Coffee consumption has been shown to have minimal or no impact, positive or negative, on cancer development; however, researchers involved in an ongoing 22-year study by the Harvard School of Public Health state that “the overall balance of risks and benefits [of coffee consumption] are on the side of benefits. For example, men who drank six or more cups of coffee per day were found to have a 20% reduction in developing prostate cancer. Other studies suggest coffee consumption reduces the risk of being affected by Alzheimer’s disease, Parkinson’s disease, heart disease, diabetes mellitus type 2, cirrhosis of the liver, and gout. A longitudinal study in 2009 showed that those who consumed a moderate amount of coffee or tea (3–5 cups per day) at midlife were less likely to develop dementia and Alzheimer’s disease in late-life compared with those who drank little coffee or avoided it altogether. It increases the risk of acid reflux and associated diseases. Most of coffee’s beneficial effects against type 2 diabetes are not due to its caffeine content, as the positive effects of consumption are greater in those who drink decaffeinated coffee. The presence of antioxidants in coffee has been shown to prevent free radicals from causing cell damage. A recent study showed that roast coffee, high in lipophilic antioxidants and chlorogenic acid lactones, protected primary neuronal cell cultures against hydrogen peroxide-induced cell death.
American scientist Yaser Dorri has suggested that the smell of coffee can restore appetite and refresh olfactory receptors. He suggests that people can regain their appetite after cooking by smelling coffee beans, and that this method can also be used for research animals.
Over 1,000 chemicals have been reported in roasted coffee; more than half of those tested (19/28) are rodent carcinogens at maximum tolerated dose. Coffee’s negative health effects are often blamed on its caffeine content. Instant coffee has a much greater amount of acrylamide than brewed coffee. Research suggests that drinking caffeinated coffee can cause a temporary increase in the stiffening of arterial walls. Caffeinated coffee is not recommended for everybody. It may aggravate preexisting conditions such as gastroesophageal reflux disease, migraines, arrhythmias, and cause sleep disturbances.
Coffee is no longer thought to be a risk factor for coronary heart disease. One study suggests that it may have a mixed effect on short-term memory, by improving it when the information to be recalled is related to the current train of thought but making it more difficult to recall unrelated information. Caffeine has been associated with its ability to act as an antidepressant. A review by de Paulis and Martin indicated a link between a decrease in suicide rates and coffee consumption, and suggested that the action of caffeine in blocking the inhibitory effects of adenosine on dopamine nerves in the brain reduced feelings of depression. A 1992 study concluded that about 10% of people with a moderate daily intake (235 mg per day) experienced increased depression and anxiety when caffeine was withdrawn, but a 2002 review of the literature criticised its methodology and concluded that the effects of caffeine withdrawal are still controversial. About 15% of the U.S. general population report having stopped drinking coffee altogether, citing concern about health and unpleasant side effects of caffeine.
Source and References http://en.wikipedia.org/wiki/Coffee