ISLAMABAD, March 27 (ONLINE): 2023 was the hottest year on record for planet Earth, and by the middle of the 21st century, the U.S. will experience 27\u201350 days of temperatures exceeding 90 degrees each year.
\nProlonged heat exposure may lead to heat-related illnesses with complications such as increased risk for heart disease.
\nA new study reports that high heat exposure may harm the body\u2019s immune system and increase inflammation, potentially harming a person\u2019s cardiovascular health.<\/p>\n
Scientists reported that 2023 was the warmest year on record for planet Earth, and the world\u2019s median temperature is increasing much more rapidly than it was at the start of the 20th century.<\/p>\n
If this warming trend continues, experts believe that by the middle of the 21st century, the United States will experience between 27 to 50 days of over 90 degrees each year.<\/p>\n
Almost 33% of working adults in the U.S. have a job where they are regularly exposed to the outdoors, including heat.<\/p>\n
In 2020, the U.S. Bureau of Labor Statistics reported about 2,330 cases of illness or injury caused by heat exposure. And each year, about 40 working adults die from extreme heat exposure.<\/p>\n
Prolonged exposure to high heat can lead to several heat-related illnessesTrusted Source, including:<\/p>\n
heatstroke
\nheat exhaustion
\nheat cramps
\nheat headaches
\nheat rash
\nsunburn
\n\u201cAdditionally, exposure to heat can also lead to further complications. For example, heat can negatively impact pre-existing cardiovascular diseaseTrusted Source.\u201d<\/p>\n
A new study reports that high heat exposure may harm the body\u2019s immune system and increase inflammation, potentially harming a person\u2019s cardiovascular health.<\/p>\n
The findings were recently presented by University of Louisville researchers at the American Heart Association\u2019s Epidemiology and Prevention\u00a6Lifestyle and Cardiometabolic Scientific Sessions 2024Trusted Source. The study results have yet to be published in a peer-reviewed journal.<\/p>\n
How does extreme heat affect the heart?
\nLead study author Dr. Daniel W. Riggs, assistant professor of medicine in the Christina Lee Brown Envirome Institute at the University of Louisville explained that heat exposure is an important yet underappreciated risk factor contributing to heart disease.<\/p>\n
\u201cIn the context of warming global temperatures the frequency of extreme temperature events is increasing and will continue to negatively impact population health,\u201d Dr. Riggs told Medical News Today.<\/p>\n
\u201cA better understanding of the effects of heat on health, including heart health, is necessary to develop evidence-based approaches to help mitigate and prevent future climate-related impacts on health and well-being.\u201d<\/p>\n
\u201cAlthough the link between cardiovascular disease and exposure to high heat is well established, the mechanisms and exposure pathways that promote the development of cardiovascular disease are complex and require more research. Therefore, our interest was to try to develop a better understanding of how exposure to high temperatures may contribute to immune-inflammatory activation.\u201d<\/p>\n
\u2014 Dr. Daniel W. Riggs, lead study author<\/p>\n
Analyzing the effects of temperature on cellular function
\nFor this study, Dr. Riggs and his team recruited 624 adults with an average age of 49.5 years. More than half of the participants were women, and 77% identified as white.<\/p>\n
Study participants visited study sites in the Louisville, KY area during the summer months, with each day having a median temperature of 76 degrees Fahrenheit.<\/p>\n
Researchers took blood samples from study participants, which were analyzed for cytokineTrusted Source levels linked to inflammation as well as the levels of several types of white blood cellsTrusted Source, including monocytesTrusted Source, eosinophilsTrusted Source, natural killer cellsTrusted Source, and B cellsTrusted Source.<\/p>\n
Using the blood test data, scientists then looked for associations between what was found in the blood to environmental heat levels, including the Universal Thermal Climate Index (UTCI) that day.<\/p>\n
The UTCI factors in temperature, humidity, and ultraviolet radiation levels.<\/p>\n
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Hotter temps drive inflammation
\nAt the study\u2019s conclusion, researchers found that for every five-degree increase in UTCI, there was also an increase in levels of key markers of inflammation in participants\u2019 blood samples.<\/p>\n
\u201cPrevious research has established a relationship between higher temperatures and an increase in inflammatory markers,\u201d Dr. Riggs explained. \u201cHowever, previous studies have primarily focused on ambient temperature and a limited number of inflammatory markers.\u201d<\/p>\n
\u201cThe objective of our study was to assess heat exposure using more physiologically relevant markers of heat, such as the UTCI and a larger panel of inflammatory and immune markers, with the goal of getting a more complete and accurate picture of the relationship between heat and inflammation.\u201d<\/p>\n
\u2014 Dr. Daniel W. Riggs, lead study author<\/p>\n
\u201cParticipants in our study were only exposed to moderate levels of heat, and we were surprised to find that these moderate levels were related to a variety of markers reflective of changes to inflammation, and innate and adaptive immune responses,\u201d Dr. Riggs noted.<\/p>\n
Effects of heat stress on the immune response
\nThis study also found that study participants experienced a decrease in B cells, which researchers say also indicates a lowering of the capabilities of the body\u2019s immune system.<\/p>\n
\u201cTemperature and humidity are known to be important environmental drivers of infectious, airborne disease transmission,\u201d Dr. Riggs said.<\/p>\n
\u201cThis could suggest that not only are people at higher risk of exposure to infectious disease during high temperatures, but they could also be more vulnerable to disease or inflammation.\u201d<\/p>\n
\u201cDysregulation of the immune system and inflammatory pathways are known to be a leading mechanism in many types of cardiovascular disease,\u201d he continued.<\/p>\n
\u201cOur findings suggest that heat exposure could be contributing to these pathways that ultimately lead to greater risk of cardiovascular disease.\u201d<\/p>\n
More research on heat exposure and inflammation needed
\nAfter reviewing this study, Dr. Justin Lee, an interventional cardiologist at Hackensack University Medical Center in New Jersey told MNT he felt the authors propose an interesting hypothesis that may warrant further research with better randomization and statistical analysis.<\/p>\n
\u201cInteresting hypothesis; however, there are much stronger cardiovascular disease risk factors \u2014 i.e., cigarette smoking, obesity, hypertension, diabetes, high cholesterol, family history \u2014 that have proven evidence with robust cause and effect relationship,\u201d Dr. Lee explained.<\/p>\n
\u201cIt does not appear that the authors in the study conduct thorough sample analysis and propensity matching to ensure true randomization of the subjects. Hence, the results are not immune to bias and confounders.\u201d<\/p>\n
MNT also spoke with Dr. Cheng-Han Chen, a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, about this study.<\/p>\n
\u201cWe have known for a long time that heat stress has negative effects on someone\u2019s health, including cardiovascular health,\u201d Dr. Chen said.<\/p>\n
\u201cWe\u2019ve also known that inflammation in the body also has effects on cardiovascular health. This study is useful because it directly ties changes in inflammatory markers in the bloodstream of patients in response to these short-term heat stress situations. So it makes sense that that would be so, but it\u2019s good to have the data showing this.\u201d<\/p>\n
\u2014 Dr. Cheng-Han Chen, cardiologist<\/p>\n","protected":false},"excerpt":{"rendered":"
ISLAMABAD, March 27 (ONLINE): 2023 was the hottest year on record for planet Earth, and by the middle of the 21st century, the U.S. will experience 27\u201350 days of temperatures exceeding 90 degrees each year. Prolonged heat exposure may lead to heat-related illnesses with complications […]<\/p>\n
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