Currently, there is no dietary supplement or general medication proven to prevent cancer for the average person. In fact, taking high-dose supplements can sometimes do more harm than good. The most effective way to lower your risk is through healthy lifestyle choices: eating a diet rich in fruits, vegetables, and whole grains, staying physically active, avoiding tobacco, and limiting alcohol. For certain individuals at very high risk, doctors may occasionally recommend specific medications like low-dose aspirin, but this is highly personalised. Focus on healthy daily habits and regular routine screenings, which are your best defence.