Study: Coffee Consumption Linked to Reduced Risk of Acute Kidney Injury

If you need another reason to start the day drinking a cup of joe, a recent study by Johns Hopkins Medicine researchers has revealed that consuming at least one cup of coffee a day may reduce the risk of acute kidney injury (AKI) when compared to those who do not drink coffee.

The findings, published in the journal Kidney International Reports, show that those who drank any quantity of coffee every day had a 15% lower risk of AKI, with the largest reductions observed in the group that drank two to three cups a day (a 22%–23% lower risk).

“We already know that drinking coffee on a regular basis has been associated with the prevention of chronic and degenerative diseases including type 2 diabetes, cardiovascular disease and liver disease,” says study corresponding author Chirag Parikh, M.D., Ph.D., director of the Division of Nephrology and professor of medicine at the Johns Hopkins University School of Medicine. “We can now add a possible reduction in AKI risk to the growing list of health benefits for caffeine.”

AKI, as described by the National Kidney Foundation, is a “sudden episode of kidney failure or kidney damage that happens within a few hours or a few days.” This causes waste products to build up in the blood, making it hard for kidneys to maintain the correct balance of fluids in the body.

AKI symptoms differ depending on the cause and may include: too little urine leaving the body; swelling in the legs and ankles, and around the eyes; fatigue; shortness of breath; confusion; nausea; chest pain; and in severe cases, seizures or coma. The disorder is most commonly seen in hospitalized patients whose kidneys are affected by medical and surgical stress and complications.

Using data from the Atherosclerosis Risk in Communities Study, an ongoing survey of cardiovascular disease in four U.S. communities, researchers assessed 14,207 adults recruited between 1987 and 1989 with a median age of 54. Participants were surveyed seven times over a 24-year period as to the number of 8-ounce cups of coffee they consumed per day: zero, one, two to three, or more than three. During the survey period, there were 1,694 cases of acute kidney injury recorded.

When accounting for demographic characteristics, socioeconomic status, lifestyle influences and dietary factors, there was a 15% lower risk of AKI for participants who consumed any amount of coffee versus those who did not. When adjusting for additional comorbidities — such as blood pressure, body mass index (BMI), diabetes status, use of antihypertensive medication and kidney function — individuals who drank coffee still had an 11% lower risk of developing AKI compared with those who did not.

“We suspect that the reason for coffee’s impact on AKI risk may be that either biologically active compounds combined with caffeine or just the caffeine itself improves perfusion and oxygen utilization within the kidneys,” says Parikh. “Good kidney function and tolerance to AKI — is dependent on a steady blood supply and oxygen.”

More studies are needed, Parikh says, to define the possible protective mechanisms of coffee consumption for kidneys, especially at the cellular level.

“Caffeine has been postulated to inhibit the production of molecules that cause chemical imbalances and the use of too much oxygen in the kidneys,” he explains. “Perhaps caffeine helps the kidneys maintain a more stable system.”

Parikh and his colleagues note that coffee additives such as milk, half-and-half, creamer, sugar or sweeteners also could influence AKI risks and warrant further investigation. Additionally, the authors say that consumption of other types of caffeinated beverages, such as tea or soda, should be considered as a possible confounding factor.

Source: Johns Hopkins Medicine

Will Coffee Raise Your Cholesterol?

Amy Norton wrote . . . . . . . . .

People who rely on coffee for a pick-me-up may also see a boost in their cholesterol levels — especially if they sip an unfiltered variety, a new study suggests.

The researchers found that among more than 21,000 Norwegian adults, those who indulged in several cups of coffee a day generally had slightly higher cholesterol than non-drinkers. The extent of the difference, however, depended on brewing method.

People who drank the “least filtered” kinds of coffee — made with a French press, for example — showed the largest cholesterol effects: On average, those who drank six or more cups a day had total cholesterol levels that were eight to 12 points higher, versus non-drinkers.

Espresso lovers were next, followed by women who drank filtered drip coffee (with no cholesterol effects seen among their male counterparts).

The findings are in line with past studies suggesting that unfiltered coffee might have a particular effect on cholesterol levels, according to researcher Dr. Maja-Lisa Løchen.

Unfiltered brews include coffees that are boiled or made using a French press or “plunger.” Espresso also falls into that category, but it is relatively more filtered than the other varieties, said Løchen, a professor at UiT The Arctic University of Norway.

Brewing methods matter because coffee contains natural oils that can raise blood cholesterol. Researchers have long known that unfiltered coffees, by exposing the grounds to hot water for a prolonged time, contain more of those oils.

In fact, Løchen said, it was the Tromsø Study from Norway that first showed, in the 1980s, that “it’s all in the brewing.”

In those days, she noted, boiled coffee was the unfiltered variety of choice. But now espresso and plunger coffees are all the rage, so Løchen and her colleagues used more recent data from the Tromsø Study to look at the relationship between those brews and blood cholesterol.

“Norwegians love coffee,” Løchen said, “and Norway has the second highest coffee consumption in the world.”

The findings, published online in the journal Open Heart, are based on more than 21,000 adults aged 40 and up who reported on their coffee drinking habits, exercise levels and alcohol intake.

On average, study participants drank four to five cups of coffee a day. Those who indulged in boiled or French press coffee — six or more cups a day — showed the biggest cholesterol elevations, relative to non-drinkers, the findings showed.

Next came people who said they downed three to five cups of espresso a day. Their total cholesterol was roughly 4 to 6 mg/dL higher, versus people who did not drink espresso. Finally, women who drank at least six cups of filtered coffee each day had cholesterol levels that were 4 mg/dL higher, on average, versus women who never drank filtered coffee.

However, a registered dietitian who was not involved in the study had some caveats.

For one thing, there was no information on participants’ overall diet, said Connie Diekman, a food and nutrition consultant and former president of the Academy of Nutrition and Dietetics.

Nor is it clear whether people regularly doused their coffee of choice with sugar and cream, Diekman pointed out.

So, she said, the question remains, was it the coffee, the cream or the foods people consumed with all those cups of coffee?

“Coffee, in and of itself, is likely a very small player in elevating cholesterol,” Diekman said. “So rather than worry about how coffee might be impacting cholesterol, look at your whole diet and establish other healthful life behaviors.”

Løchen also pointed to the bigger picture, noting that moderate coffee intake (up to five cups a day) has been linked to a lower risk of heart disease and a longer life.

Angel Planells is a Seattle-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. He said that filtered or instant coffees might be the best choices for people watching their cholesterol. But again, overall diet and lifestyle are key.

If you really enjoy that latte or mocha, Planells said, there may be other ways to trim some “bad” fat from your diet — like cutting down on processed meat or fried foods.

That said, some people should be especially mindful about the caffeine in coffee, Planells said — including pregnant women and anyone with potential caffeine side effects, like trouble sleeping or the “jitters.”

Source: HealthDay

Could Coffee or Tea Lower Your Odds for Dementia and Stroke?

Alan Mozes wrote . . . . . . . . .

A few cups of your favorite brew — coffee or tea — each day might help keep stroke and dementia at bay, a large new study suggests.

For close to 14 years, scientists stacked up coffee and tea consumption against the risk of stroke and dementia among nearly 366,000 healthy Brits between 50 and 74 years of age.

The researchers — led by Yuan Zhang of Tianjin Medical University in Tianjin, China — observed that those who drank 2 to 3 cups of coffee along with the same amount of tea every day had a 32% lower risk for stroke, and a 28% lower risk for dementia, compared to those who drank neither.

But don’t toast the news with a big jolt of caffeine just yet.

The findings don’t prove that coffee and tea protect against either stroke or dementia — only that there is an association.

“People need to remember that an association does not guarantee that the same outcome will happen” for everyone, said Connie Diekman, a former president of the Academy of Nutrition and Dietetics who reviewed the findings. The Chinese study team offered the same caution.

Data about study participants came from the UK Biobank, which collected health information from 22 care centers in the United Kingdom.

Enrollment — at an average age of 60 — began between 2006 and 2010. Participants completed questionnaires about their coffee and tea habits. Their stroke and dementia risk was tracked until 2020.

About a fifth of the participants drank no coffee at all, and about 14% drank no tea. The largest group –16% — reported drinking between a half-cup and 1 cup of coffee a day and roughly 4 cups of tea. About 14% said they drank a similar amount of tea but no coffee.

Finally, 12% said they drank 2 to 3 cups of both coffee and tea daily.

During the follow-up period, 10,053 participants (2.7%) had a stroke, and 5,079 (1.4%) developed dementia.

And drinking coffee — even in very small amounts — was linked to a lower risk for both. The same was true of tea.

The lowest risk for stroke and dementia was seen among participants who downed either 2 to 3 cups of coffee daily, 3 to 5 cups of tea, or a combined 4 to 6 cups of both.

While lower risk was seen for ischemic strokes resulting from a blood clot or narrowed arteries, there was no reduction in risk for a less common form of stroke (hemorrhagic) that results from blood vessel breakage.

So what’s likely protective about coffee or tea?

A previous study pointed both to “caffeine and the antioxidant actions provided by the plants that coffee and tea come from,” said Diekman, a St. Louis food and nutrition consultant and sports dietitian.

“It appears from this [new] study that the mechanism is once again the caffeine and the antioxidant action,” she said. “This finding certainly supports what we know about so many plant foods: They offer many health-related benefits beyond just the vitamins and minerals they contain.”

Another U.S. expert agreed, noting that coffee and tea contain several chemical compounds, not just caffeine, which have health benefits.

“There are many possibilities of how these chemicals could work in the body, from antioxidants, anti-inflammation, increase blood flow, protect blood vessels from damage, and so on,” said Lona Sandon, an associate professor and program director in clinical nutrition at University of Texas Southwestern Medical Center in Dallas. “These effects could influence risk of dementia or stroke.”

Neither Sandon nor Diekman was particularly concerned about the quantity of coffee or tea in question.

Sandon noted that 4 to 6 cups is fairly common in many countries, while Diekman noted that current guidelines indicate that 3 to 5 (8-ounce) cups of coffee a day appear to be safe for most adults.

The point now is whether non-drinkers should start based on these findings, Diekman said.

“That question,” she said, “still needs more research.”

The findings were reported in PLOS Medicine.

Source: HealthDay

Drinking Caffeinated Coffee Has Both Beneficial and Harmful Short-term Health Effects

Drinking caffeinated coffee appears to have both beneficial and harmful short-term health effects: increased abnormal heartbeats, increased physical activity and reduced sleep duration, according to late-breaking research presented at the American Heart Association’s Scientific Sessions 2021.

“Coffee is the most commonly consumed beverage in the world, yet its health effects remain uncertain,” said study author Gregory Marcus, M.D., M.A.S., associate chief of cardiology for research and endowed professor of atrial fibrillation research at the University of California, San Francisco. “While the majority of long-term observational studies have suggested multiple potential benefits of drinking coffee, this is the first randomized trial to investigate the real-time, physiologic consequences of coffee consumption.”

Marcus and colleagues enrolled 100 adult volunteers, and they were assigned to wear continuously recording ECG devices (to track heart rhythm), wrist-worn devices to track physical activity and sleep; and continuous glucose monitors to track blood sugar levels for two weeks. The participants were an average age of 38 years, 51% were women and 48% were white. Researchers also obtained DNA saliva samples from the participants to assess genetic variants that may affect caffeine metabolism.

Participants were then randomly assigned to either avoid or consume coffee for no more than two consecutive days each for 14 consecutive days. Coffee and espresso consumption were recorded in real time via a “time stamp button” on the ECG monitor, and researchers tracked trips to coffee shops with geotracking. In addition, participants completed daily questionnaires to detail how much coffee they had consumed every morning.

The analysis found that coffee consumption was associated with a 54% increase in premature ventricular contractions, a type of abnormal heartbeat originating in the lower heart chambers reported to feel like a skipped heartbeat. In contrast, drinking more coffee was associated with fewer episodes of supraventricular tachycardia, an abnormally rapid heart rhythm arising from the upper heart chambers.

Consuming coffee was consistently associated with more physical activity as well as less sleep. Specifically:

  • Participants who consumed coffee logged more than 1,000 additional steps per day compared to days when they did not drink coffee.
  • On the days participants drank coffee, they had 36 fewer minutes of sleep per night according to their Fitbit devices.
  • Drinking more than one coffee drink more than doubled the number of irregular heartbeats arising from the heart’s lower chambers.
  • Each additional cup of coffee consumed was associated with nearly 600 more steps per day and 18 fewer minutes of sleep per night.
  • There were no differences in continuously recorded glucose measured when the study participants consumed versus avoided coffee.

These findings were corroborated by analyses of adherence to their randomization assignment and amplified when more versus less coffee was consumed.

“More physical activity, which appears to be prompted by coffee consumption, has numerous health benefits, such as reduced risks of Type 2 diabetes and several cancers, and is associated with greater longevity,” Marcus said. “On the other hand, reduced sleep is associated with a variety of adverse psychiatric, neurologic and cardiovascular outcomes. More frequent abnormal heartbeats from the upper heart chambers influence risk of atrial fibrillation, and more frequent abnormal beats from the lower chambers, or ventricles, increase the risk of heart failure. These results highlight the complex relationship between coffee and health.”

The study participants with genetic variants associated with faster caffeine metabolism exhibited more abnormal heart beats originating in the ventricles, or PVCs, when more caffeinated coffee was consumed. The slower an individual metabolized caffeine based on their genetics, the more sleep they lost when they drank caffeinated coffee.

The investigators also sought to determine if changes in exercise or sleep influenced coffee’s effects on abnormal heart rhythms, and no such association was identified.

Marcus noted that because coffee was randomly assigned to the study participants, cause-and-effect can be inferred. These observations were made during repeated assessments of days when coffee was consumed versus when it was not for each study participant, eliminating concerns regarding differences in individual-level characteristics as an explanation for these results.

Source: American Heart Association

Daily Coffee May Protect the Heart

Steven Reinberg wrote . . . . . . . . .

The latest buzz on coffee? It may be good for your heart, a new, large study suggests.

Drinking light to moderate amounts — up to three cups a day — may lower the risk of stroke, fatal heart disease and all-cause death, researchers found.

“Regular coffee consumption of up to three cups per day is associated with a lower risk of all-cause mortality, cardiovascular mortality and stroke,” said lead researcher Dr. Judit Simon, from the Heart and Vascular Center at Semmelweis University in Budapest, Hungary.

These benefits might be partly explained by positive alterations in heart structure and function, she said.

Better yet, all types of coffee — caffeinated, decaf, brewed and instant — may offer heart benefits, Simon said.

“In a sub-analysis on types of mostly consumed coffee, decaffeinated coffee was associated with lower risk of all-cause and cardiovascular deaths, but not with lower stroke incidence, suggesting that caffeine is not the main or only component that is responsible for these favorable outcomes,” she said.

Instant coffee was associated with a lower risk of all-cause death, while ground coffee was linked with reduced risk of all-cause and cardiovascular death and lower stroke incidence, she said.

For the study, Simon and her colleagues collected data on nearly 470,000 men and women listed in the U.K. Biobank. At the study’s start, participants had no signs of heart disease and were an average age of 56. They were followed for up to 15 years.

Compared with non-coffee drinkers, those who drank light to moderate amounts had a 12% lower risk of all-cause death. Their odds for stroke were reduced by 21% and fatal heart disease by 17%, the researchers found, though only an association rather than a cause-and-effect link was seen.

The findings remained after the researchers accounted for age, sex, weight, height, smoking status, physical activity, high blood pressure, diabetes, cholesterol, income and diet.

Using cardiac MRIs, Simon’s group also looked at the effect daily coffee consumption had on the structure and function of the heart among nearly 31,000 people who were followed for 11 years on average.

They found that compared with not drinking coffee regularly, those who drank coffee daily had healthier, better-functioning hearts.

One U.S. heart expert looked over the findings.

“A significant number of observational studies have suggested that regular consumption of coffee is associated with lower risk of cardiovascular events, cardiovascular death and all-cause mortality,” said Dr. Gregg Fonarow, director of the Ahmanson-UCLA Cardiomyopathy Center in Los Angeles.

These findings add to the body of evidence that coffee consumption, even three to five cups a day, appears to be safe and associated with cardiovascular benefits, he said.

“Potential mechanisms which may account for potential benefits include improved insulin sensitivity, reduced inflammation, improved liver function and antioxidant effects,” Fonarow said. “However, it is important to note that these findings have not been established by prospective randomized clinical trials, so should be interpreted with caution.”

The findings were presented online at the annual meeting of the European Society of Cardiology, but should be considered preliminary until published in a peer-reviewed medical journal. The study received no funding from the coffee industry.

Source: American Heart Association