It seems that every day a new study shows coffee has protective effects of some sort. In recent studies coffee has been found to reduce the risk of developing breast, liver, endometrial, prostate, oral, skin and other cancers. Coffee may also be beneficial in protecting against diabetes and, contrary to what we've been told about coffee and heart health, coffee may reduce the risk of stroke.
Most of this research has not shown causality - or a direct relationship of drinking coffee and preventing cancer or other health problems. The type and amount of coffee required to reduce cancer risks has yet to be determined. Is there a safe amount of coffee consumption? That is yet to be determined. Are some people at a higher risk of the bad side effects of coffee? Probably. Does the caffeine in other products have the same effect? Unknown.
As the saying goes, moderation is key. Drinking coffee in moderation is likely safe for most people, and may actually reduce the risk of developing certain cancers, diabetes, and stroke. But, more research is necessary to make this claim. At this time, healthcare providers are not ready to "prescribe" coffee consumption to prevent disease.