给出一篇英文论文，输出其中出现最多的三个词汇。
英文论文：The effect of caffeine on human health has long been a subject of debate. While some studies suggest that moderate consumption of caffeine can have various benefits, other studies have warned about the adverse effects of caffeine addiction, such as anxiety and insomnia. The debate over caffeine consumption continues to this day, with no clear consensus on its benefits or harms.
caffeine, consumption, studies