Which of the following is a recognized risk factor for osteoporosis?

• A. Smoking
• B. Light physical activity
• C. Adequate calcium intake
• D. High vitamin D intake

Answer: (A)

Smoking is a recognized risk factor for osteoporosis because it disrupts bone remodeling in several ways. It lowers estrogen levels (which protects bone in both sexes but especially after menopause), increases bone resorption, reduces calcium absorption from the gut, and can impair blood flow to bone tissue. These effects collectively lower bone mineral density and raise the chance of fractures.

In contrast, adequate calcium and vitamin D intake support bone health, helping maintain density and strength, and regular weight-bearing activity strengthens bones. Low activity is not shown here as a protective factor, and smoking stands out as the factor that increases osteoporosis risk.