{ "id": "whats-in-a-cup-of-coffee", "url": "https://coffearium.org/entries/whats-in-a-cup-of-coffee/", "license": "CC-BY-4.0", "title": "What’s in a cup of coffee", "summary": "A cup of black coffee is almost all water. The rest – about 1–2% in filter coffee – holds caffeine, chlorogenic acids, melanoidins, minerals and traces of niacin. What the published figures say per cup, and what they mean.", "domain": "science", "kind": "Concept", "stage": "cup", "topics": [ "science" ], "topicSections": {}, "lang": "en", "status": "verified", "reviewer": "Coffearium verification pass", "lastVerified": "2026-10-21T00:00:00.000Z", "updated": "2026-10-21T00:00:00.000Z", "added": "2026-10-21T00:00:00.000Z", "brief": [ "Filter coffee in the Golden Cup range is 1.15–1.35% dissolved solids, so 98.65–98.85% water (our calculation); three espresso recipes in one study held 3.32–8.44%.1,3", "A 2014 review reports 7–24 mg magnesium, 34–116 mg potassium and 1–3 mg nicotinic acid (niacin) per cup.5", "Against EU reference intakes, that is about 2–6% of magnesium and potassium and 6–19% of niacin per cup (our calculation).5,9", "Per serving, the same review gives 40–110 mg trigonelline, and 24–423 mg chlorogenic acids in espresso.5", "Swiss dietary recommendations (2024) state that caffeinated drinks such as coffee can contribute to fluid intake.12" ], "quickFacts": [ { "label": "Water, filter coffee", "value": "98.65–98.85% (our calculation from 1.15–1.35% TDS)" }, { "label": "Dissolved solids, espresso", "value": "3.32–8.44% (one study, three recipes)" }, { "label": "Magnesium per cup", "value": "7–24 mg (review)" }, { "label": "Potassium per cup", "value": "34–116 mg (review)" }, { "label": "Nicotinic acid (niacin) per cup", "value": "1–3 mg (review)" }, { "label": "Trigonelline per serving", "value": "40–110 mg (review)" }, { "label": "Melanoidins", "value": "About 29% of the brew’s dry matter (review)" }, { "label": "“A cup”", "value": "Not a defined volume" } ], "aka": [ "Coffee composition", "Nutrients in coffee", "Coffee nutrition" ], "linkTerms": [ "nutrients in coffee", "coffee nutrition", "composition of brewed coffee", "coffee and hydration" ], "related": [ "caffeine", "chlorogenic-acids", "coffee-oil", "melanoidins", "acids-in-coffee", "carbohydrates-and-body", "extraction-yield-and-tds", "bioactive-compounds", "coffee-and-digestion", "contaminants-and-food-safety", "coffee-and-long-term-health", "how-to-read-coffee-health-news", "decaffeination" ], "contested": [ "Melanoidins per cup: a 2014 review states that melanoidins make up around 29% of the dry matter of coffee brew5, which for a 150 g filter cup at 1.15–1.35% TDS would be about 0.5–0.6 g (our calculation). A 2011 paper compiling eight studies of filter brew reports 0.25–0.81 g per 100 mL6, about 0.4–1.2 g in 150 mL (our calculation). The studies isolated high-molecular-weight material by different methods (dialysis, ultrafiltration, gel filtration), and the paper notes that dialysis can raise the apparent amount.6 At the upper end, 1.2 g would be about 60–70% of the dissolved solids of a Golden Cup filter cup, far above the review’s 29% (our calculation).1,5,6", "Share of the daily requirement per cup: our calculation against the EU reference intakes gives about 2–6% for magnesium and potassium5,9; a 2021 review, using its own reference values and serving sizes, gives 6.4–7.5% for magnesium and 6.6% for potassium.8 The figures differ because they use different reference values, serving sizes and brew data." ], "corrections": [ { "date": "2026-10-21T00:00:00.000Z", "change": "Espresso dissolved solids now give all three espresso recipes of the study (3.32%, 5.20% and 8.44%), not two.", "reason": "The study's table lists a third espresso recipe at 3.32% TDS; quoting only two overstated espresso strength." }, { "date": "2026-10-21T00:00:00.000Z", "change": "Melanoidin contested item now quantifies the gap (upper estimate about 60–70% of filter-cup dissolved solids against the review's 29%) and names the isolation methods; daily intake given as the paper's order-of-magnitude estimate.", "reason": "The previous wording (\"approach the total dissolved solids\") overstated the comparison." }, { "date": "2026-10-21T00:00:00.000Z", "change": "Swiss recommendation on preferred drinks reworded to water first, then herbal and fruit teas.", "reason": "The source does not name \"unsweetened teas\" in general as preferred drinks." } ], "sources": [ { "id": "s1", "title": "Brew temperature, at fixed brew strength and extraction, has little impact on the sensory profile of drip brew coffee", "authors": "Batali, M. E.; Ristenpart, W. D.; Guinard, J.-X.", "year": 2020, "publisher": "Scientific Reports 10, 16450", "url": "https://www.nature.com/articles/s41598-020-73341-4", "doi": "10.1038/s41598-020-73341-4", "tier": "A", "quote": "The chart’s central region, which spans TDS values of 1.15–1.35% and PE values of 18–22%, is denoted as “ideal”", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s2", "title": "Comparison of nine common coffee extraction methods: instrumental and sensory analysis", "authors": "Gloess, A. N.; Schönbächler, B.; Klopprogge, B.; D’Ambrosio, L.; Chatelain, K.; Bongartz, A.; Strittmatter, A.; Rast, M.; Yeretzian, C.", "year": 2013, "publisher": "European Food Research and Technology 236, 607–627", "url": "https://digitalcollection.zhaw.ch/bitstream/11475/4251/2/2013_Gloess-etal_Comparison-of-nine-common-coffee-extraction-methods.pdf", "doi": "10.1007/s00217-013-1917-x", "tier": "A", "quote": "The extraction efficiency of caffeine was comparable to that of total solids, with the exception of filter coffee.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s3", "title": "What kind of coffee do you drink? An investigation on effects of eight different extraction methods", "authors": "Angeloni, G.; Guerrini, L.; Masella, P.; Bellumori, M.; Daluiso, S.; Parenti, A.; Innocenti, M.", "year": 2019, "publisher": "Food Research International, pp. 1327–1335 (volume not confirmed in the copies opened)", "url": "https://flore.unifi.it/bitstream/2158/1142622/5/Angeloni%20et%20al_Food%20Research%20International_2018-in%20Press.pdf", "doi": "10.1016/j.foodres.2018.10.022", "tier": "A", "quote": "Maximum caffeine and CGA concentrations were found in Espresso coffees", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s4", "title": "Influence of Flow Rate, Particle Size, and Temperature on Espresso Extraction Kinetics", "authors": "Schmieder, B. K. L.; Pannusch, V. B.; Vannieuwenhuyse, L.; Briesen, H.; Minceva, M.", "year": 2023, "publisher": "Foods 12(15), 2871", "url": "https://mdpi-res.com/d_attachment/foods/foods-12-02871/article_deploy/foods-12-02871.pdf", "doi": "10.3390/foods12152871", "tier": "A", "quote": "The fastest decrease was observed for trigonelline and Total Dissolved Solids (TDS), followed by 5-caffeoylquinic acid (5-CQA) and caffeine.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s5", "title": "Coffee: biochemistry and potential impact on health", "authors": "Ludwig, I. A.; Clifford, M. N.; Lean, M. E. J.; Ashihara, H.; Crozier, A.", "year": 2014, "publisher": "Food & Function 5(8), 1695–1717", "url": "https://pubs.rsc.org/zh-tw/content/getauthorversionpdf/C4FO00042K", "doi": "10.1039/C4FO00042K", "tier": "A", "quote": "one cup of coffee provides 7-24 mg of magnesium and 34-116 mg of potassium per cup of coffee.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s6", "title": "Estimation of dietary intake of melanoidins from coffee and bread", "authors": "Fogliano, V.; Morales, F. J.", "year": 2011, "publisher": "Food & Function 2(2), 117–123", "url": "https://pubs.rsc.org/en/content/articlehtml/2011/fo/c0fo00156b", "doi": "10.1039/c0fo00156b", "tier": "A", "quote": "It is known that the darker the roasting degree, the higher the amount of melanoidins", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s7", "title": "Espresso coffees, caffeine and chlorogenic acid intake: potential health implications", "authors": "Crozier, T. W. M.; Stalmach, A.; Lean, M. E. J.; Crozier, A.", "year": 2012, "publisher": "Food & Function 3(1), 30–33", "url": "https://pubs.rsc.org/en/content/articlehtml/2012/fo/c1fo10240k", "doi": "10.1039/C1FO10240K", "tier": "A", "quote": "The amount of caffeine that a consumer would ingest per serving ranged from 51 to 322 mg", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s8", "title": "Coffee Brews: Are They a Source of Macroelements in Human Nutrition?", "authors": "Olechno, E.; Puścion-Jakubik, A.; Socha, K.; Zujko, M. E.", "year": 2021, "publisher": "Foods 10(6), 1328", "url": "https://doaj.org/article/b88b822943f9403994aaf73a2661b3d5", "doi": "10.3390/foods10061328", "tier": "A", "quote": "Coffee provides slightly lower amounts of phosphorus (up to 2.2%), sodium (up to 2.2%), and calcium (up to 0.7% of the daily requirement for women and 0.6% for men).", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s9", "title": "Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers, Annex XIII: Reference intakes", "authors": "European Parliament; Council of the European Union", "year": 2011, "publisher": "Official Journal of the European Union L 304, 22.11.2011; Annex XIII as published by the Food Safety Authority of Ireland", "url": "https://www.fsai.ie/training/nutrition_labelling/story_content/external_files/ANNEX%20XIII.pdf", "tier": "A", "quote": "7.5 % of the nutrient reference values specified in point 1 supplied by 100ml in the case of beverages or", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s10", "title": "Scientific Opinion on Dietary reference values for water", "authors": "EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA)", "year": 2010, "publisher": "EFSA Journal 8(3), 1459", "url": "https://orbit.dtu.dk/en/publications/efsa-panel-on-dietetic-products-nutrition-and-allergies-nda-scien-153/", "doi": "10.2903/j.efsa.2010.1459", "tier": "A", "quote": "Available data for adults permit the definition of AIs as 2.0 L/day (P 95 3.1 L) for females and 2.5 L/day (P95 4.0 L) for males.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s11", "title": "Caffeine and diuresis during rest and exercise: A meta-analysis", "authors": "Zhang, Y.; Coca, A.; Casa, D. J.; Antonio, J.; Green, J. M.; Bishop, P. A.", "year": 2015, "publisher": "Journal of Science and Medicine in Sport 18(5), 569–574", "url": "https://scholars.nova.edu/en/publications/caffeine-and-diuresis-during-rest-and-exercise-a-meta-analysis/", "doi": "10.1016/j.jsams.2014.07.017", "tier": "A", "quote": "Caffeine exerted a minor diuretic effect which was negated by exercise.", "abstractOnly": true, "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s12", "title": "Schweizer Ernährungsempfehlungen für Erwachsene – Kurzversion", "authors": "Schweizerische Gesellschaft für Ernährung (SGE); Bundesamt für Lebensmittelsicherheit und Veterinärwesen (BLV)", "year": 2024, "publisher": "Federal Food Safety and Veterinary Office (BLV), Bern", "url": "https://www.blv.admin.ch/dam/blv/de/dokumente/lebensmittel-und-ernaehrung/ernaehrung/merkblatt-schweizer-ernaehrungsempfehlung-kurz.pdf.download.pdf/Schweizer%20Ern%C3%A4hrungsempfehlungen_Kurzversion_DE.pdf", "tier": "A", "quote": "Koffeinhaltige Getränke wie Kaffee und Schwarztee können zur Flüssigkeitszufuhr beitragen.", "accessed": "2026-10-21T00:00:00.000Z" }, { "id": "s13", "title": "Scientific Opinion on the safety of caffeine", "authors": "EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)", "year": 2015, "publisher": "EFSA Journal 13(5), 4102", "url": "https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2015.4102", "doi": "10.2903/j.efsa.2015.4102", "tier": "A", "quote": "Habitual caffeine consumption up to 400 mg per day does not give rise to safety concerns for non-pregnant adults.", "accessed": "2026-10-21T00:00:00.000Z" } ], "markdown": "## Mostly water\n\nA cup of black coffee is water with a small amount of coffee dissolved in it. Brewers measure that amount as total dissolved solids (TDS), the share of the drink by weight that is coffee.1 The Golden Cup range for filter coffee is 1.15–1.35% TDS.1 The rest, 98.65–98.85%, is water (our calculation).\n\nEspresso is stronger. In one study, three espresso recipes held 3.32%, 5.20% and 8.44% TDS, against 1.35–1.55% for filter and immersion brews of the same coffee.3 Even the strongest espresso was still about 92% water (our calculation).\n\nStrength and serving size work together. A 150 g cup of filter coffee in the Golden Cup range holds about 1.7–2.0 g of dissolved coffee (our calculation).1 In a laboratory study, a 40 g espresso brewed from 20 g of coffee held 3.88 g.4 In a comparison of nine brew methods, an espresso and a lungo held about the same total solids per cup.2 How strength and extraction are measured is explained in *Extraction yield and TDS*.\n\n## What the dissolved part is made of\n\nThe dissolved part is a mixture of many compound classes. A 2014 review names volatile aroma compounds, alkaloids such as caffeine and trigonelline, chlorogenic acids, diterpenes and melanoidins among the key compounds of the beverage.5 Melanoidins are brown, high-molecular-weight products of roasting. The same review puts them at around 29% of the dry matter of coffee brew.5\n\nCoffee brews also contain carbohydrates that the body does not digest. They are mainly galactomannans and arabinogalactans from the bean’s cell walls.5 Acids, sugars and the other soluble compounds are covered in their own entries: *Acids in coffee*, *Carbohydrates and body*, *Melanoidins* and *Chlorogenic acids*.\n\nHow much of each reaches the cup depends on the coffee, the roast and the brew. The same 2014 review notes that “a cup of coffee” is not a well-defined measurement.5 All per-cup values below are ranges from different studies, not fixed contents.\n\n## Minerals and vitamins\n\nA 2014 review reports that coffee brew contains several micronutrients, including magnesium, potassium and vitamins B3 and E.5 It gives 7–24 mg of magnesium and 34–116 mg of potassium per cup.5 Vitamin B3 forms during roasting, when part of the trigonelline breaks down to nicotinic acid, also called niacin.5 The review cites reports of 1–3 mg of nicotinic acid per cup.5\n\nA 2021 review of studies published between 2000 and 2020 looked at five minerals in coffee brews. It found that coffee is not a significant source of sodium.8 Calcium, phosphorus and sodium per portion each stayed at or below 2.2% of the daily requirement.8\n\nCompared with the EU reference intakes used on food labels, one cup holds roughly 2–6% of the magnesium and potassium and 6–19% of the niacin reference values (our calculation).5,9 The Deep dive shows how these figures were worked out.\n\nEverything in a filter cup that is not water weighs about 2 g (our calculation from the strength above).1 No food composition database could be opened for this entry, so energy values for black coffee and milk drinks are not given here.\n\n## Compounds with effects in the body\n\nSeveral of the dissolved compounds are studied for their effects in the body. Their amounts per cup vary widely:\n\n- **Caffeine.** Espressos bought in 20 cafés held 51–322 mg each.7 The European Food Safety Authority (EFSA) considers habitual intake up to 400 mg a day of no safety concern for non-pregnant adults.13 Details are in *Caffeine*.\n- **Chlorogenic acids.** A single espresso supplies 24–423 mg, according to the 2014 review.5 Roasting breaks them down; see *Chlorogenic acids*.\n- **Trigonelline.** Amounts in brews appear to range between 40 and 110 mg per serving.5\n- **Diterpenes (cafestol and kahweol).** Boiled coffee, French press and Turkish coffee contain 6–12 mg per cup; filter and instant coffee less than 0.6 mg.5 See *Coffee oil*.\n- **Melanoidins.** Around 29% of the dry matter of the brew.5 A 2011 estimate put melanoidin intake from coffee in the order of 1 g a day, reaching about 2 g for heavy drinkers.6\n\nWhat these compounds do in the body is covered in *Bioactive compounds*. What large observational studies have found about coffee drinkers is covered in *Coffee and long-term health*. Unwanted compounds such as acrylamide are covered in *Contaminants and food safety*.\n\n
\n
\n
Amounts per cup or serving reported for selected compounds and minerals, from a 2014 review5 and a survey of 20 café espressos.7 Cup sizes and brews differ between rows; the review does not define a cup volume.
\n
\n\n## Coffee and fluid balance\n\nCoffee is mostly water, and caffeine increases urine output a little. A 2015 meta-analysis pooled 16 studies of caffeine in healthy adults, with a median dose of 300 mg.11 It found a minor diuretic effect, which exercise cancelled out.11 Women showed a larger effect than men, and the effect was larger at rest.11 The studies tested caffeine, not coffee in particular.11\n\nHealth authorities count beverages in total water intake. EFSA’s reference values for water include water from drinking water, beverages of all kinds and food moisture.10 The 2024 Swiss dietary recommendations state that caffeinated drinks such as coffee and black tea can contribute to fluid intake. They recommend moderate consumption and name water first, followed by herbal and fruit teas, among the unsweetened drinks to prefer.12\n\n\n\n## Reference values\n\nValues as reported in the sources, or calculated by us from them where stated. They describe published ranges, not the content of any particular cup.\n\n| Parameter | Value reported | Basis and conditions | Source |\n|---|---|---|---|\n| Dissolved solids, filter (Golden Cup) | 1.15–1.35% TDS | Central region of the brewing control chart | Batali et al.1 |\n| Water, filter (Golden Cup) | 98.65–98.85% | Our calculation: 100% minus TDS | Batali et al.1 |\n| Dissolved solids, espresso | 3.32%, 5.20% and 8.44% | Three espresso recipes, one coffee | Angeloni et al.3 |\n| Dissolved solids, filter and immersion | 1.35–1.55% | V60, AeroPress, French press, cold brew; same coffee | Angeloni et al.3 |\n| Total solids, nine methods | Espresso > 4%; moka pot 2.13%; French press 1.43%; filter 1.03% | One coffee, laboratory comparison | Gloess et al.2 |\n| Dissolved solids in a 40 g espresso | 3.88 g | 20 g dose, centre point; calculated by the authors from fitted curves | Schmieder et al.4 |\n| Dissolved solids in a 150 g filter cup | ≈1.7–2.0 g | Our calculation at 1.15–1.35% TDS | Batali et al.1 |\n| Magnesium | 7–24 mg per cup | Cup volume not stated | Ludwig et al.5 |\n| Potassium | 34–116 mg per cup | Cup volume not stated | Ludwig et al.5 |\n| Potassium, brews | 37.21–154.07 mg per 100 mL | Lowest: ground coffee mixed with water; highest: arabica, AeroPress | Olechno et al.8 |\n| Nicotinic acid (niacin) | 1–3 mg per cup | Reported values cited by the review | Ludwig et al.5 |\n| Trigonelline | 40–110 mg per serving | Brews | Ludwig et al.5 |\n| Trigonelline, espresso | 98.3 mg in 40 g | 20 g dose, centre point; fitted curves | Schmieder et al.4 |\n| Chlorogenic acids, espresso | 24–423 mg per serving | Commercial espressos | Ludwig et al.5 |\n| Caffeine, espresso | 51–322 mg per serving | 20 cafés, Glasgow | Crozier et al.7 |\n| Cafestol and kahweol | 6–12 mg per cup (boiled, French press, Turkish); ≈4 mg (espresso); < 0.6 mg (filter, instant) | Review | Ludwig et al.5 |\n| Melanoidins, share of brew dry matter | ≈29% | Review | Ludwig et al.5 |\n| Melanoidins, filter brew | 0.25–0.81 g per 100 mL | Eight studies, medium roast where available, coffee-to-water ratio 0.050–0.070, different isolation methods | Fogliano & Morales6 |\n| Melanoidin intake from coffee | Order of magnitude 1 g per day; about 2 g for heavy drinkers | Estimate from consumption data | Fogliano & Morales6 |\n| EU reference intakes (adults) | Magnesium 375 mg; potassium 2,000 mg; calcium 800 mg; phosphorus 700 mg; niacin 16 mg | Labelling reference values, Annex XIII Part A | Regulation (EU) No 1169/20119 |\n| “Significant amount”, beverages | 7.5% of the reference value per 100 mL | Labelling rule, Annex XIII | Regulation (EU) No 1169/20119 |\n| Adequate intake of water (total) | 2.0 L/day (women); 2.5 L/day (men) | From drinking water, beverages and food; moderate temperature and activity | EFSA10 |\n| Recommended drinks (Switzerland) | 1–2 L of unsweetened drinks a day | Adults; dietary recommendations 2024 | SGE and BLV12 |\n\n## Per cup, per serving, per 100 mL\n\nPublished values come in three bases, and they are not interchangeable. Concentrations per 100 mL describe the brew; amounts per cup also depend on how big the cup is. The 2014 review notes that “a cup of coffee” is not a well-defined measurement.5 The 2021 mineral review assumed 150 mL for brewed coffee and 30 mL for espresso to estimate one portion.8\n\nStrong brews in small cups and weak brews in large cups can therefore give similar amounts. In the nine-method comparison, an espresso and a lungo held about the same total solids per cup.2 A 40 g espresso held 3.88 g of dissolved solids4, about twice the 1.7–2.0 g of a 150 g filter cup in the Golden Cup range (our calculation).1\n\nThe 2021 review also examined the factors that influence the mineral content of brews, including the brew method.8 How brewing water is specified is covered in *Water for coffee*.\n\n## Reference intakes, our calculation\n\nThe EU sets reference intakes for adults in Annex XIII of Regulation (EU) No 1169/2011. They are used for nutrition labelling: 375 mg for magnesium, 2,000 mg for potassium and 16 mg for niacin.9 Dividing the per-cup values of the 2014 review by these figures gives:\n\n| Nutrient | Per cup (review) | EU reference intake | Share per cup (our calculation) |\n|---|---|---|---|\n| Magnesium | 7–24 mg5 | 375 mg9 | 1.9–6.4% |\n| Potassium | 34–116 mg5 | 2,000 mg9 | 1.7–5.8% |\n| Niacin (nicotinic acid) | 1–3 mg5 | 16 mg9 | 6.3–18.8% |\n\nThe review itself puts the niacin figure at 6–18% of a recommended allowance of 16 mg a day for adult men.5 The 2021 mineral review used its own reference values, including 3,500 mg a day for potassium. With those, it calculated that one portion covers 7.5% (women) or 6.4% (men) of the magnesium requirement and 6.6% of the potassium requirement.8\n\n
\n
\n
Share of the EU reference intake per cup: our calculation from per-cup values in a 2014 review5 and the reference intakes of Regulation (EU) No 1169/20119, with the 2021 mineral review’s own estimates for comparison.8 Ranges, not the content of a particular cup.
\n
\n\nFor labelling, EU law treats 7.5% of the reference value per 100 mL as a “significant amount” in a beverage.9 The potassium range of 37.21–154.07 mg per 100 mL in the 2021 review corresponds to 1.9–7.7% of 2,000 mg per 100 mL (our calculation).8,9 This is a labelling yardstick, not a judgement about health.\n\n## Caffeine and urine output\n\nThe 2015 meta-analysis included 16 studies in healthy adults, giving 28 effect sizes, analysed with a random-effects model.11 Across all of them, caffeine increased urine volume by 109 ± 195 mL compared with conditions without caffeine.11 The effect was larger at rest than during exercise, and larger in women than in men.11 The pooled studies tested caffeine at a median dose of 300 mg, not coffee in particular.11\n\nEFSA’s adequate intakes for water are 2.0 L a day for women and 2.5 L a day for men, from all sources and under moderate temperature and activity.10 No source opened for this entry gives a figure for how much of a cup of coffee counts towards that total.\n\n## Open questions\n\n- **What “a cup” is.** Reviews report per-cup values without a common cup volume, so they cannot be compared directly.5,8\n- **Origin of the mineral range.** The 2014 review gives 7–24 mg of magnesium and 34–116 mg of potassium per cup without naming the underlying studies or cup sizes in that passage.5\n- **Melanoidin quantity.** Isolation methods differ, and published amounts per 100 mL range widely.6\n- **Food composition data.** No national food composition database could be opened for this entry. Energy and macronutrient values for black coffee and milk drinks therefore remain to be added.\n\n## Key studies\n\n
\n

Ludwig et al., 2014 – Coffee: biochemistry and potential impact on health. A review of the compounds in green and roasted coffee and in the brew, and of their absorption and metabolism. It collects per-cup ranges for caffeine, chlorogenic acids, trigonelline, diterpenes, minerals and nicotinic acid, and notes that “a cup” is not a defined measure.

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Food & Function 5(8), 1695–1717 · doi:10.1039/C4FO00042K

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Olechno et al., 2021 – Coffee brews as a source of macroelements. A review of studies from 2000 to 2020 on sodium, potassium, calcium, magnesium and phosphorus in coffee brews made by different methods. Assuming 150 mL for brewed coffee and 30 mL for espresso, the authors estimate that one portion covers 6.4–7.5% of the daily magnesium requirement and 6.6% of the potassium requirement.

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Foods 10(6), 1328 · doi:10.3390/foods10061328

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Zhang et al., 2015 – Caffeine and diuresis. A meta-analysis of 16 studies in healthy adults with a median caffeine dose of 300 mg. Caffeine had a minor diuretic effect that exercise cancelled out; women and people at rest showed larger effects.

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Journal of Science and Medicine in Sport 18(5), 569–574 · doi:10.1016/j.jsams.2014.07.017

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Gloess et al., 2013 – Nine extraction methods compared. Brewed one coffee by nine common methods and compared the brews by instrumental and sensory analysis. Espressos held more than 4% total solids and filter coffee about 1%, yet an espresso and a lungo held similar total solids per cup.

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European Food Research and Technology 236, 607–627 · doi:10.1007/s00217-013-1917-x

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\n\n*General information, not medical advice.*" }