to lose so much heat.
On the contrary, the intake of hot food increases sweating. And, as we have seen, the evaporation of this sweat is what causes the loss of body heat. However, in conditions where that sweat cannot evaporate (high humidity and no air), the mechanism has limited effectiveness.
Having said all this, the question is to take these results day by day. If what we are looking for is not to sweat, the solution is to eat cold food in order to lose heat internally. If we don’t mind “sweating the fat drop” and we are able to evaporate that excretion, hot foods are an option. Of course, then it is not worth wiping the sweat.
Ana Belen Ropero Lara. Professor of Nutrition and Bromatology – Director of the BADALI project, Nutrition website. Bioengineering Institute, Miguel Hernández University
Marta Beltrá García-Calvo. Professor of Nutrition and Bromatology. Collaborator of the BADALI project, Nutrition website. Bioengineering Institute, Miguel Hernández University.
This article was originally published on The Conversation.
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