If you have cancer, your body's normal cells change and start acting differently. The changing cells cause tumours to grow.
But scientists have discovered caffeine and theophylline can block the chemical signals that tell cells to change.
If they can make a medicine out the chemicals, it could help fight illnesses like heart disease too.
Don't over-do it!
But it takes a scientist to make the medicine.
They say we should not try and drink loads of coffee and binge on chocolate thinking it's good for us.
It would be unhealthy and dangerous because of the amount of caffeine needed to treat diseases. So leave it to the experts!