Health Benefits of Tea: Is Tea Good for You? What Research Has and Has Not Shown About Green, Black, White and Oolong Tea

A remedy long before it was a drink

Tea has carried a reputation as a remedy for a very long time. In ancient China, people added herbs, and even onions, to tea to strengthen what they saw as its healthful properties.

When tea first reached the West, buyers went to an apothecary, not a tea shop, because it was sold as an herbal tonic for the skin, the stomach, sleepiness and memory. Our blog has traced the same thread through Japanese practice and the Ayurveda tradition of India, and noted that the very first recorded advertisement for tea in England highlighted that apothecaries recommended it.

What modern research says

Modern research tells a more modest story. When Peter Keen took the question on for our blog in 2016, his answer to “does tea prevent and cure illness?” was “Yes, No, Maybe and Possibly,” and he added a warning we still repeat: when an ad says a health link is “proven,” “it isn’t at all.”

He summed up the record in a line we still stand by: it is “mildly suggestive but not supportive of claims of specific benefits,” and study conclusions are “invariably littered with ‘may,’ ‘suggests,’ ‘potentially.’” His verdict on whether tea adds to well-being was “somewhere between ‘doubtful’ and ‘could well be,’” and “in no way is it a ‘Yes.’”

Our own older Tea 101 articles on green, black, white and oolong tea went much further than that, with lists of diseases tea was said to prevent. We have rewritten them as this guide, because those claims went beyond the evidence.

What tea reliably offers

What tea reliably offers is simpler: flavor, warmth, a little caffeine and a pause in the day. Aravinda Anantharaman, then our senior editor, put the house view plainly in 2016: drink tea or coffee “for pleasure,” because neither is “an antidote for ailments.”

In a martial arts school in Japan, students broke off from two hours of sword and knife training to sit on the dojo floor with a cup of green tea; one of them described it as “a time of quiet contemplation, reflection, and rest.” A Teabox writer once put it more bluntly: the health hype “overshadows the one actual reason why you should drink it,” which is how a good cup makes you feel at the end of a long day.

Our training deck puts a brewed cup at “on average 98% water and 2% compounds from within the tea leaves.” Green, black, white and oolong tea all come from the same plant, Camellia sinensis; how the leaf is processed changes which compounds end up in that 2%. See Types of tea for how each is made.

The range of questions is wide. Keen listed studies on tea and cold cures, cancer prevention, blood pressure, diabetes, depression, weight reduction, ulcers, rheumatism and liver function, and found that none had yet produced a claim that “passes basic tests of statistical reliability, replication, predictive validity, or generalizable results.” A small study of green tea drinkers over a few months, he wrote, is “suggestive or promising” at most.

Our 2014 blog made the animal point memorably: tea has shown effects against cancer in mice, “but there are no conclusive results to prove the same works on human beings.” Our 2016 blog was harder still on marketing, calling the industry’s health copy “an area of massive misinformation: ignore it all,” with examples such as a pu-erh “renowned for lowering cholesterol” and an oolong said to be “naturally melting away belly fat.”

A useful rule: words such as “may,” “is linked to” and “studies suggest” are honest; words such as “proven,” “cures,” “detox,” “boosts immunity” and “burns fat” go beyond what the evidence on tea supports. For the most common claims and what lies behind them, see Tea and health myths.

Each type has its own reputation: green for catechins, black for heart studies, white for “more antioxidants” and oolong for weight. On a separate page we take each in turn, say what has been studied, and say plainly which of our own old claims we have withdrawn.

Caffeine varies with the leaf, how much you use, water temperature and steeping time. Figures are Tea 101’s approximate ones. Polyphenol and catechin percentages are from our staff training deck, which does not name its source; they describe the dry leaf, not a cup, and say nothing about health. Ratings are the High, Medium, Low and Caffeine free labels on our product pages, October 2026.

The deck’s figures show why processing, not virtue, separates the teas. White and green tea keep most of the leaf’s catechins, while in black tea oxidation has turned most of them into theaflavins and thearubigins, so its catechin figure drops to about a third of green’s. The total polyphenols differ far less, from 16.5% to 21.5%.

Whichever you choose, the things that change a cup most are the ones you add: sugar, milk and cream. If you would like less caffeine, green tea (about 20 to 45 mg a cup by Tea 101’s figure) or a caffeine-free herbal infusion are the lower-caffeine options.

Ayurveda, from ayur (life) and veda (knowledge), describes the body in terms of three energies, or doshas: Vata (air and space), Pitta (fire and water) and Kapha (earth and water), and frames food, season and daily routine around keeping them in balance.

Much of this wisdom was handed down at home rather than in books: a grandmother’s spiced milk for a winter cold is part of growing up in many Indian families. Our own herbal blends have drawn on Ayurvedic ingredients such as haritaki, one of the three dried fruits that make up the traditional Ayurvedic formula Triphala. Other traditions have their herbal cups too. The ancient Egyptians, as we wrote on World Sleep Day in 2024, believed chamomile flowers helped them sleep peacefully.

Our Ayurvedic chais, by ingredient

Our Ayurvedic chais carry these traditions into the cup. We make them to be enjoyed for their flavor and their place in Indian life, and we describe them here only by what goes into them.

• Rajasik: Rajasik Ayurvedic Chai, a morning chai, blends tea with ginger, black pepper, tulsi and green cardamom.
• Ojas Ras: Assam CTC black tea with spearmint, lemongrass, nutmeg and ginger.
• Ashoka Ras: black tea with rose, licorice, ginger, cardamom and cinnamon.
• Abhay Ras: hibiscus, amla, tulsi and bay leaf, with no tea leaf, so it is caffeine free.

The ones made with tea leaf carry a High caffeine rating on our product pages, like any strong chai. For single herbs, see Tulsi (holy basil) tea and Herbal tea (tisanes).

One caution that is about plants, not promises: herbs are active ingredients in their own right, and some people are advised to avoid particular ones. Our 2016 blog warned that herbal products carry risks of interactions between herbs, allergic reactions and uneven quality control. If you have a health condition, are pregnant or take medication, check with your doctor before making an herbal drink a daily habit.

• Caffeine. Using Tea 101’s rough figures, a cup of black tea has about 50 mg and green tea about 20 to 45 mg, roughly half or less of a cup of coffee. If tea leaves you jittery or keeps you awake, drink less of it, brew it lighter, have it earlier in the day, or switch some cups to a caffeine-free herbal infusion. Coffee drinkers can compare the two in Caffeine in tea.
• Read the rating. Every Teabox tea carries a High, Medium, Low or Caffeine free label. Blends named for the evening or for calm can still contain tea leaf: our Chamomile Green blends chamomile with green tea, so unlike Pure Chamomile it does contain caffeine.
• Iron. Our 2015 blog noted that the tannins in tea can block the absorption of iron, “something to note if you’re anemic or your hemoglobin levels are low.” If that applies to you, ask your doctor whether the timing of your tea matters.
• Pregnancy. Caffeine and some herbs are a particular question in pregnancy. Our guide to Tea during pregnancy explains what to ask your doctor or midwife.
• What you add. Several sweet, milky cups a day add up in sugar and calories in a way plain tea does not.

When customers write to us with questions about pregnancy or a medical condition, we answer as tea makers, not doctors: we point them to their own healthcare provider, and we are happy to share the full ingredient list of any blend to help that conversation.

Our 2014 blog had a word for people who drink ten cups of green tea a day “because they’re really into fitness”: tea is not a “magical elixir,” and if it were, “we folks at Teabox have chugged enough to become superhumans.”