Tobacco harm is one of the world’s most serious public health problems, and tobacco control has become an important measure to prevent disease. China is currently the world’s largest consumer and victim of tobacco, with more than 300 million smokers and another 740 million non-smokers suffering from secondhand smoke. The number of deaths due to smoking-related diseases exceeds 1 million each year, and the figures are alarming. The general public’s knowledge of the dangers of smoking tends to focus on the lungs and heart. For example, lung cancer, chronic obstructive pulmonary disease, coronary heart disease and atherosclerosis. But did you know that smoking is very closely related to osteoporosis? Many smokers do not quit smoking when they take calcium supplements, and many women who suffer from secondhand smoke take calcium supplements every day but still have little success, and the reason for this is the effect of tobacco. So what is the relationship between tobacco and osteoporosis? First of all, osteoporosis may be due to a variety of causes of bone density and bone quality decline, bone microstructure damage, resulting in increased bone fragility. Osteoporosis is subdivided into three types: postmenopausal osteoporosis, senile osteoporosis and idiopathic osteoporosis. Postmenopausal osteoporosis generally occurs in women within 5-10 years after menopause; senile osteoporosis generally refers to osteoporosis occurring in the elderly after the age of 70; and idiopathic osteoporosis mainly occurs in adolescents, the cause of which is still unknown. In China, osteoporosis occurs at an earlier age than people think, even from the age of 20 or 30. The effect of tobacco on bone density is mainly manifested in the nicotine in tobacco that affects calcium absorption, nicotine inhibits osteoblasts and stimulates the activity of osteoclasts, which ultimately leads to a decrease in bone density and the formation of osteoporosis. Studies have shown that the longer you smoke, the more severe the bone loss and the more pronounced the osteoporosis. In a Korean study, postmenopausal women who never smoked had a positive correlation between the degree of osteoporosis and their exposure to secondhand smoke. Therefore, both smokers and those exposed to secondhand smoke should take appropriate measures if they develop symptoms of osteoporosis or if tests reveal a decrease in density, the most important of which is to quit smoking and stay away from secondhand smoke exposure.