Betel leaf (piper betle) has been used for centuries as a treatment of a range of ailments. However, the properties of betel leaf or betel pepper as a cure-all for many ailments has likely been overstated.

What we do know is that studies on rats to understand Alzheimer's disease, hydroxychavicol, which is a major part of the betel leaf (piper betle), was shown to improve cognitive impairment. 

The compound has been thought to have potential protection against chronic diseases like cardiovascular disease and arthritis.

However, more research – especially larger scale studies on humans – is needed to more fully understand the potential benefits of piper betel in humans.

In addition, betel leaves should not be confused with betel nuts, also known as the areca nut which is also chewed as a stimulant in many parts of the world. It can cause effects similar to tobacco and alcohol. But where it’s different from betel leaf is that many studies have shown a strong link between betel nut chewing and cancer of the mouth and esophagus.

Betel leaf has been used as a medicinal herb since 400 B.C. It has also had other uses, such as to help digest meals by chewing on the leaves which was common between 75 and 300 A.D. In fact, Marco Polo recorded betel chewing among upper classes in India. However, these uses of betel were before any studies had been done on the plant.

We now know that betel leaf's hydroxychavicol has many potential health benefits. That being said, more studies - including clinical trials specific to unique diseases - are still needed. Most research with health benefits involves testing in rat or mice models, which does not translate directly to human benefit.

Though human studies are greatly needed, betel leaf may have anti-inflammatory benefits in the field of depression and rheumatoid arthritis; benefits in diabetes, cancer, and cough; and offer some oral health support.