Wellness

Heart attack, stroke: the cold poses a fatal risk

Our body has incredible capacities for physiological adaptation to external variations, but our contemporary way of life pushes it to its limits, reducing the margin of safety with which evolution has endowed it. During the cold winter season, the increase in heart attacks and strokes testifies to the risk that we run from not taking care of our health throughout the year.

Our body has a tremendous ability to adapt very quickly to temperature variations, when we return for example from a destination in the sun during the cold period of the year, we can easily go from 30 oC to -10oC in a few hours. barely, without this sudden temperature change causing too much physical discomfort.

This adaptation takes place completely automatically: the body exposed to the cold will immediately seek to reduce its loss of heat by constricting the small arteries located just under the skin, a phenomenon called vasoconstriction. The blood is then less exposed to the cold, which makes the skin pale and cold, but this mechanism helps to minimize heat loss and keep the core temperature constant for the internal organs to function normally. Cold hands perhaps, but warm hearts.

Heart disease in winter not only related to the cold

Despite the effectiveness of this internal thermostat, the cold can be deadly for people who are at risk of heart disease.

Several epidemiological studies have in fact shown that myocardial infarction or cerebrovascular accidents (CVA) are more frequent during cold seasons. These cardiac events are particularly well documented during intense physical exertion in cold weather, such as shoveling heavy snow, because the sudden rise in blood pressure and rapid heart rate can then cause the rupture of atherosclerotic plaques. present on the wall of the blood vessels and thus block the arrival of oxygen to the heart or the brain. However, most heart attacks or strokes that occur in cold weather are not the result of violent physical exertion and other factors must necessarily be at play to explain this winter increase in heart disease.

The “burnt” fat ends up in the arteries and mouths

To solve this enigma, a team of Swedish and Chinese researchers looked at the potential impact of cold on the metabolism of blood lipids, the main responsible for the formation of plaques that lead to heart attacks or strokes. Using a model system that mimics the development of these plaques, they first observed that levels of bad cholesterol (LDL and VLDL) were greatly increased upon exposure to cold, resulting in a marked acceleration the development of plaques in the wall of blood vessels.

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This increase in fat would come from brown fat reserves: when exposed to cold, this adipose tissue has the particularity of “burning” fat to generate heat. This phenomenon is normally considered positive, insofar as it contributes to the maintenance of a normal weight, but it seems that a portion of the fats which are released during this lipolysis are captured by the blood vessels and can over time obstruct blood circulation.

Lifestyle and warm clothes

People who have a history of heart disease or whose lifestyle predisposes them to these diseases (sedentary lifestyle, smoking, diabetes, overweight, high blood cholesterol levels) are therefore particularly at risk of heart attack and stroke during cold seasons. For these people, adequate protection against the cold, combined with the adoption of a healthy lifestyle (diet, regular physical exercise and maintaining a healthy weight) is therefore the best way to significantly reduce the risk of these diseases. .

Source

Dong M et al. Cold exposure promotes atherosclerotic plaque growth and instability via UCP1-dependent lipolysis. Cell Metab. 18:118-29.

[HighProtein-Foods.com]

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