The cup landed on my desk with the soft thunk of ice and tapioca pearls settling at the bottom. My patient that morning, a composite drawn from many similar consultations, was a software analyst in her early thirties here for a routine screening, and she slid it across with a grin. "Doc, I saw the news. Tea is good for the heart and the brain now, right? So this," she tapped the brown sugar bubble tea, "is basically medicine." She was half joking. But only half. She drinks one most days, sometimes two, and a headline had just handed her permission.
She had seen real coverage. In June this year, a review in the journal Beverage Plant Research made the rounds of the health press, and the summary line was hard to resist: tea may help protect against heart disease, diabetes, certain cancers, cognitive decline and age-related muscle loss (1). All true to the evidence, broadly. But the same review carried a second half that almost none of the headlines mentioned, and it is the half that matters most in Singapore, where the tea most of us actually drink is sweet, milky, and increasingly served with pearls.
So here is the question worth answering honestly, because it decides whether that cup is helping or quietly working against her: when the science says "tea is good for you", does it mean the tea in her hand? And if you want the longevity benefit the headlines promised, what do you actually have to do? Let me walk through what the evidence shows.
What the Headline Got Right
Start with the good news, because it is real. Tea, brewed from the leaves of Camellia sinensis, is rich in polyphenols, particularly a family of catechins, of which the most studied is EGCG in green tea. These compounds are antioxidant and anti-inflammatory in the laboratory, and the population data line up with the mechanism more often than not. The 2025 review pulled together cohort and experimental studies showing that regular tea drinking is associated with lower blood pressure, better cholesterol profiles, improved control of blood sugar, and a lower risk of death from all causes and from cardiovascular disease in particular (1). This is not a fringe finding. A 2024 meta-analysis by Kim and Je that pooled 38 cohorts and nearly two million people found the heaviest tea drinkers had roughly a 10 per cent lower risk of dying from any cause, and about a 14 per cent lower risk of cardiovascular death, than the lightest, though, as ever with this kind of data, the studies can show a link but not prove tea was the cause (8).
The single strongest piece of evidence here is not from a small lab study but from half a million people. Maki Inoue-Choi and colleagues at the US National Cancer Institute followed nearly 500,000 adults in the UK Biobank for a median of around eleven years, and published the results in the Annals of Internal Medicine in 2022 (2). People who drank two or more cups of tea a day had a 9 to 13 per cent lower risk of dying during the study than non-tea drinkers, with the clearest signal for deaths from heart disease and stroke. Strikingly, the association held whether people drank their tea with milk or sugar, whatever temperature they preferred, and regardless of genetic variants that change how fast they clear caffeine.
Two honest caveats before anyone frames that on the wall. This was black tea, the British staple, not bubble tea. And it is an observational study, which means it can show a link but cannot prove the tea itself did the work. The researchers said so plainly, and the lead author's own comment was that people should not start drinking tea on the strength of it. The fair read is that tea fits comfortably inside a healthy pattern of living, not that it is a drug you can prescribe.
The Singapore Study Most People Have Never Heard Of
The brain part of the headline has a local anchor, and it is a good one. Researchers at the National University of Singapore, led by Feng Lei and Ng Tze Pin, ran the Singapore Longitudinal Ageing Study, following 957 community-living older Chinese Singaporeans who were cognitively intact at the start (3). They recorded tea habits between 2003 and 2005, then tracked who developed a neurocognitive disorder over the next several years.
Regular tea drinkers had a markedly lower risk. The reduction held for both green tea and black or oolong tea, and the effect was strongest in those who drank tea consistently over time rather than starting and stopping. The numbers are eye-catching, but they come with the usual honesty: only 72 people developed a disorder, the study is observational, and tea drinkers in that generation may simply have led calmer, more socially connected, more routine-driven lives that protect the brain on their own. It is a reason to feel good about a daily pot of Chinese tea. It is not a reason to believe a cup undoes a decade of poor sleep and no exercise.
Now the Catch the Headlines Buried
Here is where the same review turns its hand against the modern cup. The benefits in the data come from tea, the brewed leaf, and largely from tea drunk without much added to it. The moment you move to bottled iced teas and, above all, bubble tea, you add sugar, sometimes a great deal of it, along with sweeteners and other additives, and the review is explicit that this can reduce or cancel out the good (1). Tea is the part that helps. Sugar is the part that, in the quantities Singapore serves it, does the opposite.
The arithmetic is sobering. A widely cited analysis by Mount Alvernia Hospital here in Singapore found that a brown sugar pearl milk tea, the photogenic one with the syrup streaking down the cup, can carry around 18 and a half teaspoons of sugar. A 500ml serving works out to roughly 92 grams of sugar, about three times what is in a regular can of Coke (4). Even a plain bubble milk tea with pearls runs around 8 teaspoons in a 500ml cup and about 11 in the larger 700ml size (4). For comparison, the World Health Organization recommends keeping free sugars under 10 per cent of daily energy, around 12 teaspoons for an average adult, and ideally under half that for additional benefit. A single brown sugar boba can blow past a whole day's ceiling in one sitting.
The Singapore authorities clearly think this is a problem worth acting on. Since 30 December 2023, the Health Promotion Board's Nutri-Grade scheme has applied to freshly prepared drinks, bubble tea included, so that cups graded C or D for sugar and saturated fat must show the grade, and pearls, jellies and other toppings now carry their own sugar declaration (5). That label exists precisely because freshly prepared sugary drinks became one of the largest and fastest-growing sources of sugar in the Singaporean diet. The drink with the tea leaf in its name had quietly become a dessert.
And Yes, Teh Tarik Counts Too
It would be easy to read this as a young person's bubble tea problem, but the kopitiam version is the same story in older clothes. A standard teh, and especially a teh tarik pulled to that lovely froth, is tea brewed strong then sweetened with sugar and condensed or evaporated milk. The tea underneath is genuinely fine. It is the two or three teaspoons of sugar and the sweetened condensed milk that turn a healthful drink into one more sugar load across a day that already has several.
The good news is that the Singapore coffee shop gave us the solution before the science asked for it. The ordering lingo is a built-in dial for sugar. Ask for your teh "siu dai" and you get less sweetened milk. Ask for it "kosong" or "O kosong" and you get it without sugar at all, closer to the brewed tea the studies actually reward. None of this means giving up the ritual. It means ordering the version that keeps the part with the evidence behind it and drops the part the evidence warns about. Same pull, same froth, far less sugar.
The Iron Catch Worth Knowing
One genuine downside of tea has nothing to do with sugar. The same polyphenols that do the good work also bind to non-haem iron, the form of iron found in plant foods, and block a chunk of its absorption when tea is drunk with a meal. This is old, solid science: a classic 1975 study in the journal Gut showed tea taken with food could cut iron absorption substantially, and later work has confirmed that strong tea alongside an iron-rich meal can reduce uptake by more than half (6, 7).
For most people with healthy iron stores this is a non-issue. But it matters for a specific group: those who are already low on iron or prone to it, including women with heavy periods, pregnant women, frequent blood donors, and people eating mostly plant-based diets who rely on non-haem iron in the first place. If that is you, the fix is not to give up tea but to put a gap between it and your iron. Drinking tea an hour or two away from your main meals, rather than with them, sharply reduces the interference (7). And if you have been told you are anaemic or are taking an iron supplement, the timing of your tea is worth raising with your own doctor or pharmacist, because it can genuinely affect how well the treatment works.
A Quick Word on Caffeine
Tea is not caffeine-free, and the dose adds up across a day of teh and the occasional kopi. For most adults this is harmless and even part of the alertness people enjoy. But if you are pregnant, current guidance is to keep total caffeine to a modest daily limit, and tea counts towards it alongside coffee and cola. If you are prone to anxiety, palpitations, reflux or broken sleep, a strong cup late in the day can be the quiet culprit. As with most things, the dose and the timing matter more than the yes-or-no.
The Honest Read
Tea, the brewed leaf, has earned its reputation. The signal across large cohorts is that regular, lightly adorned tea drinking sits inside a longer, healthier life, with the strongest evidence for the heart and reasonable, locally grounded evidence for the ageing brain (1, 2, 3). That is worth enjoying without overthinking it. What has not earned the reputation is the sweet, milky, pearl-laden version that dominates the Singapore cup. The tea in a brown sugar bubble tea is doing a little good while the sugar around it does a lot more harm, and no amount of catechin rescues 18 teaspoons of sugar (1, 4).
The useful move is not to treat tea as medicine, because it is not, and the people who study it are the first to say so. It is to enjoy tea closer to the form the evidence actually rewards: brewed, and either unsweetened or only lightly so. Kosong is not deprivation. It is simply ordering the cup the research was talking about.
And the foundations still sit underneath all of it. No tea, green or black or oolong, outranks not smoking, sleeping enough, moving your body, keeping your weight and blood pressure in a healthy range, and eating mostly real food. Tea is a pleasant, plausibly helpful layer on top of those. It was never going to be the thing that carries them.
What My Patient Went Home With
I did not tell her to give up bubble tea, because that advice never survives contact with real life and she would simply have stopped listening. We counted instead. One brown sugar boba most days was adding, on its own, more sugar than her entire recommended daily allowance, on top of everything else she ate. So we made it a treat rather than a habit: the full pearl version once a week if she fancied it, and on the other days, either a brewed tea she actually likes without the syrup, or her kopitiam order switched to siu dai. She also mentioned she had been feeling tired, and given she is vegetarian, I suggested we check her iron at this screening and, separately, that she stop washing her lunch down with strong tea. Small changes, none of them about willpower, all of them about keeping the part with the evidence and trimming the part without it.
She picked up the cup, looked at it differently, and said, "So it's not medicine." Not quite, I told her. The tea inside it almost is. It is everything we pour on top that turns it back into dessert.
If you are weighing up your own tea habit, especially if you are pregnant, have anaemia or iron deficiency, are managing diabetes or blood sugar, or take any medication that interacts with caffeine, talk it through with your own doctor, who knows your history and your numbers and can tell you what fits you specifically rather than what suits a headline.