The Claim: Along with reducing heart disease, dementia and cancer risk, green tea also speeds up metabolism.

Metabolism Effect: Results are mixed; some studies suggest a slight increase in metabolism, while others suggest no change in calories burned but an increase in fat tissue breakdown. While caffeine may play a small role, researchers cite catechin compounds in green tea for any metabolic improvements.

Our Verdict: Sipping green tea likely isn't going to be a "magic bullet" for weight loss, but it may help you burn a few more calories. And, even if it doesn't, you're still saving calories by swapping it for a soda and possibly reducing risk for other conditions.

*Speculated but not proven

Photo: Elena Kovyrzina/Getty

Thousands of years old and one of the most frequently consumed beverages worldwide, tea has been touted as a healthful elixir due to its concentrated amounts of antioxidants. From reducing heart disease and cancer risk to promoting weight loss and blood sugar control, tea is recognized for much more than its ability to soothe, refresh, and restore. Though this poses the question -- are all teas created equal? Is green tea superior? What about matcha? Here, we give you the low-down on why we have the hots for tea.

Jamie Vespa, MS, RD
January 19, 2017

Origin of Green Tea

Tea is brewed from the dried leaves of the Camellia sinensis bush and can be categorized into four types, depending on the level of oxidation: white (unoxidized buds), green (unoxidized leaves), oolong (partially oxidized leaves), and black (oxidized leaves). The health benefits of tea stem from the antioxidants it contains, primarily flavonoids, also known as catechins. All teas contain antioxidants, though green and black teas contain the highest amounts of flavonoids.[1] Other factors that determine the antioxidant levels of tea include tea quality, origin of growth, brewing method, and brewing time. The antioxidant levels in dry tea leaves are much higher than those in brewed tea because the tea leaves are discarded after the brewing process.

Health Benefits of Green Tea

Tea has shown promising benefits in association to heart health. Flavonoids in green tea can help prevent oxidation of LDL (bad) cholesterol and reduce blood clotting. Studies show green tea can also help lower blood pressure, triglycerides, and total and LDL cholesterol.[2] In addition to cardiovascular health, tea extracts and polyphenols have also shown promising effects in cancer research. Tea and tea components have been shown to inhibit carcinogen-induced DNA damage in a number of cell studies, as well as inhibit tumor development at different organ sites.[3]
As far as diabetes and the relationship between tea consumption and blood sugar control, findings have been inconsistent. Evidence supporting tea as a weight-loss aid is based mainly on studies testing the effects of teas extracts, such as catechins and caffeine, so results may not be directly applicable to brewed tea. However, research suggests green tea catechins and caffeine may stimulate thermogenesis, leading to a potential increase in energy expenditure.

What About Matcha?

Matcha is a very fine, high-quality green tea powder made from the leaves of tea bushes grown in the shade. It is the only form of tea in which the leaves are ingested, making it a more potent source of antioxidants than steeped green tea. Matcha is a particularly rich source of L-theanine, an amino acid unique to tea known to mitigate the negative effects of caffeine. Try a hit of matcha in a Coconut Latte, a yogurt parfait, or in a chocolate-dipped shortbread cookie.

Bottom Line: As part of a nutrient-rich diet, tea does have potential to enhance health and mitigate disease risk. Tea is an excellent calorie-free alternative to sugary beverages that also provides health-promoting phytochemicals. Try a fresh batch of home-brewed Lemon Green Tea to reap the many benefits of this medicinal elixir.

Article Resources
[1] Peterson J, Dwyer J, Bhagwat S, et al. Major flavonoids in dry tea. J Food Comp Anal. 2005;18(6):487-501.
[2] Khalesi S, Sun J, Buys N, Jamshidi A, Nikbakht-Nasrabadi E, Khosravi-Boroujeni H. Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. Eur J Nutr. 2014;53(6):1299-1311.
[3] Yang CS, Lambert JD, Sang S. Antioxidative and anti-carcinogenic activities of tea polyphenols. Arch Toxicol. 2009;83(1):11-21.