How to avoid dehydration and heat stroke in summer

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This can happen to anyone, young people, who perhaps spend a lot of time outdoors playing sports or under the sun to tan, and older people, who tend to drink less, not feeling thirsty, and easily become dehydrated.

How can we protect ourselves?

There are some basic rules, such as

• avoid going out during the hottest hours
• Choose light-colored clothing, made of natural fabric and loose, not tight, which allows the body to sweat
• Include fresh fruit and vegetables, rich in water, in our diet
• Stay hydrated

In reality, of all the points listed, the last one is probably the most critical. How many of us feel thirsty, indicating that we are already dehydrated?

Hence the importance of understanding what the best behaviors are to combat dehydration and heat stroke, whether to choose hot or cold drinks, whether to drink them all together or in small sips, whether coffee should be limited...

In short, there are so many questions and today we will try to answer them all, based, as always, on the most important scientific research.

1 Hot drink or cold drink?

What is better in summer, a nice iced tea or herbal tea? Surely at this point you will all have thought about iced tea, yet... according to science it is not a good choice.

But let's delve deeper into it.

• The first piece of information is that if you are a sportsman or otherwise expose yourself to heat, the drink for you is a hot herbal tea, which helps you cool your body more quickly. This emerges from research published in the journal Acta Physiologica by a Canadian team [1].

The researchers recruited 9 adults who were asked to ride a bicycle for 75 minutes in an environment with a temperature between 23 and 24° C.

Some volunteers received a very cold drink, at 1.5° C, to be taken 5 minutes before the start of the sporting activity, and then after 15, 30 and 45 minutes.

Other volunteers were asked to drink drinks at 10° C, 37° C and 50° C, in the same way as the first group.

The volunteers were connected to sensors to measure sweating and body heat.

What emerged was that it was possible to accumulate less heat, and therefore counteract the overheating of the body and therefore heat stroke, by drinking the hotter drink. This is because the drink introduces more heat but stimulates more sweating.

However, you need to be able to sweat. This does not apply in very high humidity conditions such as a sauna or immersed in water.

• The second piece of information is that if you are already dehydrated the best way to rehydrate is to drink liquids at a temperature lower than room temperature but not cold, at 16° C. This emerges from research published in the International Journal of Clinical and Experimental Medicine and conducted by an Iranian team [2]

What the research has tested is, in fact, how we can take action in the best possible way when we are already in a condition in which we have not drunk enough and are experiencing the first symptoms of dehydration.

The study is small, involving only 6 people, but it is noteworthy. In fact, it allowed us to observe that 16° C is the optimal temperature for drinking water when we need to integrate lost fluids. This temperature is in fact associated with a greater intake of liquids and less sweating, allowing better and more effective hydration compared to very cold drinks, around 5° C, or very hot drinks, above 50° C.

2 Why it is important to drink in small sips

We have seen the optimal temperature of water or other liquid to rehydrate us if dehydrated or avoid heat stroke.

But how should water be drunk? All together, as we often see, in small sips but regularly or does the way of drinking not matter?

Of course, drinking is always important, however you do it, but drinking in small sips and regularly is the best way. In fact, drinking large quantities of liquids all at once is not good for your health, since:

• it increases blood pressure, both in healthy and hypertensive people. To give an idea, a study observed that quickly drinking 500 ml of water led to an increase, albeit temporary, in blood pressure, both systolic and diastolic, both in those with normal and raised blood pressure, even by 20 mmHg [3]
• The body is not given time to assimilate water. The high quantity of liquids immediately triggers the disposal processes and water is eliminated quickly, not allowing correct hydration of the body [4]

Hence the need to drink in small sips but constantly.

3 When drinking dehydrates…

Sometimes drinking… dehydrates, thus causing us to obtain the opposite effect to what we expected. But what are dehydrating drinks? Here they are:

• Sugary drinks worsen dehydration [5]
• Alcohols, stimulate diuresis and worsen dehydration [6]
• Excess tea and coffee. Instead, these drinks, when drunk in moderation, 4-6 cups of tea and up to 3 cups of coffee per day, have been shown to have the same hydration capacity as water [7][8]

4 What we learned

Therefore, no ice tea, in any case.

On hot days the best way to rehydrate when we have sweated a lot is to drink cool but not iced liquids, around 16° C.

If, however, we are sports enthusiasts or simply don't want to give up a short walk on a hot day, hot drinks are our allies to avoid accumulating too much heat and risking heat stroke.

Then, as we have seen, it is better to avoid drinking a lot of liquids all at once but to sip them throughout the day.

Also avoid hydrating with sugary drinks and alcohol or drinking excessive tea or coffee. These drinks can make dehydration worse.

5 The symptoms of dehydration

This article is dedicated to how to combat dehydration and heat stroke.

But how do we understand that we are dehydrated? What are the symptoms of dehydration? Recognizing them in time, in fact, is of crucial importance.

Let's see the main symptoms of dehydration, as we will see, some are easily attributable to dehydration, others less so, which is why it is important to be aware of them [9]

• Thirst and dry mouth. We feel thirsty when we are already dehydrated so it is important to never feel thirsty
• Dry skin
• Dark urine, this is a good way to orient ourselves as to whether we are drinking enough or not. The urine should be as clear as possible, if it starts to get darker it is time to take action. In fact, it is not possible to establish how much water a person should drink, it is a value that changes based on age, lifestyle and the medicines taken. But the color of urine is considered an always valid parameter to establish whether we are drinking enough
• Headache
• Tiredness
• Fast breathing
• Mild mental confusion

6 Symptoms of heat stroke

The body tries to maintain its internal temperature at around 37° C. Sweating is the ally to regulate body temperature and prevent it from increasing.

Excessive heat, high humidity or very intense physical activity under the sun can mess up our body cooling system, especially if we aren't drinking enough.

Here the sweat is not enough to cool the body and the heat accumulates inside causing heat stroke, a condition in which the body temperature can reach 40° C.

In this case, it is necessary to intervene quickly to lower the body temperature, take the person immediately to cool, shaded areas, make cold compresses on some areas of the body such as the forehead, armpits and groin area, ask to drink liquids in small sips, if this is possible, and promptly contact a doctor [10].

But how do we recognize heat stroke? Here are the main symptoms of heat stroke [11]:

• Red and hot skin
• Dizziness
• Mental confusion and weakness
• Headache
• Nausea or vomiting
• Rapid breathing and heart rate
• In more serious cases even fainting