Coffee

What Is Coffee?

Coffee is an evergreen shrub whose roasted seeds make one of the most widely drunk beverages in the world. It is valued above all for caffeine, a stimulant that keeps people awake and alert.

Arabica coffee grows wild in the highland forests of south-western Ethiopia, with smaller populations in South Sudan and northern Kenya, and is now cultivated throughout the tropics ^{40,41Reference 40Davis AP et al. · 2012The impact of climate change on indigenous Arabica coffee (Coffea arabica): predicting future trends and identifying priorities — distribution modellingView study →Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. Its first recorded use as a medicine was in 15th-century Yemen, where Sufi orders drank it to stay awake through night-long ceremonies ^{30Reference 30Jamieson · 2001The Essence of Commodification: Caffeine Dependencies in the Early Modern WorldView study →}.

Besides caffeine, the beans are rich in chlorogenic acids ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}. Large studies that follow people over many years have linked moderate coffee drinking to lower rates of type 2 diabetes, liver disease and early death, though these studies show association rather than cause ^{1,2,3,4,5Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →Reference 3Kim et al. · 2019Meta-analysisCoffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers — meta-analysisView study →Reference 4Crippa et al. · 2014Meta-analysisCoffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysisView study →Reference 5Ding et al. · 2014Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysisView study →}.

Two coffee species dominate the trade. Arabica (Coffea arabica) is the subject of this page; robusta (C. canephora) carries about twice as much caffeine ^{42Reference 42Perrois C et al. · 2015Differential regulation of caffeine metabolism in Coffea arabica (Arabica) and Coffea canephora (Robusta) — plant gene expression studyView study →}.

How Is Coffee Used?

Coffee is drunk mainly to stay awake and focused, and for its taste.

• Filtered coffee — roasted, ground beans brewed in hot water through a paper filter, which holds back most of the diterpenes cafestol and kahweol ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}.
• Unfiltered coffee — espresso, French press and boiled or Turkish coffee, which keep the diterpenes ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}.
• Green coffee bean extract — a concentrated chlorogenic-acid supplement made from unroasted beans, taken in capsules ^{25,26Reference 25Onakpoya et al. · 2011Meta-analysisThe use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trialsView study →Reference 26Samavat et al. · 2024Meta-analysisThe effects of green coffee bean extract on blood pressure and heart rate: a systematic review and dose-response meta-analysis of randomized controlled trialsView study →}.
• Leaf tea — the leaves are sometimes brewed as a tea ^{28Reference 28A modern herbalA modern herbal. (n.d.). Coffee. Retrieved from https://www.botanical.com/botanical/mgmh/c/coffee82.htmlView study →}.

Traditional Uses

Sufi Religious Practice

Coffee originates in Ethiopia, but its first documented medicinal use is Yemeni and religious. By the 15th century it was cultivated in Yemen, and Sufi orders took it as an aid to wakefulness. Their ceremonies ran through the night, and coffee was drunk to sustain the alertness and trance states those rituals required ^{30Reference 30Jamieson · 2001The Essence of Commodification: Caffeine Dependencies in the Early Modern WorldView study →}.

The Arab Coffeehouse

Within about a century coffee had spread across the Arab world, and it travelled through the coffeehouse rather than through religion. Coffeehouses became places to meet and talk over a drink, and they were exclusively male. By the end of the 17th century Cairo was the central coffee market of the region ^{30Reference 30Jamieson · 2001The Essence of Commodification: Caffeine Dependencies in the Early Modern WorldView study →}.

Early European Medicine

Coffee reached Europe through travellers passing through Arab cities. On arrival it was treated as a therapeutic agent and prescribed rather than enjoyed. Once people acquired the taste it moved into the home, and the European coffeehouse followed the Arab model ^{30Reference 30Jamieson · 2001The Essence of Commodification: Caffeine Dependencies in the Early Modern WorldView study →}.

Indications

• Wakefulness and alertness [brewed coffee; Sufi practice] ⚠Caution: In regular drinkers, controlled studies attribute almost all of the lift in alertness and mood to relief from overnight caffeine withdrawal rather than a gain above normal ³⁸.
• Physical performance [caffeine]
• Altitude sickness and fatigue at high altitude [caffeine; mountaineering use] ⚠Caution: Caffeine is recommended to mountaineers for fatigue and poor concentration at altitude ⁴⁷. The evidence on altitude illness itself comes from mice, in which a low dose of caffeine eased high-altitude pulmonary oedema ⁴⁸.
• Asthma, as a mild bronchodilator [caffeine]
• Mild diuretic [caffeine] ⚠Caution: Only large doses, at least 250–300 mg of caffeine (2–3 cups), raise urine output, and mainly in people who have gone days or weeks without it. Regular drinkers become tolerant to the effect ⁴⁵.
• Type 2 diabetes prevention [brewed coffee, caffeinated or decaffeinated]
• Liver disease prevention, including fatty liver, and liver cancer prevention, including in people with hepatitis B or C [brewed coffee] ⚠Caution: A pooled analysis of genetic (Mendelian randomisation) studies found no causal effect on liver cancer ⁷, while a wider review of genetic studies rated a protective effect as probable ⁶.
• Parkinson’s disease prevention [caffeine]
• Cognitive decline and dementia prevention [brewed coffee] ⚠Caution: Genetic studies link higher coffee intake with smaller grey-matter volume and a probable increase in Alzheimer’s risk, the opposite of the cohort findings ⁶.
• Depression prevention [brewed coffee]
• Blood pressure [habitual coffee; green coffee extract] ⚠Caution: A single cup raises blood pressure in people unused to caffeine. Habitual drinkers show no rise, and the lowering effect comes from trials of concentrated green-coffee extract ^16,26.
• Weight and metabolism [caffeine; green coffee extract] ⚠Caution: Green-coffee-extract trials found small weight losses, but the trials were small, short and weak ²⁵.

Botany

Arabica coffee is an evergreen shrub or small tree in the madder family (Rubiaceae) ^{41,44Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}. It can reach 5–8 m, but in cultivation it is usually kept as a compact shrub of 1.5–3 m ^{41,44Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

The leaves are elliptic, 6–14 cm long, with a long pointed tip, and their edges are sometimes wavy ^{41Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. The white, funnel-shaped flowers have five lobes and grow in small clusters of two to five in the leaf axils ^{41Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. They are self-fertile, and honeybees also visit them ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

The fruit is a red, oval to round drupe 11–16 mm long, called a coffee cherry ^{41Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. The seeds inside are the coffee beans.

Arabica is a tetraploid, the product of an ancient hybridisation between C. canephora (robusta) and C. eugenioides ^{39,41Reference 39Davis AP et al. · 2019High extinction risk for wild coffee species and implications for coffee sector sustainability — IUCN Red List assessmentView study →Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. Robusta beans carry about twice as much caffeine as arabica ^{42Reference 42Perrois C et al. · 2015Differential regulation of caffeine metabolism in Coffea arabica (Arabica) and Coffea canephora (Robusta) — plant gene expression studyView study →}.

Distribution

Arabica coffee grows wild in the highland forests of south-western Ethiopia, which hold the largest and most varied populations. Smaller populations grow on the Boma Plateau in south-eastern South Sudan and on Mt Marsabit in northern Kenya, at about 950–1,950 m ^{40Reference 40Davis AP et al. · 2012The impact of climate change on indigenous Arabica coffee (Coffea arabica): predicting future trends and identifying priorities — distribution modellingView study →}. It is cultivated throughout the tropics ^{41Reference 41Chen T et al. · 2011Coffea arabica Linnaeus — species description and distribution — floraView study →}. Near the equator it is grown at 1,300–2,800 m, most often at 1,500–1,900 m ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

The wild species is assessed as Endangered on the IUCN Red List ^{39Reference 39Davis AP et al. · 2019High extinction risk for wild coffee species and implications for coffee sector sustainability — IUCN Red List assessmentView study →}. Climate modelling predicts that the area climatically suitable for wild arabica will shrink by 38% to about 90% by 2080 ^{40Reference 40Davis AP et al. · 2012The impact of climate change on indigenous Arabica coffee (Coffea arabica): predicting future trends and identifying priorities — distribution modellingView study →}.

Sourcing: coffee in a cup or a supplement comes from farmed plants, not from wild trees. The wild populations matter because they hold far more genetic diversity than the cultivated varieties ^{40Reference 40Davis AP et al. · 2012The impact of climate change on indigenous Arabica coffee (Coffea arabica): predicting future trends and identifying priorities — distribution modellingView study →}. Most Ethiopian coffee is shade-grown, and forest and semi-forest coffee is produced in the same area as the wild populations ^{40Reference 40Davis AP et al. · 2012The impact of climate change on indigenous Arabica coffee (Coffea arabica): predicting future trends and identifying priorities — distribution modellingView study →}. Buyers who want to support the wild gene pool can look for Ethiopian forest-grown coffee.

Growing Conditions

Cultivation snapshot for Coffee

ZoneUSDA 10–12Lifetender evergreen perennial, frost-sensitive

Sunlight shade — classically an understorey crop, though also sun-grown in plantations ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

Waterbest with 1,400–2,300 mm of rain a year, and one to two drier months to trigger even flowering ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

Temperaturebest at 14–28 °C ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

Soildeep, friable soil, pH 5.5–7 ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}.

Grow it yourself

Farm Wiki is our cultivation-focused sister site, also run by Justin Cooke.

How to growComing soon

Find seedsComing soon

Harvesting, Collection & Preparation

Coffee plants begin to bear 2–3 years after planting and reach full bearing at 6–8 years ^{44Reference 44Fern · 2024Coffea arabica — habit, range, habitat, cultivation and uses — species databaseView study →}. Flavour varies with the growing region, altitude, soil and growing methods, and it can vary widely within a single region.

After harvest the beans are dried and roasted. Roasting changes the chemistry of the seed: it breaks down part of the chlorogenic acids and trigonelline and forms melanoidins and the compounds behind coffee’s aroma ^{21,31Reference 21Ludwig et al. · 2014ReviewCoffee: biochemistry and potential impact on health — reviewView study →Reference 31Lang et al. · 2013Bioappearance and pharmacokinetics of bioactives upon coffee consumptionView study →}.

Coffee is one of several caffeine plants, alongside yerba maté, tea and guarana.

Pharmacology & Research

Coffee has one of the largest human evidence bases of any plant: hundreds of prospective cohorts, dozens of meta-analyses, and two 2017 umbrella reviews mapping roughly 200 outcomes ^{1,2Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →}.

Moderate habitual intake, around 3–4 cups a day, is associated with lower all-cause and cardiovascular mortality and lower risk of type 2 diabetes, several cancers, Parkinson’s disease and chronic liver disease. The curve is J-shaped, with a clear ceiling ^{1,2,3,4Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →Reference 3Kim et al. · 2019Meta-analysisCoffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers — meta-analysisView study →Reference 4Crippa et al. · 2014Meta-analysisCoffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysisView study →}. The strongest association is with diabetes: 28 cohorts, 1.1 million people, with risk falling about 9% per cup per day for caffeinated and decaffeinated coffee alike ^{5Reference 5Ding et al. · 2014Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysisView study →}.

Genetic (Mendelian randomisation) studies agree with some of these findings and not others. They support protection against liver cancer in one review and not in another, and they point towards higher, not lower, risk for type 2 diabetes and Alzheimer’s disease ^{6,7Reference 6Pham et al. · 2025Systematic reviewCoffee and health outcomes: a systematic review of Mendelian randomisation studies — systematic reviewView study →Reference 7Choi et al. · 2026Meta-analysisCoffee and the risk of hepatocellular carcinoma: a systematic review and meta-analysis of Mendelian randomization studiesView study →}.

Unfiltered coffee raises LDL cholesterol through cafestol and kahweol, and a paper filter removes them.

1. Type 2 Diabetes Prevention

A meta-analysis of 28 prospective cohorts (1,109,272 participants, 45,335 cases) found relative risk falling stepwise with intake — 0.92, 0.85, 0.79, 0.75, 0.71 and 0.67 for one through six cups a day versus none ^{5Reference 5Ding et al. · 2014Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysisView study →}.

Protection held for both caffeinated (RR 0.91 per cup/day) and decaffeinated coffee (RR 0.94), pointing at chlorogenic acid and other components rather than caffeine ^{5Reference 5Ding et al. · 2014Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysisView study →}. Both umbrella reviews rate it among the highest-confidence coffee associations ^{1,2Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →}. A review of Mendelian randomisation studies found probable evidence for a higher genetic risk of type 2 diabetes with coffee intake ^{6Reference 6Pham et al. · 2025Systematic reviewCoffee and health outcomes: a systematic review of Mendelian randomisation studies — systematic reviewView study →}.

Gap: no specific compound or dose has been established, and no long-term randomised trial has been run, so the causal claim rests on cohorts.

2. All-Cause & Cardiovascular Mortality

Large meta-analyses converge on a J-shaped curve. Pooling 40 studies (3.85 million subjects, 450,256 deaths), lowest risk fell at ~3.5 cups/day for all-cause mortality (RR 0.85), 2.5 cups/day for CVD mortality (RR 0.83) and 2 cups/day for cancer mortality (RR 0.96) ^{3Reference 3Kim et al. · 2019Meta-analysisCoffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers — meta-analysisView study →}. An earlier meta of 21 studies put the largest reductions at 4 cups/day (16% lower) and 3 cups/day for CVD mortality (21% lower) ^{4Reference 4Crippa et al. · 2014Meta-analysisCoffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysisView study →}. Decaf preserves the association ^{19Reference 19Li et al. · 2019Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of all-cause mortality: a dose-response meta-analysis of cohort studiesView study →}.

A 2026 meta-analysis of cardiovascular outcomes found no significant association with total coronary heart disease or heart failure at the highest-versus-lowest contrast, and a positive association with myocardial infarction ^{20Reference 20Shaban et al. · 2026Meta-analysisCoffee, caffeine, and cardiovascular health: navigating risks and benefits — an updated systematic review and meta-analysisView study →}.

Entirely observational, with residual confounding by smoking and socioeconomic status hard to exclude, and endpoint-specific results for myocardial infarction and coronary disease inconsistent.

3. Hepatoprotective (Liver Disease / HCC)

A meta-analysis found each extra two cups a day associated with 35% lower hepatocellular carcinoma risk (RR 0.65), unaltered by stage of liver disease, alcohol, BMI, diabetes, smoking or hepatitis B/C, and present though weaker for decaf ^{8Reference 8Kennedy et al. · 2017Meta-analysisCoffee, including caffeinated and decaffeinated coffee, and the risk of hepatocellular carcinoma: a systematic review and dose-response meta-analysisView study →}. Umbrella reviews add lower risk of fatty liver disease and fibrosis ^{9Reference 9Kositamongkol et al. · 2021Meta-analysisCoffee consumption and non-alcoholic fatty liver disease: an umbrella review and a systematic review and meta-analysis — reviewView study →}.

A 2026 meta-analysis of five Mendelian-randomisation studies found no significant causal effect on HCC (IVW odds ratio 0.92, CI 0.58–1.47) and concluded the observational protection was probably overestimated ^{7Reference 7Choi et al. · 2026Meta-analysisCoffee and the risk of hepatocellular carcinoma: a systematic review and meta-analysis of Mendelian randomization studiesView study →}. A 2025 systematic review of Mendelian randomisation studies rated the evidence for protection against HCC as probable ^{6Reference 6Pham et al. · 2025Systematic reviewCoffee and health outcomes: a systematic review of Mendelian randomisation studies — systematic reviewView study →}.

Gap: cohort and genetic studies do not agree on whether coffee protects the liver, so a causal effect is not established.

4. Parkinson’s Disease (Risk Reduction)

A dose-response meta-analysis (13 coffee studies, ~902,000 participants) found a non-linear relationship with maximal protection near 3 cups/day (smoking-adjusted RR 0.72), and a linear 17% risk reduction per 200 mg/day of caffeine ^{10Reference 10Qi et al. · 2014Meta-analysisDose-response meta-analysis on coffee, tea and caffeine consumption with risk of Parkinson’s disease — meta-analysisView study →}.

A 2020 meta-analysis of 13 studies confirmed lower PD risk in regular caffeine consumers (HR ~0.80) and suggested slower progression ^{11Reference 11Hong et al. · 2020Meta-analysisThe effect of caffeine on the risk and progression of Parkinson’s disease: a meta-analysisView study →}.

The protection is stronger in men, and it fits caffeine’s adenosine A2A-receptor antagonism, which is neuroprotective in dopaminergic models ^{1,10Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 10Qi et al. · 2014Meta-analysisDose-response meta-analysis on coffee, tea and caffeine consumption with risk of Parkinson’s disease — meta-analysisView study →}.

The data are observational, and reverse causation is possible: early Parkinson’s reduces the enjoyment of coffee, which could produce this association on its own.

5. Antioxidant

For many populations coffee is the single largest dietary source of antioxidants. Green beans contain about 5–12% chlorogenic acids by dry weight ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}.

Roasting degrades some of that while generating radical-scavenging melanoidins in its place, and brewed coffee retains high, bioavailable capacity ^{21Reference 21Ludwig et al. · 2014ReviewCoffee: biochemistry and potential impact on health — reviewView study →}.

Chlorogenic acid and its metabolites may contribute to the vascular and metabolic findings through improved nitric-oxide availability ^{21Reference 21Ludwig et al. · 2014ReviewCoffee: biochemistry and potential impact on health — reviewView study →}.

High antioxidant capacity in vitro is a chemical property, not a clinical outcome, and there are no antioxidant trials with disease endpoints.

6. Cognitive Decline / Dementia

A meta-analysis of 33 studies (389,505 participants) linked coffee to lower risk of cognitive disorders overall (RR 0.73), peaking near 2.5 cups/day for Alzheimer’s (RR 0.74) and stronger in men ^{13Reference 13Zhu et al. · 2024Meta-analysisModerate coffee or tea consumption decreased the risk of cognitive disorders: an updated dose-response meta-analysisView study →}. A cohort meta-analysis of tea, coffee and caffeine reached similar conclusions ^{14Reference 14Li et al. · 2024Meta-analysisTea, coffee, and caffeine intake and risk of dementia and Alzheimer’s disease: a systematic review and meta-analysis of cohort studiesView study →}; an older review found mixed results ^{22Reference 22Santos et al. · 2010Meta-analysisCaffeine intake and dementia: systematic review and meta-analysisView study →}.

A systematic review of Mendelian randomisation studies found coffee intake associated with smaller grey-matter volume in one study, and probable evidence for an increased risk of Alzheimer’s disease ^{6Reference 6Pham et al. · 2025Systematic reviewCoffee and health outcomes: a systematic review of Mendelian randomisation studies — systematic reviewView study →}.

Gap: the cohort data and the genetic analyses point in opposite directions.

7. Depression (Lower Risk)

A dose-response meta-analysis found a pooled RR of 0.76 for coffee and 0.72 for caffeine versus lowest intake, with risk falling about 8% per cup/day in the linear model ^{12Reference 12Wang et al. · 2016Meta-analysisCoffee and caffeine consumption and depression: a meta-analysis of observational studiesView study →}.

An independent meta-analysis of observational studies reached the same direction of effect ^{23Reference 23Grosso et al. · 2016Meta-analysisCoffee, tea, caffeine and risk of depression: a systematic review and dose-response meta-analysis of observational studiesView study →}.

Proposed mechanisms include caffeine’s adenosine antagonism and coffee polyphenols’ anti-inflammatory and neuroprotective actions ^{12Reference 12Wang et al. · 2016Meta-analysisCoffee and caffeine consumption and depression: a meta-analysis of observational studiesView study →}.

Cross-sectional and cohort data only, with reverse causation a serious concern: depression itself reduces coffee consumption.

8. Blood Pressure / Hypertension

Caffeine causes an acute rise in blood pressure, while habitual moderate intake is neutral to protective. A meta-analysis found no increased hypertension risk at 1–2 cups/day and a small protective association from 3 cups upward (RR 0.97) ^{16Reference 16D’Elia et al. · 2019Meta-analysisCoffee consumption and risk of hypertension: a dose-response meta-analysis of prospective studiesView study →}; a 2023 cohort meta-analysis found ~7% lower risk at highest-versus-lowest intake ^{24Reference 24Haghighatdoost et al. · 2023Meta-analysisCoffee consumption and risk of hypertension in adults: systematic review and meta-analysisView study →}.

The lowering is attributed largely to chlorogenic acid: trials of chlorogenic-acid-rich green-coffee extract show modest reductions in systolic (−2.95 mmHg) and diastolic (−2.15 mmHg) pressure ^{25,26Reference 25Onakpoya et al. · 2011Meta-analysisThe use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trialsView study →Reference 26Samavat et al. · 2024Meta-analysisThe effects of green coffee bean extract on blood pressure and heart rate: a systematic review and dose-response meta-analysis of randomized controlled trialsView study →}.

Gap: a single cup raises blood pressure acutely in someone unaccustomed to it, while habitual drinkers show no elevation. The supporting RCTs also used concentrated green-coffee extract rather than brewed coffee.

9. Cognitive & Athletic Performance (Acute)

Caffeine improves physical performance. It blocks adenosine receptors, improves calcium handling in skeletal muscle and lowers perceived exertion ^{2Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →}.

A review of controlled studies concluded that in habitual users, the apparent gains in alertness and mood after caffeine are almost wholly the reversal of overnight withdrawal. Modest effects may occur on first use, but tolerance develops with regular intake ^{38Reference 38James JE et al. · 2005ReviewEffects of caffeine on performance and mood: withdrawal reversal is the most plausible explanation — reviewView study →}.

Gap: the benefits are acute and depend on the timing of the dose, not a lasting change.

10. Weight / Metabolic (Thermogenesis)

Caffeine acutely stimulates thermogenesis and lipolysis (raising plasma free fatty acids) and increases satiety, effects amplified by chlorogenic acid ^{2Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →}. Green-coffee-extract trials show small weight reductions, but the systematic review judged the trials small, short and methodologically weak ^{25Reference 25Onakpoya et al. · 2011Meta-analysisThe use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trialsView study →}.

Tolerance to the thermogenic effect develops with habitual intake.

Mechanisms

Caffeine blocks adenosine A1 and A2A receptors ^{1,10Reference 1Poole et al. · 2017Meta-analysisCoffee consumption and health: umbrella review of meta-analyses of multiple health outcomes — systematic reviewView study →Reference 10Qi et al. · 2014Meta-analysisDose-response meta-analysis on coffee, tea and caffeine consumption with risk of Parkinson’s disease — meta-analysisView study →}, and regular use leads to tolerance ^{38Reference 38James JE et al. · 2005ReviewEffects of caffeine on performance and mood: withdrawal reversal is the most plausible explanation — reviewView study →}. It has been studied for alertness, blood pressure, thermogenesis, athletic performance and Parkinson’s disease.

Caffeine is chemically related to the asthma drug theophylline and is a weak bronchodilator. In seven small crossover trials in 75 people with mild to moderate asthma, it improved lung function modestly for up to four hours ^{46Reference 46Welsh et al. · 2010Systematic reviewCaffeine for asthma — systematic review of randomised crossover trialsView study →}. Large doses also raise urine output for a short time in people not used to caffeine, an effect that fades with regular intake ^{45Reference 45Maughan et al. · 2003ReviewCaffeine ingestion and fluid balance: a review — reviewView study →}.

The chlorogenic acids have been studied for their effects on glucose handling, blood vessels and the liver, and decaffeinated coffee shares the diabetes association ^{5,21Reference 5Ding et al. · 2014Meta-analysisCaffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and dose-response meta-analysisView study →Reference 21Ludwig et al. · 2014ReviewCoffee: biochemistry and potential impact on health — reviewView study →}. The diterpenes cafestol and kahweol raise LDL cholesterol, and a paper filter holds back most of them ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}.

Clinical Trials

Coffee’s evidence rests on very large observational cohorts and their meta-analyses rather than registered trials. Short-term RCTs exist for blood pressure, lipids, performance and green-coffee-extract weight loss, but long-term disease endpoints cannot ethically be randomised. Mendelian randomisation studies serve as a check on causality.

Last checked: July 2026.

Phytochemistry

The green seed of Coffea arabica contains caffeine at about 0.4–2.5% ^{29,34Reference 29Barceloux · 2012Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive PlantsReference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals} and chlorogenic acids at about 5–12% of dry weight ^{43Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}. It also carries the pyridine alkaloid trigonelline ^{31Reference 31Lang et al. · 2013Bioappearance and pharmacokinetics of bioactives upon coffee consumptionView study →} and the oily diterpenes cafestol and kahweol ^{37Reference 37Juwita et al. · 2025ReviewThe changes of kahweol and cafestol of arabica coffee from bean to consumption: A systematic literature reviewView study →}.

“Chlorogenic acid” is a family rather than a molecule. Each member is one or more caffeic acids esterified to a quinic acid core, and the three mono-esters differ only in which hydroxyl carries the caffeoyl group: chlorogenic acid proper (5-CQA, the dominant one), neochlorogenic acid (3-CQA) and cryptochlorogenic acid (4-CQA). Attaching a second caffeic acid gives the dicaffeoylquinic acids, led by 3,5-dicaffeoylquinic acid. Green coffee beans hold a large variety of these esters ^{36Reference 36Teas et al. · 2011Hoboken: Wiley-Blackwell}.

Roasting changes the mix. Chlorogenic acids break down into caffeoyl quinides, caffeic acid and catechol, and trigonelline breaks down into N-methylpyridinium and niacin, though about 5.3 mg/g of trigonelline remains even in dark-roasted espresso beans. Caffeine is heat-stable and survives roasting largely intact ^{31Reference 31Lang et al. · 2013Bioappearance and pharmacokinetics of bioactives upon coffee consumptionView study →}. Roasting also forms the melanoidins ^{21Reference 21Ludwig et al. · 2014ReviewCoffee: biochemistry and potential impact on health — reviewView study →}.

In the plant, caffeine is made from xanthosine through 7-methylxanthine and theobromine ^{29Reference 29Barceloux · 2012Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive Plants}. The seeds also contain theobromine and theophylline in amounts that vary between species ^{29Reference 29Barceloux · 2012Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive Plants}. In Coffea liberica the main purine alkaloids differ, and include theacrine and liberine ^{29Reference 29Barceloux · 2012Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive Plants}.

Caffeine content also differs between species and plant parts. Robusta (C. canephora) beans carry about twice the caffeine of arabica, and in both species the young leaves hold more caffeine than the maturing beans ^{42Reference 42Perrois C et al. · 2015Differential regulation of caffeine metabolism in Coffea arabica (Arabica) and Coffea canephora (Robusta) — plant gene expression studyView study →}. Caffeine also occurs in tea, guarana and yerba maté ^{35Reference 35Schimpl et al. · 2013Guarana: Revisiting a highly caffeinated plant from the AmazonView study →}.

Figures for green beans, roasted beans and brewed coffee are measured differently and do not compare directly.

Constituent Summary

Figures are for Coffea arabica seeds, green unless noted.

Dosage

In the research the dose is the beverage itself, measured in cups per day. The green-coffee-extract row is a concentrated chlorogenic-acid supplement and does not correspond to cups of brewed coffee.

Traditional Dosage

Safety & Pregnancy

Coffee is safe for most adults at moderate habitual intake, about 3–4 cups a day ^{3,4Reference 3Kim et al. · 2019Meta-analysisCoffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers — meta-analysisView study →Reference 4Crippa et al. · 2014Meta-analysisCoffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysisView study →}. Its cautions come from caffeine’s effects on the heart and nervous system, from the diterpenes in unfiltered brews, from drug interactions, and from pregnancy.

Full Safety & Interactions Detail

Heart and nervous system. Caffeine causes an acute rise in blood pressure and can provoke anxiety, insomnia, palpitations and, at high doses, arrhythmia in susceptible people. Tolerance to the rise in blood pressure develops with regular use ^{2,16Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →Reference 16D’Elia et al. · 2019Meta-analysisCoffee consumption and risk of hypertension: a dose-response meta-analysis of prospective studiesView study →}.

Unfiltered coffee. Espresso, French press and boiled or Turkish coffee raise LDL cholesterol, because a paper filter is needed to remove the diterpenes cafestol and kahweol ^{2,43Reference 2Grosso et al. · 2017Systematic reviewCoffee, caffeine, and health outcomes: an umbrella review — systematic reviewView study →Reference 43Finta H et al. · 2026ReviewBioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects — A Review — reviewView study →}. This matters for people with high cholesterol.

Drug interactions. Caffeine is broken down mainly by CYP1A2. In eight healthy volunteers, the antidepressant fluvoxamine cut caffeine clearance about fivefold and stretched its half-life from about 5 to 31 hours ^{49Reference 49Jeppesen et al. · 1996A fluvoxamine-caffeine interaction study — clinical pharmacokinetic studyView study →}.

In healthy volunteers, the antibiotic ciprofloxacin roughly doubled blood levels of caffeine ^{50Reference 50Mahr et al. · 1992Effects of temafloxacin and ciprofloxacin on the pharmacokinetics of caffeine — clinical pharmacokinetic studyView study →}. Women taking oral contraceptives cleared caffeine more slowly, with a half-life of about 11 hours against 6 ^{51Reference 51Patwardhan et al. · 1980Impaired elimination of caffeine by oral contraceptive steroids — clinical pharmacokinetic studyView study →}.

Caffeine also adds to the effects of theophylline and other stimulants.

Withdrawal. Stopping abruptly produces a recognised withdrawal syndrome of headache, fatigue and low mood.

References

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