Overexposure to heat can cause chronic health problems

huhNational officials from the US, UK, Europe and Japan have warned residents to stay out of the sun as the Northern Hemisphere experiences some of the highest early summer temperatures on record. It is not only to prevent heatstroke, but also to prevent its long-term consequences. As climate change pushes summer temperatures even higher than normal, medical researchers are beginning to find links between long-term heat exposure and chronic health problems ranging from diabetes to kidney stones, cardiovascular disease and even obesity. “While an increased risk of heat stroke is an obvious manifestation of global warming, today climate change is causing health problems, both direct and indirect,” said Richard J. Johnson, medical professor and researcher at Anschutz Medical University of Colorado. . Campus, and one of the world’s foremost experts on the intersection of heat stress and kidney disease.

Warmer days carry an increased risk of dehydration, Johnson says, which in turn can cause cognitive dysfunction, high blood pressure, and acute kidney injury. Over time, chronically dehydrated people are less able to excrete toxins, leaving a higher concentration of salts and glucose in the kidneys and blood serum. Those substances have been linked to an increased risk of diabetes and metabolic syndrome, a medical term describing a combination of high blood sugar, high blood pressure, high cholesterol and abdominal obesity that is estimated to affect nearly a quarter of American adults. As temperatures rise, he says, it’s likely so will the incidence of metabolic diseases, along with the concomitant risk of heart attack and stroke.

Read more: What extreme heat does to the human body?

The increased development of kidney stones is another possible consequence of rising temperatures. A 2008 research paper published in the Proceedings of the National Academy of Sciences, argues that an unexpected result of global warming is the likely northward expansion of the current southeastern U.S. kidney stone belt, where heat and humidity are higher and cases are currently concentrated. The risk of developing kidney stones is exacerbated by either low fluid intake or excessive fluid loss, both of which occur with high temperatures. The paper’s authors found that, based on forecasts of climate change-induced temperature increases, the percentage of the U.S. population living in high-risk zones for kidney stones will grow from 40% in 2000 to 56% in 2050 and to 70 percent in 2000. % by 2095. Even if kidney stones do not develop, consistent exposure to high temperatures and dehydration, for example in farm workers, has been shown to cause irreversible kidney damage in some cases, as described in a 2015 case study co-authored by Johnson. and published in ScienceDirect involving sugar cane workers in El Salvador. “The kidney is very sensitive to heat stress,” Johnson says. “It is a barometer for health and climate change.”


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Johnson, author of Nature wants us to be fat: The surprising science behind why we gain weight and how to prevent and reverse it is about to publish a new paper looking at the links between dehydration and obesity, with clear implications for those living in warmer areas. “When an animal begins to develop dehydration, it triggers the production of fructose from carbohydrates,” Johnson says. The fructose stimulates the production of vasopressin, which helps to store water in the body. But vasopressin also stimulates the production of fat. Camels, he says, don’t store water in their humps, they store fat. When the fat is burned, it produces water. “Fat is used by animals for survival when water is not available,” he says. Fat production is the body’s response to — and anticipation of — dehydration.

Johnson’s hypothesis is that “climate change makes it easier to become dehydrated and warm, thereby triggering this chemical reaction so that when carbohydrates are present, it will lead to more fructose and vasopressin,” he says. “You can cause obesity in animals by making them slightly dehydrated, so there is a very strong link between dehydration, heat stress and obesity.”

Read more: What it’s like to live in one of the hottest cities in the world – where it might soon be uninhabitable

Of course, dehydration is not an inevitable consequence of hot days. It’s easy to avoid by drinking water — not sugary drinks — to stay rested and find shade. For those who work and sweat in hot conditions, this means frequent breaks and rehydration with sports drinks or electrolyte solutions to replenish potassium, sodium and other minerals lost through perspiration. “Wear a hat,” Johnson says. “Get out of the sun.” His advice sounds just like that of other health officials for a reason. Heat can be deadly. Sometimes fast — heatwaves kill more people in the U.S. every year than hurricanes, lightning, tornadoes, floods, and earthquakes combined — and sometimes slowly. “Going to an ER with heat stress increases your risk of developing chronic kidney disease later in life,” Johnson says.

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