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STRUCTURED COMPARISON
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Choose two categories from the same family. The same properties, equal visual weight, sources next to the claims they support.
STRUCTURED COMPARISON
Choose two categories from the same family. The same properties, equal visual weight, sources next to the claims they support.
Beverages
Coffee is a brewed beverage made from roasted, ground seeds of the Coffea plant, consumed worldwide in forms ranging from espresso to filter and instant. A typical cup contributes water, caffeine, and hundreds of plant compounds, with negligible calories when unsweetened. Composition varies with species (arabica, robusta), roast level, grind, and brewing method. Harvard's Nutrition Source describes coffee as compatible with a healthy diet for most adults in moderate amounts. Effects and content differ by preparation and individual tolerance, so single figures are averages rather than fixed values. Additives such as sugar, cream, and syrups can substantially change its nutritional profile.
Tea is an infusion prepared from leaves of Camellia sinensis, producing green, black, oolong, and white types that differ mainly by oxidation. Herbal 'teas' such as chamomile or rooibos come from other plants and have different profiles. A plain cup supplies water, caffeine, and characteristic polyphenols, with essentially no calories unsweetened. Content varies with cultivar, processing, leaf quantity, water temperature, and steeping time. Harvard's Nutrition Source lists tea among beverages compatible with a healthy dietary pattern. Reported values are averages, since brewing choices and additions like milk, sugar, or honey meaningfully alter what ends up in the cup.
Coffee is produced by roasting green beans: it is roasting that turns the raw material into something to brew. Commercial roast levels — light, medium and dark — differ measurably in phenolic content and in the set of volatile compounds responsible for aroma. In measurement, light roasting retains more phenolics than darker roasting.
Caffeine in coffee varies widely, but an 8-ounce (240 ml) brewed cup commonly provides roughly 80-100 mg, with espresso shots concentrated into smaller volumes. Robusta beans typically contain more caffeine than arabica, and drip method, dose, and grind all shift the total. EFSA considers single doses up to about 200 mg and habitual intakes up to 400 mg per day unlikely to raise safety concerns for healthy adults, with lower limits during pregnancy. Because cup sizes and strengths differ, published averages should be read as ranges. Individual sensitivity, medications, and tolerance also influence how a given amount is experienced.
The profile of the drink is set not by the raw material alone but by roasting: the commercial levels — light, medium, dark — differ measurably in phenolic content and in the set of volatile compounds responsible for aroma. In measurement, light roasting retains more phenolics than darker roasting. So 'the taste of coffee' is a property of a particular lot and its processing, not of the category.
Because coffee is mostly water, moderate consumption contributes to daily fluid intake rather than causing net dehydration, contrary to a common belief. Caffeine has a mild diuretic effect at higher doses, but studies in habitual drinkers show little meaningful fluid loss at typical intakes, and tolerance reduces the effect further. Harvard's Nutrition Source and beverage guidance generally count moderate coffee toward hydration. Very high caffeine doses, or coffee drinks loaded with sugar and cream, complicate the picture and shift attention to other health considerations. For most healthy adults, unsweetened coffee in moderation is compatible with adequate hydration.
Coffee preparation spans espresso, drip or filter, French press, moka pot, cold brew, and instant, each altering strength, extraction, and which compounds reach the cup. Water temperature, grind size, coffee-to-water ratio, and contact time drive extraction; paper filters notably trap cholesterol-raising diterpenes that metal or no filter allow through. Cold brew uses long steeping at low temperature, often yielding a smoother, less acidic profile. These choices change caffeine, polyphenol, and diterpene content substantially, which is why nutrient figures are method-dependent. Common additions of milk, sugar, cream, or flavored syrups can add significant calories and reshape the drink's overall profile.
The body whose opinions regulators rely on states the figures plainly: a single caffeine dose up to 200 mg (about 3 mg per kilogram of body weight for a 70-kg adult) does not give rise to safety concerns; habitual consumption up to 400 mg a day does not give rise to concerns for non-pregnant adults, while for pregnant women the stated figure is 200 mg a day. The figures apply to caffeine from ALL dietary sources, not to one drink, so a cup of coffee spends part of the shared daily allowance. Authorities differ on the figure for pregnancy: the body cited here states 200 mg a day, while a 2017 systematic review tested the evidence against Health Canada's figure of 300 mg a day. The difference is between authorities, not an error in this row.
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Both drinks are water extracts of plant material containing caffeine and polyphenols. The differences run along the amount of caffeine, the set of bioactive compounds and the method of preparation. The contribution to fluid balance is assessed differently, although both drinks count towards it. Health evidence on both sides is largely observational: association does not establish causation, and studies of extracts do not carry over to the brewed drink.
FREQUENTLY EXPLORED
Fresh Camellia sinensis leaves are processed by different techniques, and it is the processing method that underlies the accepted division into white, green, oolong, black and pu-erh. Differences in the degree and nature of fermentation lead to different chemical changes, and the aroma compounds form during the manufacturing process itself. At the same time the chemical parameters for tea types are still not established, and the effect of processing on the phytochemical profile remains unclear in the literature.
Tea generally contains less caffeine per cup than brewed coffee, though it is far from caffeine-free. An 8-ounce cup of black tea often provides roughly 30-50 mg, green tea somewhat less, while decaffeinated and most herbal infusions contain little or none. Amounts depend on tea type, leaf quantity, water temperature, and steeping time, so longer, hotter brews extract more. EFSA's caffeine advice applies across all sources combined, so tea counts toward the same daily totals as coffee and cola. As with coffee, listed figures are averages, and individual sensitivity and habitual intake shape the practical effect.
Beyond caffeine, coffee is a major dietary source of chlorogenic acids and other polyphenols, along with diterpenes such as cafestol and kahweol. Unfiltered coffee (French press, boiled, some espresso) retains more diterpenes, which have been linked in studies to modest increases in blood cholesterol, whereas paper filtering removes much of them. Antioxidant and other compound levels vary with bean, roast, and brew. Harvard's Nutrition Source notes coffee contributes meaningfully to polyphenol intake in many diets. The biological importance of individual compounds remains an active research area rather than settled fact, and laboratory measures do not translate directly into human outcomes.
Tea's characteristic compounds are polyphenols known as catechins, notably EGCG in green tea, along with theaflavins and thearubigins formed when black tea is oxidised. It also supplies the amino acid L-theanine, studied for possible effects on relaxation and attention, and flavonoids that contribute to antioxidant capacity in the diet. Concentrations depend heavily on type and brewing, with green tea generally richer in catechins and black tea in oxidised polyphenols. Harvard's Nutrition Source highlights tea as a flavonoid source within healthy patterns. As with coffee, laboratory antioxidant measures do not translate directly into proven health outcomes in people.
The flavour of tea divides in two: taste comes from non-volatile compounds, aroma from volatile ones. The aroma molecules form during the manufacturing process itself, from carotenoids, lipids, glycosides and by the Maillard reaction, and their set differs between green, black and oolong tea. The profile is therefore set by how the leaf is processed, not by the plant variety alone.
Tea, being largely water with lower caffeine than coffee, likewise counts toward daily fluid intake for most people, and the older idea that caffeinated drinks are dehydrating is not well supported at ordinary intakes. Herbal and decaffeinated teas contribute fluid with negligible caffeine. Any mild diuretic effect from caffeine is generally offset by the water the drink provides, and habitual drinkers show little net loss. Guidance from Harvard's Nutrition Source and WHO frames water as the preferred everyday drink while treating unsweetened tea as a reasonable contributor. Added sugar or honey changes the calorie picture without removing the hydrating water.
Observational research associates moderate coffee intake with lower risk of several conditions, including type 2 diabetes and some liver and cardiovascular outcomes, but most evidence is from cohort studies that show association, not proven cause. Randomized trials are shorter and fewer, and results vary with preparation, added sugar, genetics of caffeine metabolism, and pregnancy status, where lower limits are advised. Cochrane and other reviews caution that confounding and publication bias affect interpretation. Overall, moderate consumption appears safe and possibly beneficial for many adults, yet firm causal claims about specific diseases remain uncertain and are an area of continuing study.
Studies link regular tea drinking, especially green tea, with modest associations to cardiovascular and metabolic measures, but as with coffee the strongest data come from observational cohorts that cannot establish cause. Trial results for green tea extracts do not necessarily reflect ordinary brewed tea, and high-dose supplements have raised separate liver-safety concerns not seen with normal drinking. Cochrane reviews of tea or its catechins report limited or mixed evidence for firm clinical benefits. For most people plain tea is considered a safe part of a healthy pattern, while specific disease-prevention claims remain unproven and require better long-term trials.
Tea is prepared by steeping loose leaves or bags in hot or, for cold-brew and iced versions, cool water, with green teas typically steeped cooler and shorter than black. Water temperature, leaf amount, and steeping time govern how much caffeine and polyphenol is extracted, and over-steeping can increase bitterness and astringency. Some cultures rinse or repeatedly infuse the same leaves, changing successive cups. Additions such as milk, sugar, lemon, or spices modify flavor and, in the case of milk, may bind some polyphenols. Because extraction is so variable, tea's reported nutrient contents are best treated as method-dependent averages.
The caffeine reference does not differ by drink: a single dose up to 200 mg and habitual consumption up to 400 mg a day for non-pregnant adults, 200 mg a day for pregnant women. The figure is set for caffeine from all dietary sources, so tea and coffee spend the same daily allowance rather than each their own. How much caffeine is in a cup of tea depends on brewing — a separate row covers that. Authorities differ on the figure for pregnancy: the body cited here states 200 mg a day, while a 2017 systematic review tested the evidence against Health Canada's figure of 300 mg a day. The difference is between authorities, not an error in this row.
Evidence reviewed: September 3, 2026
Sources are reviewed by the CONTRAST editorial team. External links open in a new tab.