Many people have the impression that summer is the season when you get sick the most. In reality, experts say, high temperatures can affect the functioning of the immune system and promote the appearance of infections or other health problems. Fortunately, there are simple measures that can reduce these risks.
Many people believe that periods of changeable weather, cold or strong wind favor illness, while summer is a season in which the risk of infection decreases considerably. High temperatures often create the impression that colds and flu are no longer a threat.
However, experts point out that things are not that simple. Extreme heat and heat waves can affect the functioning of the immune system and make the body more vulnerable to infections and other health problems. Fortunately, research shows that there are effective measures by which these effects can be prevented or reduced.
High summer temperatures cause inflammation
There are several important studies looking at the effects of high temperatures on health, especially on the immune system. Researchers have identified a link between heatwave episodes and certain reactions in the body, including changes in the levels of certain blood cells and inflammatory markers.
One of the largest studies on this topic was presented at the “Epidemiology, Prevention, Lifestyle and Cardiometabolic Health” conference organized by the American Heart Association in Chicago. Although previous research has suggested a link between temperature and inflammation in the body, this is considered one of the most extensive studies to date.
The research team analyzed blood samples taken from 624 participants between the ages of 20 and 70. Each volunteer provided a sample during the summers of 2018 and 2019. The scientists measured the concentrations of 11 types of cytokines and the levels of nine categories of immune cells in each sample.
At the same time, the weather conditions on the day of harvest were analyzed using the Universal Thermal Climate Index (UTCI), an indicator that evaluates the combined effect of temperature, humidity and wind speed on the human body. During the studied period, the average UTCI value was approximately 26 degrees Celsius.
The blood test results were correlated with weather data, and the researchers statistically adjusted the results for factors such as gender, age, race and education level of the participants.
The findings showed that during periods of higher temperatures, especially when the heat index exceeded the equivalent of about 25 degrees Celsius, the levels of some inflammatory cytokines increased significantly, suggesting a stronger inflammatory response of the body. At the same time, the researchers observed higher values of monocytes, a type of white blood cell involved in inflammatory processes and defense against pathogens.
The study also revealed a decrease in the level of B lymphocytes, cells of the immune system that help produce antibodies and fight infections.
These results suggest that high temperatures can promote an inflammatory response and influence the functioning of the immune system. Persistent inflammation is associated with a higher risk of cardiovascular disease and is one of the mechanisms by which the body responds to infection or injury.
In short, research indicates that heatwave episodes not only stress the cardiovascular system, but can also alter the activity of the immune system, increasing markers of inflammation and reducing some of the cells involved in the body’s defenses. This phenomenon could explain, at least in part, why periods of extreme temperatures are associated with a higher risk of health problems.
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Heat changes the composition of the blood
The effects of heatwaves and very high temperatures in general are not limited to inflammation and damage to the immune system. Other studies show that prolonged exposure to heat can produce real and measurable changes in blood composition, even in perfectly healthy people. These changes can create the impression of a reduced oxygen-carrying capacity, although the total number of red blood cells does not actually decrease.
A study published in Medical Aspects of Harsh Environments shows that the body’s adaptation to high temperatures causes an increase in plasma volume, a protective mechanism designed to maintain blood pressure and facilitate body cooling during heat stress.
Other research indicates that hot weather stimulates the release of stress hormones, such as cortisol, which can reduce the activity of certain immune cells and decrease the body’s ability to respond effectively to pathogens.
In addition, high temperatures promote oxidative stress, a process that can affect the integrity of the protective barrier of the gastrointestinal tract and make it more permeable to bacteria and toxins. Although respiratory infections are more common in the cold season, the thermal stress caused by the heat wave can increase the body’s vulnerability, including digestive infections.
In short, research suggests that prolonged exposure to heat can impair immune system function, promote inflammation, and alter certain characteristics of the blood and gut barrier. Dehydration and lack of adequate recovery can amplify these effects and increase the risk of health problems.
How can we protect our body from the effects of heat
The good news is that doctors have developed a series of simple recommendations to protect the body from the effects of heat stress during the summer. The most important measures are effective cooling of the body and maintaining constant hydration.
Specialists recommend avoiding exposure to the sun during peak hours, wearing light, light-colored clothing and spending time in air-conditioned spaces whenever possible, as these are more effective than simply using fans.
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Hydration plays an essential role. Doctors recommend drinking at least 2-3 liters of water a day, without waiting for the sensation of thirst to appear. During periods of extreme temperatures, the body loses not only water but also important electrolytes through sweat. Therefore, drinking electrolyte drinks or foods rich in sodium, potassium and magnesium can be helpful.
At the same time, it is indicated to limit the consumption of alcohol and drinks with a high caffeine content, because they can promote dehydration.
Equally important is the environment in which we spend our time. During the day, windows should be kept closed and protected with blinds, curtains or shutters to reduce heating of the home. Airing is recommended during the night and early morning when temperatures are lower.
Attire can also make a difference. Light, loose and light-colored clothes help the body to eliminate heat more efficiently. A wide-brimmed hat and sunglasses with UV protection are recommended when in the sun.
Specialists also advise to limit intense physical activities outdoors and to avoid direct exposure to the sun between 11:00 a.m. and 5:00 p.m., when solar radiation is usually the strongest.
For the rapid decrease in body temperature, cool showers or baths are recommended, as well as the application of wet and cold towels on the neck, underarms and wrists, areas that contribute to the rapid cooling of the body.
