- Coffee and health
Coffeecontains several compounds which are known to affect human body chemistry. The coffee bean itself contains chemicals which are psychotropic (in a way some find pleasing) for humans as a by-product of their defense mechanism. These chemicals are toxic in large doses, or even in their normal amount when consumed by many creatures which may otherwise have threatened the beans in the wild.
Coffee as a stimulant
caffeine, which acts as a stimulant. For this reason, it is often consumed in the morning and during working hours. Students preparing for examinations with late-night "cram sessions" or "code jams" frequently use coffee to keep themselves awake. Many office workers take a "coffee break" when their energy is diminished.
Recent research has uncovered additional stimulating effects of coffee which are not related to its caffeine content. Coffee contains an as yet unknown chemical agent which stimulates the production of
cortisoneand adrenaline, two stimulating hormones.Klag MJ, Wang NY, Meoni LA, Brancati FL, Cooper LA, Liang KY, Young JH, Ford DE. Coffee intake and risk of hypertension: the Johns Hopkins precursors study. "Arch Intern Med" 2002;162:657-62. PMID 11911719.]
For occasions when one wants to enjoy the flavor of coffee with almost no stimulation,
decaffeinated coffee(also called "decaf") is available. This is coffee from which most of the caffeine has been removed, by the Swiss water process(which involves the soaking of raw beans to absorb the caffeine) or the use of a chemical solventsuch as trichloroethylene("tri"), or the more popular methylene chloride, in a similar process. Another solvent used is ethyl acetate; the resultant decaffeinated coffee is marketed as "natural decaf" because ethyl acetate is naturally present in fruit. Extraction with supercritical carbon dioxidehas also been employed.
Decaffeinated coffee usually loses some flavor over normal coffees and tends to be more bitter. There are also coffee alternatives that resemble coffee in taste but contain no caffeine (see below). These are available both in ground form for brewing and in instant form.
Caffeine dependency and
withdrawalsymptoms are well-documented; see Caffeinefor more on the pharmacological effects of caffeine.
Reduced risk of Alzheimer's disease
Several studies comparing moderate coffee drinkers (about 2 cups a day) with light coffee drinkers (less than one cup a day) found that those who drank more coffee were significantly less likely to develop
Alzheimer's diseaselater in life. [Maia, L., & de Mendonça, A., Does caffeine intake protect from Alzheimer's disease?, "European Journal of Neurology", July 2002, 9:4, 377 ( [http://www.blackwell-synergy.com/links/doi/10.1046/j.1468-1331.2002.00421.x/full/?cookieSet=1] accessed Nov 30, 2006)] [Lindsay, J., "et al.", Risk Factors for Alzheimer’s Disease: A Prospective Analysis from the Canadian Study of Health and Aging, Am J Epidemiol 2002; 156:445-453, ( [http://aje.oxfordjournals.org/cgi/content/abstract/156/5/445] accessed Nov 30, 2006)]
Reduced risk of gallstone disease
Drinking caffeinated coffee has been correlated with a lower incidence of
gallstones and gallbladderdisease in both men [Leitzmann, W.F., "et al.", A prospective study of coffee consumption and the risk of symptomatic gallstone disease in men, "JAMA" (1999), 281:2106-12] and women [ Leitzmann MF, Stampfer MJ, Willett WC, Spiegelman D, Colditz GA, Giovannucci EL., Coffee intake is associated with lower risk of symptomatic gallstone disease in women, "Gastroenterology", 2002 Dec;123(6):1823-30] in two studies performed by the Harvard School of Public Health. A lessened risk was not seen in those who drank decaffeinated coffee.
Reduced risk of Parkinson's disease
A study comparing heavy coffee drinkers (3.5 cups a day) with non-drinkers found that the coffee drinkers were significantly less likely to contract
Parkinson's Diseaselater in life. [Webster Ross, G. "et al.", Association of Coffee and Caffeine Intake With the Risk of Parkinson Disease, "JAMA", May 24, 2000, 283:20, ( [http://jama.highwire.org/cgi/content/abstract/283/20/2674] accessed Nov 30, 2006)] . Likewise, a second study found an inverse relationship between the amount of coffee regularly drunk and the likelihood of developing Parkinson's Disease. [Benedetti M.D. "et al.", Smoking, alcohol, and coffee consumption preceding Parkinson’s disease, "Neurology", 2000:55, 1350-1358. ( [http://neurology.org/cgi/content/abstract/55/9/1350] accessed Nov 30, 2006)]
Many people drink coffee for its ability to increase short term recall and increase IQ [Koppelstaeter F, Siedentopf C, Poeppel T, Haala I, Ischebeck A, Mottaghy F. Influence of caffeine =excess on activation patterns in verbal working memory. Radiological Society of North America, 2005, abstract no LPR06-05 [http://rsna2005.rsna.org/rsna2005/V2005/conference/event_display.cfm?em_id=4418422 link] .] .
Likewise, in tests of simple reaction time, choice reaction time, incidental verbal memory, and visuospatial reasoning, participants who regularly drank coffee were found to perform better on all tests, with a positive relationship between test scores and the amount of coffee regularly drunk. Elderly participants were found to have the largest effect associated with regular coffee drinking. [Jarvis, M.J., Does caffeine intake enhance absolute levels of cognitive performance?, "Psychopharmacology", 2 December, 2005, 110:1-2, 45-52. ( [http://www.springerlink.com/content/y414x83288221635/] accessed Nov 30, 2005).] Another study found that women over the age of 80 performed significantly better on cognitive tests if they had regularly drank coffee over their lifetimes. [Johnson-Kozlow, M., "et al.", Coffee Consumption and Cognitive Function among Older Adults, "Am J Epidemiol" 2002; 156:842-850 ( [http://aje.oxfordjournals.org/cgi/content/abstract/156/9/842] accessed Nov 30, 2006)]
Coffee contains caffeine, which increases the effectiveness of
pain killers, especially migraineand headache medications. [cite web | title = Headache Triggers: Caffeine | publisher = WebMD | month = June | year = 2004 | url = http://www.webmd.com/content/article/46/1826_50681.htm | accessdate = 2006-08-14 ] For this reason, many over-the-counter headache drugs include caffeine in their formula.
Coffee intake may reduce one's risk of
diabetes mellitustype 2 by up to half. While this was originally noticed in patients who consumed high amounts (7 cups a day), the relationship was later shown to be linear. [Salazar-Martinez E, Willet WC, Ascherio A, Manson JE, Leitzmann MF, Stampfer MJ, Hu FB. Coffee consumption and risk for type 2 diabetes mellitus. "Ann Intern Med" 2004;140:1-8. PMID 14706966.]
Coffee can also reduce the incidence of
cirrhosisof the liver[cite journal |author=Klatsky AL, Morton C, Udaltsova N, Friedman GD |title=Coffee, cirrhosis, and transaminase enzymes |journal=Arch. Intern. Med. |volume=166 |issue=11 |pages=1190–5 |year=2006 |pmid=16772246 |doi=10.1001/archinte.166.11.1190] and has been linked to a reduced risk of hepatocellular carcinoma, a primary liver cancer that usually arises in patients with preexisting cirrhosis. [Inoue M, Yoshimi I, Sobue T, Tsugane S; JPHC Study Group. Influence of coffee drinking on subsequent risk of hepatocellular carcinoma: a prospective study in Japan. "J Natl Cancer Inst" 2005;97:293-300. PMID 15713964.] The exact mechanism and the amount of coffee needed to achieve a beneficial effect are as yet unclear. [cite journal |author=Cadden IS, Partovi N, Yoshida EM |title=Review article: possible beneficial effects of coffee on liver disease and function |journal=Aliment. Pharmacol. Ther. |volume=26 |issue=1 |pages=1–8 |year=2007 |pmid=17555416 |doi=10.1111/j.1365-2036.2007.03319.x]
Coffee consumption is also correlated to a reduced risk of oral, esophageal, and pharyngeal cancer. [cite journal |last=Rodriguez |first=T |authorlink= |coauthors=Rodriguez T, Altieri A, Chatenoud L, Gallus S, Bosetti C, Negri E, Franceschi S, Levi F, Talamini R, La Vecchia C. |year=2004 |month=2 |title=Risk factors for oral and pharyngeal cancer in young adults |journal=Oral Oncol. |volume=40 |issue=2 |pages=207–13 |pmid=14693246 |doi=10.1016/j.oraloncology.2003.08.014] [cite journal |last=Tavani |first=A |authorlink= |coauthors=Bertuzzi M, Talamini R, Gallus S, Parpinel M, Franceschi S, Levi F, La Vecchia C. |year=2003 |month=10 |title=Coffee and tea intake and risk of oral, pharyngeal and esophageal cancer |journal=Oral Oncol. |volume=39 |issue=7 |pages=695–700 |pmid=12907209 |doi=10.1016/S1368-8375(03)00081-2] In
ovarian cancer, no benefit was found. [cite journal |author=Song YJ, Kristal AR, Wicklund KG, Cushing-Haugen KL, Rossing MA |title=Coffee, tea, colas, and risk of epithelial ovarian cancer |journal=Cancer Epidemiol. Biomarkers Prev. |volume=17 |issue=3 |pages=712–6 |year=2008 |pmid=18349292 |doi=10.1158/1055-9965.EPI-07-2511] In the Nurses Health Study, a modest reduction in breast cancerwas observed in postmenopausal women only, which was not confirmed in decaffeinated coffee. [cite journal |author=Ganmaa D, Willett WC, Li TY, "et al" |title=Coffee, tea, caffeine and risk of breast cancer: a 22-year follow-up |journal=Int. J. Cancer |volume=122 |issue=9 |pages=2071–6 |year=2008 |pmid=18183588 |doi=10.1002/ijc.23336]
Coffee reduces the incidence of
heart disease, though whether this is simply because it rids the blood of excess lipids or because of its stimulant effect is unknown. Fact|date=February 2007
Coffee is also a powerful stimulant for
peristalsisand is sometimes considered to prevent constipation. However, coffee can also cause excessively loose bowel movements. The stimulative effect of coffee consumption on the colon is found in both caffeinated and decaffeinated coffee. [cite journal |author=Brown SR, Cann PA, Read NW |title=Effect of coffee on distal colon function |journal=Gut |volume=31 |issue=4 |pages=450–3 |year=1990 |month=April |pmid=2338272 |pmc=1378422 |doi= |url=http://gut.bmj.com/cgi/reprint/31/4/450 | format=PDF] [cite journal |author=Rao SS, Welcher K, Zimmerman B, Stumbo P |title=Is coffee a colonic stimulant? |journal=Eur J Gastroenterol Hepatol |volume=10 |issue=2 |pages=113–8 |year=1998 |month=February |pmid=9581985]
alternative medicineoften recommend coffee enemas for "cleansing of the colon" due to its stimulus of peristalsis, although mainstream medicine has not proved any benefits of the practice.
Caffeine, together with related methylxanthine compounds, is a
diuretic. This seems to be mediated by the adenosine receptor. [cite journal |author=Rieg T, Steigele H, Schnermann J, Richter K, Osswald H, Vallon V |title=Requirement of intact adenosine A1 receptors for the diuretic and natriuretic action of the methylxanthines theophylline and caffeine |journal=J. Pharmacol. Exp. Ther. |volume=313 |issue=1 |pages=403–9 |year=2005 |month=April |pmid=15590766 |doi=10.1124/jpet.104.080432 |url=http://jpet.aspetjournals.org/cgi/content/full/313/1/403] The effects on actual hydration, though, are small. [cite journal |author=Grandjean AC, Reimers KJ, Bannick KE, Haven MC |title=The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration |journal=J Am Coll Nutr |volume=19 |issue=5 |pages=591–600 |year=2000 |month=October |pmid=11022872 |doi= |url=http://www.jacn.org/cgi/content/full/19/5/591]
Coffee contains the anticancer compound methylpyridinium. This compound is not present in significant amounts in other food materials. Methylpyridinium is not present in raw coffee beans but is formed during the roasting process from
trigonelline, which is common in raw coffee beans. It is present in both caffeinated and decaffeinated coffee, and even in instant coffee. [cite web
title=COFFEE CAN PREVENT COLON CANCER|
The Naked Scientists
Prevention of dental caries
tannins in coffee may reduce the cariogenic potential of foods. In vitro experiments have shown that these polyphenolic compounds may interfere with glucosyltransferase activity of mutans streptococci, which may reduce plaque formation. In rat experiments, tea polyphenolsreduced caries. [Touger-Decker, R. & van Loveren, C., Sugars and dental caries, "American Journal of Clinical Nutrition", October 2003, 78:4, 881S-892S.]
Coffee consumption decreased risk of
goutin men over age 40. In a large study of over 45,000 men over a 12-year period, the risk for developing gout in men over 40 was inversely proportional with the amount of coffee consumed. [cite journal |last=Choi |first=HK |authorlink= |coauthors=Willett W, Curhan G |year=2007 |month= |title=Coffee consumption and risk of incident gout in men: A prospective study |journal=Arthritis Rheum |volume=56 |issue=6 |pages=2049–55 |id= |url=http://www3.interscience.wiley.com/cgi-bin/abstract/114269884 |accessdate= |quote=|doi=10.1002/art.22712 ]
Many notable effects of coffee are related to its caffeine content. Amongst other known negative health associations it is not clear whether these are due to the caffeine or other unidentified compounds (suggesting that these may be modified by switching to decaffeinated coffee).
Coffee can damage the lining of the gastrointestinal organs, causing gastritis and ulcers. It is recommended for people with gatritis, colitis, and ulcers to stop consuming coffee. [cite web
Anxiety and sleep changes
Many coffee drinkers are familiar with "coffee jitters", a nervous condition that occurs when one has had too much caffeine. It can also cause
anxietyand irritability, in some with excessive coffee consumption, and some as a withdrawal symptom. Coffee can also cause insomniain some, while paradoxically it helps some sleep more soundly.Fact|date=February 2007
Like tea, coffee causes staining of the teeth. [Watts A. & Addy M., Tooth discolouration and staining: a review of the literature, "British Dental Journal", March 24 2001, 190:6 309-316 [http://www.nature.com/bdj/journal/v190/n6/full/4800959a.html] Accessed Nov 30, 2006]
2007study by the Baylor College of Medicine indicates that the diterpene molecules cafestoland kahweol, found only in coffee beans, putatively raise levels of low-density lipoproteinor LDL in humans.cite journal |author=Ricketts ML, Boekschoten MV, Kreeft AJ, Hooiveld GJ, Moen CJ, Müller M, Frants RR, Kasanmoentalib S, Post SM, Princen HM, Porter JG, Katan MB, Hofker MH, Moore DD. |title=The cholesterol-raising factor from coffee beans, cafestol, as an agonist ligand for the farnesoid and pregnane X receptors |journal=Molecular Endocrinology |volume=21 |issue=7 |pages=1603-16 |year=2007 |pmid = 17456796] This increase in LDL levels is an indicator that coffee raises cholesterol. The Baylor study serves to link cafestol and kahweol with higher levels of cholesterol in the body.
Paper coffee filters have a property that binds to lipid-like compounds which allows it to remove most of the cafestol and kahweol found in coffee. Brew methods which do not use a paper filter such as the use of a press pot, fail to remove any cafestol and kahweol from the final brewed product. In contrast, drip brewing with a paper filter removes most of the cafestol and kahweol from the coffee.
Caffeine has previously been implicated in increasing the risk of high blood pressure; however, recent studies have not confirmed any association. In a 12-year study of 155,000 female nurses, large amounts of coffee did not induce a "risky rise in blood pressure". [William Cromie, "Coffee Gets Cleared of Blood Pressure Risk", "Harvard Gazette". November 10 2005 (accessed August 1 2006 at http://www.news.harvard.edu/gazette/2005/11.10/06-coffee.html)] . Previous studies had already shown statistically insignificant associations between coffee drinking and clinical hypertension. Effect of coffee on morbidity and mortality due to its effect on blood pressure is too weak, and has not been studied. Other positive and negative effects of coffee on health would be difficult confounding factors.
Effects on pregnancy and menopause
A February 2003 Danish study of 18,478 women linked heavy coffee consumption during pregnancy to significantly increased risk of
stillbirths (but no significantly increased risk of infant death in the first year). "The results seem to indicate a threshold effect around four to seven cups per day," the study reported. Those who drank eight or more cups a day (64 U.S. fl oz or 1.89 L) were at 220% increased risk compared with nondrinkers. This study has not yet been repeated, but has caused some doctors to caution against excessive coffee consumption during pregnancy. [Wisborg K, Kesmodel U, Bech BH, Hedegaard M, Henriksen TB. Maternal consumption of coffee during pregnancy and stillbirth and infant death in first year of life: prospective study. "BMJ" 2003;326:420. PMID 12595379.]
There are also gender-specific effects: in some
PMSsufferers it increases the symptoms; it can reduce fertilityin women; it may increase the risk of osteoporosisin postmenopausal women.
Decaffeinated coffee is also regarded as a potential health risk to pregnant women due to the high incidence of chemical solvents used to extract the caffeine. The impact of these chemicals is debated, however, as the solvents in question evaporate at 80–90 °C, and coffee beans are decaffeinated before roasting, which occurs at approximately 200 °C. As such, these chemicals, namely trichloroethane and
methylene chloride, are present in trace amounts at most, and may not pose a significant threat to embryos and fetuses.
Coronary artery disease
A 2004 study tried to discover why the beneficial and detrimental effects of coffee conflict. The study concluded that consumption of coffee is associated with significant elevations in biochemical markers of
inflammation. This is a detrimental effect of coffee on the cardiovascular system, which may explain why coffee has so far only been shown to help the heart at levels of four cups (24 fl oz or 600 mL) or fewer per day. [Zampelas A, Panagiotakos DB, Pitsavos C, Chrysohoou C, Stefanadis C. Associations between coffee consumption and inflammatory markers in healthy persons: the ATTICA study. "Am J Clin Nutr" 2004;80:862-7. PMID 15447891.]
The health risks of decaffeinated coffee have been studied, with varying results. One variable is the type of decaffeination process used; while some involve the use of
organic solvents which may leave residual traces, others rely on steam.Fact|date=February 2007
A study has shown that
cafestol, a substance which is present in boiled coffee drinks, dramatically increases cholesterollevels, especially in women. Filtered coffee contains only trace amounts of cafestol.
Polymorphisms in the "
CYP1A2" gene may lead to a slower metabolism of caffeine. In patients with a slow version of the enzyme the risk for myocardial infarction(heart attack) is increased by a third (2-3 cups) to two thirds (>4 cups). The risk was more marked in people under the age of 59. [Cornelis MC, El-Sohemy A, Kabagambe EK, Campos H. Coffee, CYP1A2 genotype, and risk of myocardial infarction.JAMA. 2006 Mar 8;295(10):1135-41. PMID 16522833.]
A Harvard study over 20 years of 128,000 people published in 2006 concluded that there was no evidence to support the claim that coffee consumption itself increases the risk of
coronary heart disease. The study did, however, show a correlation between heavy consumption of coffee and higher degrees of exposure to other coronary heart disease risk factors such as smoking, greater alcohol consumption, and lack of physical exercise. [Lopez-Garcia E, van Dam RM, Willett WC, Rimm EB, Manson JE, Stampfer MJ, Rexrode KM, Hu FB. Coffee consumption and coronary heart disease in men and women: a prospective cohort study. "Circulation" 2006;113:2045-53. PMID 16636169.] The results apply only to coffee filtered through paper filters, which excludes boiled coffee and espresso, for example. Additionally, the lead researcher on this study acknowledged that subsets of the larger group may be at risk for heart attack when drinking multiple cups of coffee a day due to genetic differences in metabolizing caffeine.Fact|date=February 2007
The Iowa Women's Health Study showed that women who consumed coffee actually had fewer cardiovascular disease incidents and lower cancer rates than the general population. For women who drank 6 or more cups, the benefit was even greater. However, this study excluded 35% of its original participants who already had cardiovascular disease and other chronic diseases when the study began. Since participants were all over the age of 55, no good conclusion can be drawn about the long term effect of coffee drinking on heart disease from this study. [Andersen LF, Jacobs DR Jr, Carlsen MH, Blomhoff R. Consumption of coffee is associated with reduced risk of death attributed to inflammatory and cardiovascular diseases in the Iowa Women's Health Study. "Am J Clin Nutr" 2006;83:1039-46. PMID 16685044.]
Potential effects of tea on health
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