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Are Health Benefits of Coffee Hype or Real?
Coffee. The pungent, bittersweet aroma in the morning as it brews in your coffeepot. The feel of a warm mug in your hands, steam rising into a crisp fall morning. The buzz of a coffeeshop – a too-perky server behind the counter, lively conversations, and 30-somethings hunched over their laptops typing at breakneck speed.
Truck stop coffee. Grocery-store brand coffee. Specialty coffees. Organic fair-trade coffee.
As coffeehouses from Starbucks to local roasters have sprung up in cities large and small...
[Short break while I head down to the coffeeshop on the corner to pick up a cup. Locally roasted. Fresh brewed. Black.]
… researchers have begun to investigate coffee’s health effects. The resulting body of research, which is growing almost as fast as coffee consumption, suggests that coffee may, indeed, offer significant health benefits.
Once thought of as little more than a “vice,” coffee has taken on a new image. Once the domain of truck drivers, writers, and those working graveyard shifts, coffee has become the beverage of choice for many health conscious consumers. It hasn’t quite achieved the mythical health status of pomegranate or blueberry juice, nor does it have the elegant allure of a tea ritual. But coffee is no longer the bad guy in the cup.
Did You Know?
Here's a little coffee trivia:
- Worldwide, more than 400 billion cups of coffee are consumed each year, about two billion per day
- Americans drink more than 400 million cups of coffee every day, about 3.5 cups for every
- About 70 million cups of coffee are consumed daily in the U.K.
- Of Americans who drink coffee daily, 86 percent make it in their own homes
- The retail value of the U.S. coffee market topped $30 billion in 2010
- Nearly 60% of U.S. adults ages 18 years and older drink coffee daily or almost daily
- More than 125 million people are involved in coffee farming in some way. Most are in rural and developing regions.
- There are two primary types of coffee: Arabica and Robusta. Arabica type beans are generally makes to make specialty coffees
- The top coffee-importing countries – France, Germany, Italy, Japan, and the United States – imported about 37.3 million bags from January to September 2010, an increase of nearly 1 million from the previous year.
- The United States is the world’s largest single buyer and accounts for more than one fourth of unroasted global coffee imports. In 2008-2009, the United States imported 21.5 million bags of coffee.
- Annual per capita coffee consumption in Scandinavia is 26.4 pounds, higher than in any other region of the world
- In Turkey, a woman can legally divorce her husband if he does not provide her with her daily quota of coffee
Coffee’s bad rap stems partly from early studies, many of which found higher rates of heart attack and some cancers in people who drank coffee regularly. But when scientists began using more sophisticated epidemiological techniques to tease out the effects of coffee consumption from effects of other behaviors such as smoking, many studies seemed to show that that coffee actually has a protective effect.
Some of the most compelling evidence comes from a large prospective study reported in 2012, which suggests that coffee consumption may be associated with a reduced risk of death from all causes. For the study, a team of researchers who were mostly from the National Cancer Institute, asked more than 400,000 middle-aged volunteers about their coffee consumption. People who had cancer, heart disease, or stroke were excluded from the study when it began in 1995. By 2008, more than 50,000 study participants had died.
After controlling for factors such as cigarette smoking, the researchers calculated that men who drank two to three cups of coffee per day were 10 percent less likely to have died. Among women who drank a similar amount of coffee, the risk of dying was 13 percent less than for their non-coffee drinking counterparts. Although the study did not show that coffee caused the difference in mortality, the correlation is notable.
Researchers have been able to establish links – some stronger than others – between coffee consumption and reduced risk of chronic diseases including dementia, type 2 diabetes mellitus, Parkinson’s disease, and cancers including prostate, liver, and breast cancer. One study has shown that coffee may even help to mitigate the effects of smoking on the liver and reduce the risk of liver cancer in smokers.
While scientists don’t fully understand the mechanisms behind coffee’s potential effect on such a wide range of conditions, they do know that coffee contains phytochemicals – naturally occurring compounds produced by plants – that may affect health. Several of the phytochemicals found in coffee have anti-inflammatory and antioxidant effects. They may also help to control the way the body uses sugar.
So in case you needed another reason to brew up another cup of Joe, here are a few good ones:
Nice to Know
The phrase “cup of Joe” dates back to Admiral Josephus "Joe" Daniels, whose first action when he became Chief of Naval Operations was to outlaw alcohol on U.S. Navy ships. Coffee soon became the drink of choice on the ships -- thanks to Joe.
Dementia Prevention and Control
Coffee consumption has been linked to reduced risk of dementia, especially Alzheimer’s-type dementia. However, "linked to" still needs to be defined. There’s enough epidemiological evidence to say there’s a link of some sort. Whether that link is causal or not is another question. The evidence is still not firm enough for health experts to recommend coffee consumption as a tool for Alzheimer’s prevention, but as the evidence grows, it's still .
One of the most intriguing studies on the caffeine/dementia prevention link appeared in 2012. Researchers at the University of Illinois Urbana-Champaign, were able to show a direct correlation between memory formation and caffeine consumption. The research, which appeared in the Journal of Neuroscience, was conducted by a team led by Gregory Freund, a professor at the University of Illinois' College of Medicine.
Freund’s team withheld oxygen from the mice for a short time, which temporarily disrupted their ability to form memories. The team gave half of the mice a dose of caffeine equivalent to four cups of coffee. When they gave the mice oxygen again, the mice who had received the caffeine were able to form new memories 33 percent sooner than the “decaf” mice.
The researchers then examined the mice’s brain tissue. In all of the mice, they found that the lack of oxygen had caused levels of adenosine to increase beyond normal. Adenosine is a chemical found in all cells of the body. Cells usually use it to produce energy, but if it escapes the cell, it can cause cell destruction, leading to inflammation. In turn, inflammation interferes with neurons’ (nerve cells’) function and may contribute to degeneration of the neurons – the physiological changes seen in dementia. In the mice that had received caffeine, adenosine’s action had been disrupted.
Having trouble concentrating here. Maybe it's time for another cup.
Type 2 Diabetes
Research into a potential link between coffee consumption and a reduced risk of type 2 diabetes mellitus (“sugar diabetes”) has been going on for more than a decade, but the verdict is still out on whether coffee should be added to the list of possible diabetes prevention tools.
One of the earliest large studies to investigate a potential association between coffee consumption and risk of type 2 diabetes was reported in 2002. Investigators queried 17,111 Dutch men and women aged 30-60 years about their coffee-drinking habits and then tracked whether they developed diabetes over about seven years. People in the study who drank at least seven cups of coffee a day were half as likely to develop diabetes as those who drank two cups or fewer a day.
In 2004, a U.S.-based research team published results of an even larger investigation of coffee drinking and diabetes prevention involving nearly 42,000 men and more than 82,000 women in the United States. Their research, which appeared in the Annals of Internal Medicine, included decaffeinated coffee as a study variable.
Women in the study who regularly drank six or more cups of coffee daily lowered their risk of developing type 2 diabetes by about 30 percent. Men who drank more than six cups of caffeinated coffee each day had a 50 percent lower chance of developing the disease compared to non-coffee drinkers. The authors suggested that the protective effects could be partly due to caffeine, but the antioxidants and magnesium contained in coffee could also play a role. Participants who drank decaffeinated coffee also lowered their risk, but not as much .
A host of similar studies followed suit, yet many studies suffered from poor design, small study bias, and reliance on self-reporting. In 2009, an Australian research team published results of a review and meta-analysis of 18 previous studies that had explored the association between coffee consumption and diabetes, involving a total of 457,922 participants.
For every additional cup of coffee consumed per day, the risk of diabetes decreased by 7 percent in comparison to non-coffee drinkers. However, they cautioned, because of small-study bias, their results could overestimate the true strength of the association. They also found associations between decaffeinated coffee and reduced risk of diabetes. They concluded that “The putative protective effects of these beverages warrant further investigation in randomized trials.”
Several studies have suggested that caffeine consumption may reduce the risk of developing several types of cancer, including basal-cell carcinoma, glioma (a cancer of the brain and central nervous system), and ovarian cancer.
While scientists aren’t sure exactly how cancer might protect us from cancers, some of the naturally occurring compounds they are investigating include:
- Caffeine. Although most well known for its stimulant properties, caffeine also inhibits cell growth and encourages programmed cell death (apoptosis). These abilities may underlie caffeine’s role in preventing cancer and slowing tumor growth.
- Diterpenes cafestol and kahweol, which may inhibit cancer growth.
- Chlorogenic acid, which, along with caffeic acid, can slow a process that may lead to the development and progression of many cancer types called DNA methylation.
Even more recently, scientists have found links between drinking coffee and reduced risk of breast and prostate cancer progression or recurrence.
In August 2013, scientists from the Fred Hutchinson Cancer Research Center reported that they had found an association between coffee consumption and a lower risk of prostate cancer recurrence and progression. Study results were published online ahead of print in the journal Cancer Causes & Control.
This study showed that coffee might not only prevent prostate cancer but help to control it in men who already had the disease. The researchers built on findings from the Harvard’s Health Professionals Follow-up Study, which showed that men who drank six or more cups of coffee per day had a 60 percent decreased risk of metastatic/lethal prostate cancer as compared to coffee abstainers.
The study was led by Janet L. Stanford, Ph.D., co-director of the Program in Prostate Cancer Research in the Fred Hutch Public Health Sciences Division. Stanford and colleagues found that men who drank four or more cups of coffee per day experienced a 59 percent reduced risk of prostate cancer recurrence and/or progression as compared to those who drank only one or fewer cups per week.
They did not, however, find an association between coffee drinking and reduced mortality from prostate cancer. That may simply be a matter of numbers, the researchers note. The study included too few men who died of prostate cancer to address that issue separately.
The researchers emphasized that a randomized clinical trial demonstrating the preventive effect is needed before coffee or specific coffee components can be recommended for secondary prevention of prostate cancer.
Need to Know: What is moderate coffee consumption?
Most studies of coffee’s effect on health rely on a standard of “moderate coffee consumption,” which may vary slightly from study to study. Generally, however, moderate coffee consumption is defined as 250 milligrams per day, equivalent to three 8-ounce servings of coffee.
Similarly, coffee may play a role in preventing recurrence of previously treated breast cancers, especially in women being treated with the estrogen-inhibiting drug Tamoxifen. Tamoxifen is used to treat early breast cancer in women and advanced breast cancer in men and women.
Researchers from Lund University in Sweden found that breast cancer survivors who were taking Tamoxifen were half as likely to have a recurrence of cancer if they drank two or more cups of coffee daily than were women who drank one cup or less. While researchers weren’t sure how coffee interacted with the treatment, they theorized that coffee could 'activate' Tamoxifen and make it more efficient, Maria Simonsson, doctoral student in Oncology at Lund University, said in a press release.
Need to Know: Does Coffee Prevent Breast Cancer?
Although several studies have suggested an association between moderate-to-high coffee consumption and reduced risk of breast cancer, a 2012 meta-analysis of 28 studies that probed possible links between drinking coffee and the risk of developing breast cancer did not find a correlation.
Could Coffee Prevent Heart Disease?
In the past, physicians and researchers have expressed a concern about caffeine and other stimulants in coffee and their effects on the heart. But according to a paper published in July 2013 in the Journal of the American College of Cardiology, drinking coffee may actually help protect our hearts.
For the paper, a research team from the Mid America Heart Institute at Saint Luke's Hospital of Kansas City and University of Missouri-Kansas City reviewed research on coffee and common measures of heart health including cholesterol, blood pressure, irregular heartbeat, and blood sugar levels. The team, led by James O’Keefe, director of the Preventive Cardiology Fellowship Program at the Saint Luke’s Mid America Heart Institute, found that in most cases, that cup of java could have good effects on your heart:
- Cholesterol: Filtered coffee does not affect cholesterol levels. Boiled coffee, on the other hand, can contain a cholesterol-raising compound called diterpenes.
- Blood pressure: Even six cups a day of regular, caffeinated coffee did not increase blood pressure levels over the long term.
- Irregular heartbeat: Despite widespread belief that the caffeine in coffee may increase risk of irregular heartbeat (arrhythmia), O’Keefe’s team found that coffee drinkers had no more risk of arrhythmia than non-drinkers. In fact, they found that arrhythmia risk may actually decrease in people who drink coffee daily.\
- Blood sugar: The researchers findings confirmed other work showing that antioxidants in both caffeinated and decaffeinated coffee seem to help control blood sugar and reduce risk for type 2 diabetes. Even a cup a day seemed to be effective.
Overall, the researchers found that one to two cups of coffee per day or more may decrease risk for heart disease and stroke. Their study also confirmed Freund’s findings that drinking coffee may decrease risk of death from both heart disease and other causes.
How Safe is Coffee?
Coffee consumption, especially at the 6-7 cup per day levels consumed by participants in many of the studies, can also have side effects. In most cases, those side effects are simply uncomfortable. Too much caffeine of any sort can lead to feelings of jitteriness, interrupted sleep, and irritability. For individuals who experience these side effects, decaffeinated coffee may be a good option.
Need to Know: Coffee's Nutrition Score
Coffee's nutritional value is close to zero. It shouldn't replace other healthful beverages like water, milk, and juice in your diet.
In some instances, drinking too much coffee could be risky:
- People who drink 6 or more cups of unfiltered coffee may experience a mild increase in cholesterol levels. So those with high cholesterol levels should stick with filtered coffee and avoid the boiled (Turkish, Greek, and “cowboy” coffees) versions.
- Even moderate coffee consumption – two to three cups per day – in people who have a genetic mutation that causes the body to break down caffeine more solely may be at increased risk of heart disease.
- For some people with diabetes, caffeine can affect blood sugar levels. According to the American Diabetes Association, some research suggests that people with diabetes who drink four or more cups per day of coffee may experience higher blood sugar levels after meals. However, they caution, the research is not conclusive enough to recommend a certain amount of caffeine for people with diabetes.
- The American College of Obstetricians and Gynecologists (ACOG) encourages women who are pregnant to limit caffeine intake to 200 milligrams per day. According to their position statement on caffeine and pregnancy, caffeine consumption at this level “does not appear to be a major contributing factor in miscarriage or preterm birth.” However, they characterize the relationship of caffeine to growth restriction as “undetermined” and state that “A final conclusion cannot be made at this time as to whether there is a correlation between high caffeine intake and miscarriage.” Caffeine crosses the placenta and increases levels of stress hormones called catecholamines in the mother, which may affect the fetus in unknown ways.
Need to Know: Does Coffee Cause Dehydration?
Consumers are often cautioned that the caffeine in coffee may cause dehydration because it triggers diuresis (the need to urinate).
However, a 2002 review of available literature on caffeine and fluid called this standard advice into question. The review showed that when people who didn't usually use caffeine consumed 250-300 mg of caffeine -- the amount found in 2-3 cups of coffee -- their urine output increased for the next hour or so. However, most people quickly became tolerant of the diuretic and other effects of caffeine if they continued to drink coffee or tea.
The researchers concluded that “Doses of caffeine equivalent to the amount normally found in standard servings of tea, coffee and carbonated soft drinks appear to have no diuretic action.”
While coffee itself contains no calories, it can be a diet-buster if you add goodies like sugar and cream. The calories in specialty coffee drinks can add up especially quickly. That bottled Starbucks mocha caramel latte contains 200 calories, about one-tenth of the average woman’s daily recommended intake. Prefer the fresh-brewed version? How about a 16-ounce Starbucks Caramel Frappuccino with whipped topping and caramel sauce for 430 calories?
In short, while coffee may not be the magic elixer of youth, it does appear to have some benefits for health when drunk in moderation. For most healthy adults, drinking about 3 cups of coffee (about 250-300 milligrams of caffeine) a day appears to be safe and potentially healthful.
You mean I can have three? Back to the coffee shop!
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Freedman, N.D. Park, Y. Abnet, C.C., Hollenbeck, A.R., and Sinha, R. Association of Coffee Drinking with Total and Cause-Specific Mortality. N Engl J Med 2012; 366:1891-1904. DOI: 10.1056/NEJMoa1112010. http://www.nejm.org/doi/full/10.1056/NEJMoa1112010
Huxley R, Lee CM, Barzi F, Timmermeister L, Czernichow S, Perkovic V, Grobbee DE, Batty D, Woodward M. Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis. Arch Intern Med. 2009 Dec 14;169(22):2053-63. doi: 10.1001/archinternmed.2009.439. Review. PubMed PMID: 20008687.
Salazar-Martinez, E., et al. Coffee consumption and risk for Type 2 diabetes. Annals of Internal Medicine, 2004, 140:1, pp.1-8.
Simonsson, M., Söderlind, V., Henningson, M., Hjertberg, M., Rose, C., Ingvar, C., and Jernström H. Coffee prevents early events in tamoxifen-treated breast cancer patients and modulates hormone receptor status. Cancer Causes & Control, 2013; 24 (5): 929 DOI: 10.1007/s10552-013-0169-1
van Dam RM, Feskens EJ. Coffee consumption and risk of type 2 diabetes mellitus. Lancet. 2002; 360:1477.-8
O'Keefe JH, Bhatti SK, Patil HR, Dinicolantonio JJ, Lucan SC, Lavie CJ. Effects of Habitual Coffee Consumption on Cardiometabolic Disease, Cardiovascular Health, and All-cause Mortality. J Am Coll Cardiol. 2013 Jul 3. doi:pii: S0735-1097(13)02601-6. 10.1016/j.jacc.2013.06.035. [Epub ahead of print]
Image credit: ariwasabi / 123RF Stock Photo