The health benefits of tea have been the subject of much research; in addition to its possibilities for preventing and inhibiting some forms of cancer, the brewed leaves of camellia sinensis may also play a role in reducing the risk of heart disease and stroke.

The sentence ' The health benefits of tea have been the subject of much research; in addition to its possibilities for preventing and inhibiting some forms of cancer, the brewed leaves of Camellia sinensis may also play a role in reducing the risk of heart disease and stroke' can be properly written in the following format.

The health benefits of tea have been the subject of much research; besides possibly preventing or inhibiting some forms of cancer, the brewed leaves of Camellia sinensis may also play a role in reducing the risk of heart disease and stroke.

This is because with a plural subject, a singular pronoun cannot be used. Hence, it or it's cannot be used.

the gravitational force on an object increase as the mass of an object also, im not going to report you, but this question should be under the science category, not health