Nutritional breakdown of green tea
Unsweetened brewed green tea is a zero calorie beverage. The caffeine contained in a cup of tea can vary according to length of infusing time and the amount of tea infused.
In general, green tea contains a relatively small amount of caffeine (approximately 20-45 milligrams per 8 oz cup), compared with black tea which contains about 50 milligrams and coffee with 95 milligrams per cup.2
Green tea is considered one of the world’s healthiest drinks and contains one of the highest amount of antioxidants of any tea. Researchers commonly speak highly of green tea – Christopher Ochner, PhD, a research scientist in nutrition at the Icahn School of Medicine at Mount Sinai Hospital, is quoted by health website WebMD as saying, “it’s the healthiest thing I can think of to drink.”
The natural chemicals called polyphenols in tea are what are thought to provide its anti-inflammatory and anti-carcinogenic effects.
Epigallocatechin-3-gallate (EGCG) is the most studied and bioactive polyphenol in tea and has been shown to be the most effective at eliminating free radicals.1, 4
Green tea is approximately 20% to 45% polyphenols by weight, of which 60% to 80% are catechins such as EGCG.1 These catechins are antioxidants that are said to possibly help with fighting and preventing cell damage.
Forms of green tea
Green tea is available bottled and sweetened with sugar or an artificial sweetener, in single tea bags, loose-leaf, and in instant-powder.
Green tea is available bottled and sweetened with sugar or an artificial sweetener, in single tea bags, loose-leaf, and in instant-powder. Green tea supplements are sold in capsule form or liquid extracts.
According to 2010 research presented at the American Chemical Society, bottled teas are not equivalent to brewed teas as some 16-oz bottled teas can contain fewer polyphenols than one cup of brewed tea.1
Green tea extract ointments have been approved by the FDA to topically treat genital warts.
Precautions and risks associated with green tea
There are little to no known side effects or contraindications to drinking green tea for adults. Those with severe caffeine sensitivities could experience insomnia, anxiety, irritability, nausea or upset stomach.3
Those taking anticoagulant drugs such as Coumadin/warfarin should drink green tea with caution due to its vitamin K content.3
If taken with stimulant drugs, green tea could possibly increase blood pressure and heart rate.3
Green tea supplements however, contain high levels of active substances that can trigger side effects and interact with other herbs, supplements, or medications.4 Green tea supplements are unregulated by the FDA and may also contain other substances unsafe for health or with unproven health benefits. Always check with a physician before starting any herb or supplement regimen.
In particular, pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should not take green tea supplements or extracts.4
Recent developments on risks associated with green tea from MNT news
Could too much green tea be harmful to health?
For centuries, green tea has been hailed for its numerous health benefits. But according to a new study, the beverage could do more harm than good if consumed in large amounts.
Have you enjoyed reading about the potential health benefits of green tea? Take a look at our collection of articles about other fruits and vegetables.