Strengthening Argument About Green Tea and Cholesterol

In a recent study, researchers found that individuals who regularly consume green tea have lower levels of cholesterol compared to those who do not. The study concluded that drinking green tea helps reduce cholesterol levels. However, some nutritionists argue that the study does not sufficiently consider other potential factors, such as diet and exercise habits, that could contribute to cholesterol levels.

To strengthen the conclusion that drinking green tea is effective in reducing cholesterol levels, which of the following pieces of information would be most helpful?