Coffee contains caffeine, which acts as a stimulant. For this reason, it is often consumed in the morning and when feeling tired. Students preparing for examinations with late-night cram sessions frequently use coffee to stay awake. Many office workers take a coffee break when they have low energy.
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 cortisone and adrenaline, two stimulating hormones.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 remove the caffeine) or the use of a chemical solvent such 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 dioxide has also been employed
Decaffeinated coffee usually loses some flavor over normal coffee. 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.
BenefitsReduced risk of Alzheimer's disease and Dementia
Several studies comparing moderate coffee drinkers (defined as 3-5 cups per day) with light coffee drinkers (defined as 0-2 cups per day) found that those who drank more coffee were significantly less likely to develop Alzheimer's disease later in life.A longitudinal study in 2009 found that moderate coffee drinkers had reduced risk of developing dementia in addition to Alzheimer's disease .
Reduced risk of gallstone disease
Drinking caffeinated coffee has been correlated with a lower incidence of gallstones and gallbladder disease in both men and women in two studies performed by the Harvard School of Public Health. A lessened risk was not seen in those who drank decaffeinated coffee. A recent study showed that roast coffee protected primary neuronal cells against hydrogen peroxide-induced cell death.
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 disease later in life.Likewise, a second study found an inverse relationship between the amount of coffee regularly drunk and the likelihood of developing Parkinson's disease.
Cognitive performance
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.Another study found that women over the age of 80 performed significantly better on cognitive tests if they had regularly drunk coffee over their lifetimes.
Analgesic enhancement
Coffee contains caffeine, which increases the effectiveness of pain killers, especially migraine and headache medications.For this reason, many over-the-counter headache drugs include caffeine in their formula.
Antidiabetic
Coffee intake may reduce one's risk of diabetes mellitus type 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.
Liver protection
Coffee can also reduce the incidence of cirrhosis of the liver and has been linked to a reduced risk of hepatocellular carcinoma, a primary liver cancer that usually arises in patients with preexisting cirrhosis.The exact mechanism and the amount of coffee needed to achieve a beneficial effect have long been unclear.The cytokine transforming growth factor (TGF) beta has long been recognized for promoting fibrosis ability acting through the Smad family of transcription factors. In an interesting report recently published in the Journal of Hepatology, Gressner and colleagues provide the first mechanistic context for the epidemiological studies on coffee drinkers by showing that caffeine may have potent anti-fibrotic capabilities through its ability to antagonize the Smad pathway .
Cancer
Coffee consumption is also correlated to a reduced risk of oral, esophageal, and pharyngeal cancer.In ovarian cancer, no benefit was found.In the Nurses' Health Study, a modest reduction in breast cancer was observed in postmenopausal women only, which was not confirmed in decaffeinated coffee.According to one study, coffee protects the liver from cancer.Another preliminary study found a correlation between coffee consumption and a lower risk of aggressive prostate cancer.
Cardioprotective
According to the longitudial study led by Esther López García of Universidad Autónoma de Madrid, coffee reduces the incidence of dying from heart disease .
Laxative/diuretic
Coffee is also a powerful stimulant for peristalsis and 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.
Practitioners in alternative medicine often recommend coffee enemas for "cleansing of the colon" due to its stimulus of peristalsis, although medicine has not proved any benefits of the practice.
Contrary to popular belief, caffeine does not act as a diuretic when consumed in moderation, and does not lead to dehydration or to a water-electrolyte imbalance; current evidence suggests that caffeinated beverages contribute to the body's daily fluid requirements no differently from pure water.
Antioxidant
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.A recent study shows that roast coffee contains more lipophilic antioxidants and chlorogenic acid lactones and are more protective against hydrogen peroxide-induced cell death in primary neuronal cells than green coffee .
Prevention of dental caries
The 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.
Gout
Coffee consumption decreased risk of gout in 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.
Cancer
Over 1,000 chemicals have been reported in roasted coffee, and 19 are known rodent carcinogens;however, most substances cited as rodent carcinogens occur naturally and should not be assumed to be carcinogenic in humans at exposure levels typically experienced in day-to-day life.
Gastrointestinal problems
Coffee can damage the lining of the gastrointestinal organs, causing gastritis and ulcers. The consumption of coffee is therefore not recommended for people with gastritis, colitis, and ulcers.
