Green tea contains a variety of enzymes, amino acids, carbohydrates, lipids, sterols, related compounds, phytochemicals, and dietary minerals. Numerous claims have been made for the health benefits of green tea based on chemical composition, in vitro and animal studies, and while preliminary research on many of these claims is promising, many also require further study to evaluate.[17] There is also evidence suggesting consuming large volumes of green tea, and in particularly green tea extracts, may cause oxidative stress and liver toxicity.