Smoking :-
The coronary arteries inside us are responsible for supplying our heart muscles with O₂ rich blood. When people smoke, plaque builds up in the arteries & the O₂ rich blood will not get supplied to the hear muscles causing atherosclerosis / coronary heart disease.
Unbalanced Diet :-
Eating an unhealthy diet which is high in cholesterol & fats also causes atherosclerosis (coronary heart disease). Too much salt in the diet can also raise blood pressure which is another factor responsible for this disease.
Unhealthy Lifestyle :-
Unhealthy lifestyles like not exercising at all & being obese lead to atherosclerosis (coronary heart disease).
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Hope it helps ⚜