Unanticipated Advantages Of Drinking Green Tea

One advantage attached to green tea is weight loss. A Cochrane review opens by noting that “preparations of green tea are used as aids in weight loss and weight maintenance”, and its authors concluded that the weight loss was small and “not likely to be clinically important”. The advantages that do hold up are plainer, and they come from what is actually in the cup.

It counts as part of your fluids

The NHS page on water and drinks says the UK government recommends that people “aim to drink 6 to 8 cups or glasses of fluid a day”. It then says that “water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count as part of your daily intake.”

The condition in that sentence matters. Tea counts as a lower-sugar drink when it stays low in sugar. A cup with three spoons of sugar is a different drink. For people who take sugar in hot drinks, the NHS sugar page suggests they “gradually reduce the amount until you can cut it out altogether.”

Less caffeine than a cup of coffee

USDA FoodData Central (SR Legacy) lists brewed green tea at 12 mg of caffeine per 100 g, and gives a cup as 245 g. That works out to about 29 mg a cup. The same database lists brewed black tea at 20 mg per 100 g, about 47 mg in a 237 g cup, and brewed coffee at 40 mg per 100 g, about 95 mg in a 237 g cup.

The European Food Safety Authority (EFSA) gives similar figures for black tea and coffee. Its caffeine page puts a 220 ml cup of black tea at 50 mg and a 200 ml cup of filter coffee at 90 mg, and notes that “all figures are approximate”.

So a cup of green tea carries roughly a third of the caffeine of a cup of brewed coffee. EFSA says intakes “up to 400mg per day” spread through the day “do not raise safety concerns for healthy adults in the general population”, with an exception for pregnant women. On the FDC figure, that limit is more than 13 cups of brewed green tea. EFSA also says single doses of 100 mg “may affect sleep duration and patterns in some adults, particularly when consumed close to bedtime.” One cup sits well below that. Three cups in a row would come to about 88 mg.

Almost nothing on the calorie side

FDC lists brewed green tea at 99.9 g of water and 1 kcal per 100 g, so a 245 g cup comes to about 2 kcal. Anything stirred in adds to that figure, so the near-zero number only belongs to an unsweetened cup.

Where a date fits next to the cup

The NHS 5 A Day page says “a 30g portion of dried fruit, such as currants, dates, sultanas and figs, counts as 1 of your 5 A Day, but should be eaten at mealtimes, not as a snack between meals, to reduce the impact on teeth”. So the date belongs with a meal and the cup, not on its own in the middle of the afternoon.

FDC gives one pitted Deglet Noor date as 7.1 g, at 282 kcal per 100 g. Four of them weigh 28.4 g, close to the NHS portion, and add about 80 kcal. FDC lists their caffeine as 0 mg, so the date adds sweetness to the table without adding to the caffeine count. A Medjool date is larger: FDC gives one as 24 g, at 277 kcal per 100 g, or about 66 kcal each. If you want something sweet with the cup, a date at a meal is one option, and it keeps the sugar out of the tea itself.

The advantage that did not hold up

A 2012 Cochrane review (Jurgens and colleagues, PubMed 23235664) looked at randomised trials of at least 12 weeks that compared green tea preparations with a control in overweight or obese adults. Six studies done outside Japan, with 532 participants, could be pooled. The average difference in weight loss was 0.04 kg, and it was not statistically significant. Eight studies from Japan were too different to pool; their results ranged from 0.2 kg to 3.5 kg in favour of green tea. The authors concluded that the weight loss was small and “not likely to be clinically important”.

That is a useful finding in its own way. A cup of tea does not need to melt weight to be worth drinking. Its real advantages are the ones above. It counts towards your daily fluids, and next to brewed coffee it carries far less caffeine.

For more on how food trials measure eating habits, see what chewing trials found about how much people eat. Background on Rotab Mazafati Bam is on the About page, and the Contact page lists its WhatsApp number.