Coffee is a very interesting product. Being one of the most popular drinks in the world, it is a subject of many studies where researchers try to find out how it affects poeple's health.
For a long time coffee was not considered a healthy drink. It has a history of being blamed for many ills. But some recent studies indicate that coffee may not be so bad after all. So which is it – good or bad for the health?
I like coffee a lot, and to find an answer to that question for myself, I did my own research and noted the most significant benefits and potential serious health risks of coffee drinking. Here is what I have found:
Researchers found that a typical serving of coffee contains more antioxidants than typical servings of grape juice, blueberries, raspberries and oranges.
Study conducted in Switzerland showed that coffee contains the most amount of polyphenols in comparison to green teas, herbal tea, and cocoa. According to this study, a cup of coffee has up to four times more polyphenols than a cup of green tea.
Coffee is potentially protective against the development of type 2 diabetes. US Nurses Health Study found that moderate drinking of coffee may lower the risk of type 2 diabetes in younger and middle aged women. The finding that higher consumption of decaffeinated coffee was also associated with a redused risk of diabetes suggests that the protective effect could not be attributed exclusively to caffeine, but rather should be explained by various antioxidants, most probably chlorogenic acid.
Prospective study based on an oral glucose test confirmed striking protective effect of caffeinated coffee against incident type 2 diabetes (in both with impaired glucose and those with normal).
The time of the day when you drink coffee is also important. According to a recent research, coffee at lunchtime has the most protecting effects than in any other time of the day.
3 Parkinson’s disease
There is strong evidence that regular coffee consumption reduces the risk of Parkinson’s disease. A number of studies[11-13] have demonstrated that people who drink coffee on a regular basis are significantly less likely to develop Parkinson’s.
4 Liver damage
Coffee drinking may protect against liver cirrhosis, especially alcoholic cirrhosis. A study found a 22% reduced risk of developing alcoholic cirrhosis for each cup of coffee drunk per day.
Drinking three or more cups of coffee daily also lessens the risk of progression of chronic hepatitis C.
There is some evidence that coffee drinking may be protective against gallstone formation in men and women[15-16]. The study shows that regular coffee drinkers (four or more cups a day) have 25 percent less chance of developing gallstones compared to those who drink none.
6 Kidney stones
Hyperuricemia (high level of uric acid in the blood) can contribute to both gout and kidney stone formation. Drinking one to three cups of coffee a day lowers gout risk by only 8%, whereas four or five cups a day may decrease the serum uric acid level and the risk of gout in men by 40%.
8 Work performance
Caffeine is a well-known stimulant. Many studies[20-22] demonstrate the beneficial effects of coffee on alertness, attentiveness, and wakefulness. The cup of coffee can increase information processing.
There is some evidence that coffee may help manage asthma and even control attacks when medication is unavailable. Caffeine in coffee is related to theophylline, an old asthma medication. It can improve airways function modestly, for up to four hours, and improve asthma symptoms.
10 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 at midlife were significantly less likely to develop Alzheimer’s disease later in life. The recent research in mice proves that drinking five cups of coffee a day could even reverse memory problems seen in Alzheimer's disease.
These were benefits of coffee drinking. Now let’s look at the potential health risks associated with coffee. Coffee, mainly in large doses, can cause several problems for susceptible persons. However, despite several detrimental health effects, people who drink coffee regularly are not at increased risk of mortality.
1 Heart disease
The relation between coffee and risk of cardiovascular disease has been examined in many studies, but the results remain controversial. Most studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk[23-24]. The strongest evidence for the suggestion that coffee is associated with increased risk of coronary heart disease comes from the case control studies.
Coffee is a complex mixture of compounds that may have either beneficial or harmful effects on the cardiovascular system. On one hand, diterpenes cafestol and kahweol present in unfiltered coffee and caffeine each appear to increase risk of coronary heart disease. High quality studies (randomized controlled trials)[26-27] have confirmed the cholesterol-raising effect of diterpenes, which may contribute to the risk of coronary heart disease. On the other hand, a lower risk of heart disease among moderate coffee drinkers might be due to antioxidants found in coffee.
Besides that, coffee consumption is also associated with an increase of plasma homocysteine, a risk factor for coronary heart disease[28-29].
To get an idea of where the confusion comes from, consider two recent studies. A study of 128,000 men and women showed no increase in the risk of heart disease from drinking filtered coffee. The findings of the study – published in May 2006 in the journal Circulation – indicated that it didn’t matter how much coffee participants drank. Another study of 4,000 coffee drinkers published in March 2006 in the Journal of the American Medical Association found that two or more cups of coffee a day can increase the risk of heart disease in people with a specific – and fairly common – genetic mutation that slows the breakdown of caffeine in the body. The design of a study can have some effect on the interpretation of results, which may be another reason for the different conclusions. Overall, given the research reviewed it would be reasonable to conclude that coffee poses little or no threat to healthy adults.
Interestingly, the researchers did find that people who drank more coffee were more likely to be smokers, drink more alcohol, drink less tea, take vitamin supplements, or exercise regularly, all of which have been linked to increased risks of heart problems.
2 Increased cholesterol levels
Heavy consumption of boiled coffee elevates blood total and LDL cholesterol levels. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes responsible for cholesterol-raising effects of coffee[26-27]. Diterpenes are extracted by hot water but are retained by a paper filter. This explains why filtered coffee does not affect cholesterol, whereas Scandinavian boiled, cafetiere, and Turkish coffees do.
5 Blood pressure
Although coffee consumption is not a significant risk factor for hypertension, it produces unfavourable effects on blood pressure[34-35]. No doubt caffeine is responsible for blood pressure increase. People prone to hypertension may be more susceptible to coffee blood pressure elevating effects. But even in people who don't have high blood pressure, caffeine can cause a short, but significant increase in blood pressure.
Recent Italian study found that coffee drinking can slightly increase the risk for development of sustained hypertension in persons with elevated blood pressure.
6 Osteoporosis (bone loss)
Coffee can impair absorption of calcium from the digestive tract and may induce an extra urinary excretion of calcium. Heavy coffee drinking (4 cups=600 ml or more) can modestly increase the risk of osteoporosis, especially in women with a low calcium intake[37-38]
7 Disrupted sleep
Excess caffeine can overstimulate the central nervous system. High amounts of caffeine produce negative effect on sleep onset and quality. However, there are large individual differences in the effects of caffeine on sleep. Many people consume coffee during the evening and have no problems falling asleep. Some people find that the mild stimulation of caffeine consumed shortly before a bed time delays the time to fall asleep.
Some people suffer from heartburn after drinking coffee. Coffee promotes gastro-oesophageal reflux, but is not associated with dyspepsia.
The caffeine in coffee is a mild diuretic and can increase the volume of urine excreted. However, this effect can be easily counteracted by the drinking extra glass of water.
10 Rheumatoid arthritis
Decaffeinated coffee may increase the risk of rheumatoid arthritis. Researchers speculate that rather than the presence or absence of caffeine being the culprit, there may be something in the way decaffeinated coffee is processed that triggers an arthritic response, perhaps industrial solvents.
Interestingly, the study linking decaffeinated coffee and rheumatoid arthritis suggests that, “Women who drink more than three cups of tea a day are much less likely to develop the disease than those who don’t drink tea”.
Another study found that people who drank four or more cups of coffee a day had twice the risk of developing rheumatoid arthritis, compared with those who drank less coffee.
Dr. Maarku Heliovaara of the National Public Health Institute in Helsinki and colleagues looked at data from nearly 19,000 healthy men and women who entered a study in the early 1970s and were followed for 15 years. Coffee drinkers were at higher risk of developing rheumatoid factor-associated rheumatoid arthritis.
It is not clear why coffee might be associated with rheumatoid factor. Most people in the study drank boiled coffee, a practice no longer common in Finland. It is possible that some ingredient in coffee that is associated with rheumatoid factor is removed by the filtration, according to the researchers.
Coffee & Pregnancy
We have an article that describes the findings of latest studies on the subject of effects of coffee during pregnancy. Despite the fact that it is extensively researched, the results remain contradictory.
The key is quantity and quality. For those consuming moderate amounts of coffee (3-4 cups/day providing 300-400 mg/d of caffeine), there is little evidence of health risks and some evidence of health benefits. However, some people, including persons with hypertension, osteoporosis, heart disease, pregnant women, children, adolescents, and elderly may be more vulnerable to the adverse effects of coffee.
At least, coffee is far less toxic and more healthier than the sugar-laden drinks like soda.
What’s your conclusion? Does the benefit outweigh the negative effects?
Sources & References
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