Drinking coffee is "more likely to benefit health than to harm it" for a range of health outcomes, say researchers in The BMJ medical journal recently. They bring together evidence from over 200 studies and find that drinking three to four cups of coffee a day is associated with a lower risk of death and getting heart disease compared with drinking no coffee.
Coffee drinking is also associated with lower risk of some cancers, diabetes, liver disease and dementia. However, they say drinking coffee in pregnancy may be associated with harms, and may be linked to a very small increased risk of fracture in women.
Coffee is one of the most commonly consumed beverages worldwide and could have positive health benefits. But existing evidence is of lower quality from observational research so randomized controlled trials are needed to strengthen the evidence of benefits. The included studies used mainly observational data, providing lower quality evidence, so no firm conclusions can be drawn about cause and effect, but their findings back up other recent reviews and studies of coffee intake.
To better understand the effects of coffee consumption on health, a team led by Dr. Robin Poole, Specialist Registrar in Public Health at the University of Southampton, with collaborators from the University of Edinburgh, carried out an umbrella review of 201 studies that had aggregated data from observational research and 17 studies that had aggregated data from clinical trials across all countries and all settings.
Drinking coffee was consistently associated with a lower risk of death from all causes and from heart disease, with the largest reduction in relative risk of death at three cups a day, compared with non-coffee drinkers. Increasing consumption to above three cups a day was not associated with harm, but the beneficial effect was less pronounced.
Coffee was also associated with a lower risk of several cancers, including prostate, endometrial, skin and liver cancer, as well as type 2 diabetes, gallstones and gout. The greatest benefit was seen for liver conditions, such as cirrhosis of the liver.
Finally, there seemed to be beneficial associations between coffee consumption and Parkinson's disease, depression and Alzheimer's disease. There was less evidence for the effects of drinking decaffeinated coffee but it had similar benefits for a number of outcomes.
Safe, Moderate Coffee Consumption
Many of the included studies may have adjusted for factors that may be associated with both the health outcome and with coffee drinking, such as smoking. This was not comprehensive and varied from study to study. The authors can therefore not rule out the effect of such factors on the apparent harmful or beneficial associations.
The authors conclude that coffee drinking "seems safe within usual patterns of consumption, except during pregnancy and in women at increased risk of fracture." And they call for robust randomized controlled trials "to understand whether the key observed associations are causal."
In a linked editorial, Eliseo Guallar at the Johns Hopkins Bloomberg School of Public Health says, although we can be reassured that coffee intake is generally safe, doctors should not recommend drinking coffee to prevent disease and people should not start drinking coffee for health reasons.
As this study shows, some people may be at higher risk of adverse effects, and there is "substantial uncertainty" about the effects of higher levels of intake. Finally, coffee is often consumed with products rich in refined sugars and unhealthy fats, "and these may independently contribute to adverse health outcomes," Guallar adds. However, even with these caveats, moderate coffee consumption seems remarkably safe, and it can be incorporated as part of a healthy diet by most of the adult population.
Higher Coffee Consumption Associated With Lower Risk Of Early Death
A similar study recently stated that higher coffee consumption is associated with a lower risk of death, according to research presented recently at the ESC Congress. The observational study in nearly 20,000 participants suggests that coffee can be part of a healthy diet in healthy people.
"Coffee is one of the most widely consumed beverages around the world," says Dr. Adela Navarro, a cardiologist at Hospital de Navarra, Pamplona, Spain. "Previous studies have suggested that drinking coffee might be inversely associated with all-cause mortality but this has not been investigated in a Mediterranean country."
Mediterranean Diet Study
The purpose of the study was to examine the association between coffee consumption and the risk of mortality in a middle-aged Mediterranean cohort. The study was conducted within the framework of the Seguimiento Universidad de Navarra (SUN) Project, a long-term prospective cohort study in more than 22,500 Spanish university graduates which started in 1999. This analysis included 19,896 participants of the SUN Project, whose average age at enrollment was 37.7 years old. Patients were followed-up for an average of 10 years.
During the 10-year period, 337 participants died. The researchers found that participants who consumed at least four cups of coffee per day had a 64% lower risk of all-cause mortality than those who never or almost never consumed coffee. There was a 22% lower risk of all-cause mortality for each two additional cups of coffee per day.
The researchers examined whether sex, age or adherence to the Mediterranean diet had any influence on the association between baseline coffee consumption and mortality. They observed a significant interaction between coffee consumption and age. In those who were at least 45 years old, drinking two additional cups of coffee per day was associated with a 30% lower risk of mortality during follow-up. The association was not significant among younger participants.
"In the SUN project we found an inverse association between drinking coffee and the risk of all-cause mortality, particularly in people aged 45 years and above, Navarro said. This may be due to a stronger protective association among older participants. Our findings suggest that drinking four cups of coffee each day can be part of a healthy diet in healthy people."
Ground Coffee Improves Nose, Throat Surgery
Imagine plopping six cups of coffee grounds on the heads of patients just before they are wheeled into the operating room to have nose or throat surgery? In essence, that is what a team of Vanderbilt University engineers proposed in an effort to improve the reliability of the sophisticated GPS system that surgeons use for these operations. They have designed a granular jamming cap filled with coffee grounds that does a better job of tracking patient head movements than current methods.
The coffee grounds are not loose but form a thin layer inside a stretchy silicone headpiece, which looks something like a black latex swim cap decorated with reflective dots. After the cap is placed on the patients head, it is attached to a vacuum pump that sucks the air out of the cap, jamming the tiny grounds together to form a rigid layer that conforms closely to the shape of the patients head. This is the same effect that turns vacuum-packed coffee into solid bricks.
The Registration Process
Before surgery, a special scanner is used to map the location of the dots relative to key features on the patients head: a process called registration. Then, during surgery an overhead camera observes the position of the dots allowing the navigation system to accurately track the position of the patients head when the surgeon repositions it. The computer uses this information to combine a CT scan, which provides a detailed 3-D view of the bone and soft tissue hidden inside the patients head, with the position of the instruments the surgeon is using and displays them together in real time on a monitor in the operating room.
These are very delicate operations and a sophisticated image guidance system has been developed to help the surgeons, but they don't trust the system because sometimes it is spot-on and other times it is off the mark, says Robert Webster, associate professor of mechanical engineering and otolaryngology, who is developing a surgical robot designed specifically for endonasal surgery. When we heard about this, we began wondering what was causing these errors and we decided to investigate.
When Webster and his research team looked into the matter, they were surprised by what they found. They discovered it wasn't the hardware or the software in the guidance system that was causing the problem. It was the way the reflective markers were attached to the patients head that was at fault. Typically, these fiducial markers are attached by an elastic headband and double-backed tape and are subject to jarring and slipping. Their tests found that skin movement and accidental bumps by operating room staff both produced large tracking errors.
The basic assumption is that, after registration, the spatial relationships between the patients head and the fiducial markers remains constant, says Patrick Wellborn, the graduate student making the presentation. Unfortunately, that is not the case. For one thing, studies have shown that the skin on a persons forehead can move as much as a half an inch relative to the skull. And accidentally bumping or dragging cables over the headband can also produce significant targeting errors.
Previous research has found that when everything goes well, the guidance system produces targeting errors of about two millimeters but, in about one operation out of seven, the target error is much larger, forcing the surgeon to redo the registration process.
The Coffee Ground Method
So the team began thinking up alternative, non-invasive methods to attach these critical markers. Webster recalled some experiments that were done using coffee grounds to help robots grip irregularly shaped objects. Bladders filled with coffee grounds were built into the robots gripper. When it grabbed an object, the bladders conformed to its shape. Then a vacuum was pulled and the coffee grounds became rigid and locked the object into place. The researchers decided to see if this technique could be applied to the problem.
In the last three years, they have gone through a number of designs. They began with headbands that had coffee-ground-filled bags over the temples. Their tests showed that these models could reduce the targeting error by about 50 percent. But the engineers still weren't satisfied.
Then, Wellborn, who was taking over the project, had a brainstorming session with fellow graduate student Richard Hendrick. Among the materials that his predecessor had left behind was a latex bald cap. That sparked the idea of caps in general, Wellborn recalled. We wanted something elastic that was form fitting, which led to the idea of a swim cap.
New Design And Advantage
In addition to fitting extremely tightly to the head, the new design had another advantage. The headband system has only three fiducial markers attached on the ends of three thin rods to form a triangle. The new design allowed them to attach several dozen markers directly to the surface of the cap, which the researchers believe will also contribute to improving the guidance systems accuracy.
They designed three tests to determine how well this granular jamming cap performed relative to the current headband in reducing targeting error. They bumped both of them from a number of different directions with a tennis ball filled with plastic particles swinging on the end of a string. They found that the cap reduced targeting errors by 83 percent.
They simulated the case where a cable or other piece of equipment is accidentally pushed against the two by applying forces ranging from four to six pounds in different directions. They determined that the cap outperformed the headband by 76 percent when the forces were applied to the headband and by 92 percent when they were applied to the markers.
They tested the effects of head repositioning by having an experienced surgeon reposition test subjects heads six to seven times. In this case, the cap proved to have 66 percent lower error rates than the headband.
Its a very clever way - that doesn't involve drilling holes in patients skulls - to greatly improve the accuracy of the guidance system when we are operating in the middle of a persons skull: a zone where the accuracy of the current system is inadequate, added Assistant Professor of Otolaryngology Paul Russell, who is collaborating with the engineers on the project.
Does Roasting Affect Coffee's Properties?
In June 2017, researchers compared the caffeine and chlorogenic acid components of coffee beans at different roasting levels and tested the protective antioxidant and anti-inflammatory properties of the different coffee extracts in human cell models. The results, linking degrees of roasting to reduced antioxidant and anti-inflammatory activities, were published in the Journal of Medicinal Food. The article is entitled Cellular Antioxidant and Anti-inflammatory Effects of Coffee Extracts with Different Roasting Levels.
The researchers measured the levels of caffeine and chlorogenic acid and evaluated the effects of Coffea Arabica green coffee extracts roasted at levels corresponding to light, medium, city, and French roast. Whereas the caffeine levels did not differ greatly between the various roasting levels, the levels of chlorogenic acid did vary and correlated with the differences shown in antioxidant and anti-inflammatory activity.
"When people think of coffee, they often associate the beverage with caffeine. However, coffee beans have many other chemicals that could help fight chronic inflammatory diseases," says Journal of Medicinal FoodEditor-in-Chief Sampath Parthasarathy, MBA, PhD., Florida Hospital Chair in Cardiovascular Sciences and Interim Associate Dean, College of Medicine, University of Central Florida. "Coffee drinkers are passionate about different roasts - light, medium and dark. This study suggests that some of the potentially beneficial compounds could be affected by the roasting process. This article would certainly change my coffee roast preference!"
Substance In Coffee Delays Onset Of Diabetes
In recent years, researchers have identified substances in coffee that could help quash the risk of developing type 2 diabetes. But few of these have been tested in animals. Recently, a study in ACS'Journal of Natural Products reports that one of these previously untested compounds appears to improve cell function and insulin sensitivity in laboratory mice. The finding could spur the development of new drugs to treat or even prevent the disease.
Some studies suggest that drinking three to four cups of coffee a day can reduce the risk of developing type 2 diabetes. Initially, scientists suspected that caffeine was responsible for this effect. But later findings discounted this possibility, suggesting that other substances in coffee may have a more important role.
In a previous laboratory study, Fredrik Brustad Mellbye, Sren Gregersen and colleagues found that a compound in coffee called cafestol increased insulin secretion in pancreatic cells when they were exposed to glucose. Cafestol also increased glucose uptake in muscle cells just as effectively as a commonly prescribed antidiabetic drug. In this new study, the researchers wanted to see if cafestol would help prevent or delay the onset of type 2 diabetes in mice.
The researchers divided mice that are prone to develop type 2 diabetes into three groups. Two of the groups were fed differing doses of cafestol. After 10 weeks, both sets of cafestol-fed mice had lower blood glucose levels and improved insulin secretory capacity compared to a control group, which was not given the compound.
Cafestol also didn't result in hypoglycemia, or low blood sugar, a possible side effect of some antidiabetic medications. The researchers conclude that daily consumption of cafestol can delay the onset of type 2 diabetes in these mice, and that it is a good candidate for drug development to treat or prevent the disease in humans.
Extra Coffee Calories
More than 160 million people in the U.S. drink coffee or tea on a regular basis, and many of them use sugar, cream, flavored syrups or other calorie-laden additives in their drinks of choice. A new analysis reveals just how much Americans are adding to their caloric intake by spicing up or sweetening their coffee or tea.
The research looked at 12 years of data - ending in 2012 - from the National Health and Nutrition Examination Survey, including information from a nationally representative sample of 13,185 adults who reported drinking coffee and 6,215 adults who reported drinking tea in the 24 hours prior to being surveyed.
The data suggests that more than 51 percent of U.S. adults drink coffee and nearly 26 percent drink tea on any given day, said University of Illinois kinesiology and community health professor Ruopeng An, who conducted the study. Roughly two-thirds of the coffee drinkers and one-third of the tea drinkers put sugar, cream, flavorings or other calorie-rich additives in their drinks, he found.
"Many people prefer drinking coffee and tea with sugar, cream, half-and-half or honey," An said. "These add-in items are often dense in energy and fat but low in nutritional value. Milk products add a bit of calcium to the diet, but the amount - 22 milligrams per day on average - is negligible. The daily recommended calcium intake is 1,000 to 1,300 milligrams, depending on one's age and pregnancy status.
Those who drink their coffee black consume about 69 fewer total calories per day, on average, than those who add sweeteners, cream or other substances to their coffee. More than 60 percent of those calories come from sugar, with fat accounting for most of the rest of the extra calories consumed.
Tea drinkers tend to add fewer calorie-dense substances to their tea if they add anything at all, the analysis found. "Compared with adding nothing to one's tea, drinking tea with caloric add-ins increased daily caloric intake by more than 43 calories, on average, with nearly 85 percent of those added calories coming from sugar," An said. "Our findings indicate that a lot of coffee and tea drinkers regularly use caloric add-ins to improve the flavor of their beverages, but possibly without fully realizing or taking into consideration its caloric and nutritional implications. The daily intakes may seem small, but the extra calories every day can add up to extra pounds.
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