Potential Benefits of Coffee for Health and Life Expectancy
A Healthy Beverage With Some Drawbacks
Coffee has had a reputation as a delicious but not-very-healthy beverage for a long time. Recently though—to the joy of coffee lovers everywhere that the news has reached—researchers have found that it may have some important health benefits. According to the investigators, drinking coffee significantly reduces the risk of several serious diseases that are more likely to strike us as we grow older, including type 2 diabetes, Parkinson's disease, prostate cancer, liver disease, liver cancer, one type of skin cancer, and Alzheimer's disease.
Experiencing fewer diseases, especially those that may be fatal, can do wonders for increasing our lifespan. It certainly seems that we would have a chance of living longer if we drank coffee regularly, but it would be nice to have evidence for this assumption. Interestingly, there is some evidence for increased lifespan in coffee drinkers.
In May, 2012, The New England Journal of Medicine published the results of an almost fourteen year study of over 400,000 people. People who drank coffee every day were significantly less likely to die than non-coffee drinkers. In 2017, Spanish scientists reported that people who drank at least four cups of coffee a day had a 64% reduced risk of dying compared to the people in their survey who drank no or very little coffee. This study involved around 20,000 people and lasted for ten years. Drinking coffee has some drawbacks, but according to the present state of our knowledge its potential benefits may far outweigh its disadvantages.
Results of surveys are often considered to be less accurate than results obtained from clinical trials. Surveys that involve a large number of people are generally given some respect, though.
Coffee Drinking and Longevity
The survey of coffee drinkers published in The New England Journal of Medicine asked 400,000+ people to fill in a questionnaire at the start of the study. In this questionnaire, people aged 50 to 71 described their coffee drinking habits. Those who had a serious illness were excluded from the study, and the data from those who smoked was eliminated. After about 13.6 years, the people were surveyed again to see if they were still alive.
In general, the survey showed that the greater the number of cups of coffee drunk in one day, the lower the chance of dying. This trend held true up to and including four or five cups of coffee a day. At six cups a day the benefit was still present but had decreased slightly. The maximum decrease in death risk was 16% for women and 12% for men. The results were unaffected by whether the coffee was caffeinated or decaffeinated.
There have been criticisms of the study. First, as in any survey-type study, we can't prove that in every case coffee drinking kept someone alive. People may have lived longer because they had a healthier lifestyle than other people in the study or because they had genes that gave them longevity, for example. Another criticism is that people were asked about their coffee drinking habits only at the start of the survey. People's choice of beverage can change over a thirteen to fourteen year period. The large number of people involved in the survey helps to reduce the possible sources of error, however. The table below summarizes the results.
Coffee Consumption and Decrease in Death Risk
Cups of Coffee Drunk Per Day
Decrease in Death Risk in Females
Decrease in Death Risk in Males
two to three
four to five
six or more
The SUN Project
The study described at the European Society of Cardiology Congress in 2017 was also based on a survey and subject to the disadvantages of this type of research. It's interesting that like the 2012 study it supports the idea of increased lifespan due to coffee consumption, however. The study was part of the SUN project (Seguimiento Universidad de Navarra). The subjects were graduates from a Spanish university.
A 64% lower risk of all-cause mortality when at least four cups of coffee were drunk each day is much higher than the value obtained in the 2012 study. The researchers found that the benefits of drinking coffee were strongest for people who were at least forty-five years old. They say that their study was the first one done with people in a Mediterranean country. It's probably going to take some time to figure out the interactions between coffee drinking, typical diet and exercise habits in an area, environmental factors, and genetics. It certainly seems that coffee is beneficial with respect to lifespan, however.
Possible Reasons for Life Extension
There are two possible explanations for why coffee (apparently) reduces death risk. The beneficial effect could be due to coffee's ability to lower the risk of specific diseases and/or it could be due to helpful substances in the roasted coffee beans. The beans are believed to contain a thousand or more different chemicals, including antioxidants and antibacterial substances. One coffee antioxidant of special interest to researchers in relation to human health is chlorogenic acid, a member of the polyphenol family. Antioxidants fight potentially dangerous free radicals that are made in the body as chemical reactions occur.
The discoveries showing that coffee drinking reduces the risk of certain diseases are exciting. Some of the diseases are listed below. It should be noted that the statistics were obtained from surveys rather than clinical trials. While survey results are important, they don't provide definite proof that a substance has a health benefit.
- Drinking four to five cups of caffeinated coffee every day in midlife has been shown to protect against Alzheimer's disease in old age. Starting to drink coffee at an older age has some protective benefit as well.
- In mice, researchers have shown that caffeinated coffee reduces the buildup of beta-amyloid in the brain. This substance makes up the characteristic plaque seen in the brains of human Alzheimer's patients. Drinking other caffeinated beverages doesn't have the same benefit.
- Researchers at the Harvard School of Public Health analyzed data from the Nurses' Health Study ll (47,510 women), the Health Professionals Follow-Up Study (27,759 men), and the Brigham and Women's Hospital-Based Nurses' Health Study (48,464 women). They found that people who increased their consumption of caffeinated coffee by more than one cup a day over a four-year period had an 11% lower risk of developing type 2 diabetes in the following four years than those who made no change to their consumption.
- In the study described above, people who lowered their consumption of caffeinated coffee by more than one cup a day had a 17% higher risk of type 2 diabetes.
- Drinking two to three cups of caffeinated coffee a day seems to reduce the risk of Parkinson's disease by about 25%, according to an analysis of different research studies.
- A small study has shown that the caffeine equivalent of three cups of coffee a day improves movement problems in people with Parkinson's disease.
Cancer Risk and Cardiovascular Problems
Coffee may reduce the risk of some types of cancer. The beverage seems to be both beneficial and detrimental with respect to cardiovascular problems.
- According to a twelve year study of more than 47,000 men in the United States, the men who drank six or more cups of coffee a day had a 20% lower risk of developing prostate cancer and a 60% lower risk of developing the most dangerous form of prostate cancer. Drinking one to three cups of coffee a day resulted in a 30% lower risk of the most dangerous form of prostate cancer. The results of the study were unaffected by the amount of caffeine in the coffee.
- Some surveys suggest that drinking coffee significantly reduces the rate of liver disease or liver cancer. A recent study discovered that the rate of hepatocellular cancer decreased as the number of extra cups of caffeinated coffee per day increased (up to five extra cups of the beverage a day). Decaffeinated coffee was also effective, but to a lesser extent.
- A survey of 113,000 nurses and health professionals found that women who drank more than three cups of caffeinated coffee a day had a 21% lower chance of developing basal cell carcinoma, one form of skin cancer. Men had a 10% risk reduction. Consumption of an equivalent amount of caffeine from other foods or drinks had a similar benefit.
- Some research suggests that coffee reduces the risk of heart attacks and strokes in the long term, but a few studies show that immediately after drinking the beverage the risk of a heart attack or stroke temporarily increases.
Different types of coffee may have different effects on health. This is a topic that needs to be investigated in more detail.
A Coffee Poll
How often do you drink coffee?
Some Disadvantages of Drinking Coffee
There are disadvantages to drinking coffee. Some—but not all of them—can be avoided.
- Coffee stains teeth. These stains can be reduced by rinsing the mouth out with water immediately after drinking the beverage, however. A dental hygienist can also remove the stains.
- Unfiltered coffee contains two chemicals—cafestol and kahweol—which raise the level of LDL cholesterol in our blood. This is the type of cholesterol that can cause the buildup of fatty deposits in the lining of the arteries and increase the risk of a heart attack or stroke. Most coffee is filtered, however, which removes the chemicals. Espresso does contain cafestol and kahweol, but it's drunk in smaller quantities than other types of coffee.
- In some people caffeine has a diuretic effect, increasing the person's need to urinate.
- Coffee can relax muscles in the digestive tract and cause defecation and even diarrhea. In addition, it may cause acid reflux.
- Caffeinated coffee may have a very energizing effect and produce "jitters" in sensitive people. It may also trigger heart palpitations.
- Coffee has a dual effect on headaches. It has been found to make some pain relievers more effective, which can help a headache. On the other hand, drinking coffee can give some people a headache.
It's important to remember that discussions about coffee's potential health benefits are concerned with the beverage on its own and not with ingredients that may be added to it. These can make a big difference to any beneficial effects of the drink. Drinking several cups of coffee a day that contain added fat and sugar isn't healthy.
The Possible Role of Genetic Differences
If you already drink coffee, it's good to know that it most likely has important health benefits. Should you start drinking coffee if you don't already do so, or should you increase your consumption of the beverage? Scientists are reluctant to recommend this action, especially since there may be major drawbacks for some people.
In recent years, some scientists have suggested that our genetic makeup may affect our body's response to coffee and caffeine. Since we don't know what genes we possess, the best that we can do when deciding whether we should drink coffee is to observe our symptoms. For some people, the drawbacks of drinking the beverage may be too unpleasant. Continuing reports of coffee's health benefits make coffee consumption very tempting if there are no or only minor drawbacks, however.
- Coffee and disease prevention from Harvard Health Publications
- Possible Health Effects of Caffeinated Coffee Consumption on Alzheimer’s Disease and Cardiovascular Disease from the Korean Society of Toxicology (Abstract)
- Caffeine and beta-amyloid in mice from the NIH (National Institutes of Health)
- Increasing daily coffee consumption may reduce type 2 diabetes risk from the Harvard School of Public Health
- Parkinson's disease and other health problems from the Harvard Gazette
- Liver cancer from the NIH
- Hepatocellular cancer from the University of Southampton
- Coffee and basal cell carcinoma from Scientific American
- Coffee may reduce risk of lethal prostate cancer from the Harvard School of Public Health
- Higher coffee consumption associated with lower risk of early death from the Medical Xpress news service
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
Questions & Answers
© 2012 Linda Crampton