Coffee and health: the limit of 4 cups

Coffee consumption is beneficial for health in terms of reducing the risk of premature mortality. However, in case of abuse, caffeine can become harmful to the cardiovascular system.

Two very large studies provide an update on the subject.
  •  An American team (Harvard University) cross-referenced and analyzed data from about 40 studies involving a total of nearly 4 million people. She observes that the lowest relative risk (-15%) of premature mortality from all causes is obtained with 3.5 cups of coffee per day, for cardiovascular mortality (-17%) it is 2.5 cups, and 2 cups for cancer mortality (-4%). Higher consumption is not associated with additional benefit. The protective effect is maintained after taking into account parameters such as age, body mass index (BMI), alcohol and tobacco consumption, and caffeine content of coffee. The ideal range is therefore 3 or 4 cups per day (which confirms the results of other work).
  •  An Australian team (University of South Australia) followed some 350,000 people aged 37 to 73. It establishes an association between moderate daily consumption of coffee (with caffeine) and protection against cardiovascular disease, already from 1 - 2 cups per day. On the other hand, there is an opposite effect in case of excessive consumption: thus, beyond 6 cups, the cardiovascular risk increases on average by 22%, probably due to the influence of caffeine on blood pressure.

The recommendation: for those who enjoy coffee, drinking 3 or 4 cups a day is a good pace, but care should be taken not to exceed it.

Five health benefits of coffee

Drinking three to four coffees a day reduces the risk of early death and helps prevent certain diseases.

Long or tight, coffee is good for your health! This is revealed by a study conducted at the University of Southampton under the direction of Robin Pool, a public health specialist, published Wednesday, November 22 in the British Medical Journal. It compiles the results of more than 200 previous studies (meta-analysis). Scientists recommend drinking three to four cups of coffee a day (except for pregnant women or individuals prone to fractures) to reduce the risk of diabetes, liver disease, dementia and even the occurrence of certain cancers.

This publication is not the first to demonstrate the beneficial effects of coffee. Over the past ten years, numerous studies have confirmed the positive effects of safe coffee, including the prevention of cancer and cardiovascular diseases.

● Living longer

An American study published on July 11, 2017 revealed that people who drank one cup of coffee a day had a 12% reduced risk of dying during the study compared to those who did not drink coffee, a level that reached 18% for those who consumed three cups a day. The causes of death were weighted according to smoking and other confounding factors.

The same is true for a European study, published at the same time as the American study. By analysing the data of 520,000 participants over 35 years of age for 16 years, the researchers also conclude that consumers of about three cups of coffee per day, including decaffeinated coffee, seem to have a longer life expectancy than those who do not drink it.

Professor Elio Riboli, Head of the Faculty of Public Health at Imperial College London who participated in this work: "Although more research is needed, we can say that the results of this major European study confirm the findings of previous research around the world.
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● Preventing cancer

Moderate coffee consumption (3 to 4 cups per day) protects against the development of many cancers. "Overall, the effects of coffee diverge according to cancer. In some cases, coffee has no effect, but in others, it is protective. There are no cases where coffee is a factor that increases the risk of developing cancer," explains Dr Astrid Nehlig, research director at Inserm and author of the book "Coffee and Health, all about the multiple virtues of this beverage".

In a study published in 2011 in Cancer Epidemiology, Biomarkers & Prevention, for example, Harvard researchers claim that drinking 4 or more cups of coffee a day is associated with a 25% reduction in the risk of developing endometrial cancer. Drinking between 2 and 3 cups a day reduces this risk by 7%. Similarly, in 2013, the American Association of Gastroenterology pointed out that 3 cups of coffee per day halves the risk of developing liver cancer.

Many other cancers have been studied in similar studies and coffee reduces the risk of developing breast, prostate, pancreatic, skin and other cancers.

● Reduce cardiovascular diseases

"From the first cup, there is also a slight reduction in the risk of developing cardiovascular problems. And this effect is proven to be between 3 and 5 cups per day," explains Dr. Nehlig. In the study published by the journal Annals of Internal Medicine, conducted in the United States on more than 185,000 adults, the authors found a link between higher coffee consumption and a lower risk of death from cardiovascular disease, such as heart attack or cardiac arrest.

● Fewer type II diabetes

Coffee, consumed in large quantities this time, also has benefits for type 2 diabetes. A meta-analysis published in 2014 in Diabetes Care and involving more than one million participants concluded that "consuming 6 cups per day was associated with a one-third reduction in the risk of developing type 2 diabetes. Depending on the metabolism of each individual, however, it is recommended not to exceed 4 cups daily (about 400 mg of coffee per day) and even a low consumption of coffee, 2 cups per day, already reduces the risk of developing type 2 diabetes.

● Combating neurodegenerative diseases

Finally, studies have shown the positive effects on diseases of aging, such as Parkinson's or Alzheimer's. An article published in 2010, comparing the results of 26 studies, indicates that coffee drinkers are less likely to develop Parkinson's disease than non-drinkers. The higher the consumption, the less symptoms (tremors, muscle stiffness, etc.) will be spread.

Protection against neurodegenerative diseases is believed to be due to caffeine. In contrast to protection against other diseases, often linked to the action of antioxidants. "Very schematically, caffeine will have positive effects on all brain-related diseases (such as Alzheimer's or Parkinson's) and antioxidants will benefit almost all other organs, especially in cases of cancer," concludes Dr. Astrid Nehlig.

Drinking coffee would make you live longer

The health benefits of regular coffee consumption, long disputed, are confirmed by two new extensive studies, one conducted in ten European countries, including France, and the other in the United States. Since these are observational studies, however, they do not prove a causal relationship, warn researchers and independent experts.

The results of both studies, adjusted for risk factors such as smoking, were published yesterday in the American medical journal Annals of Internal Medicine.

Consumers of about three cups of coffee per day, including decaffeinated coffee, appear to have a longer life expectancy than those who do not drink coffee, according to the European study analysing data from 520,000 men and women over 35 years of age, followed by the European Cancer and Nutrition Survey (EPIC) for 16 years.

"We found that higher coffee consumption was associated with a lower risk of death from all causes, especially circulatory and digestive diseases," explains Marc Gunter of the International Agency for Research on Cancer and one of the main authors of this study.

This is the most extensive work ever carried out in Europe on the health and longevity effects of coffee, the world's most drunk beverage, with about 2.25 billion cups consumed daily. "These results were similar in the ten European countries with different consumption habits and cultures," says Marc Gunter.

The study "also provides important insights into possible mechanisms explaining the beneficial effects of coffee", excluding caffeine. Coffee is particularly rich in antioxidants, which play an important role in preventing cancer, researchers point out.

The second study was conducted in the United States on more than 185,000 adults of all origins, aged 45 to 75 years, over an average period of sixteen years. The authors found a link between higher coffee consumption and a lower risk of mortality from cardiovascular, respiratory, renal, cancer, diabetes and respiratory diseases.

More specifically, people who drank one cup of coffee a day were 12% less likely to die during the study than those who did not, a level that reached 18% for those who drank three cups. As in the European study, the effects were similar with decaffeinated coffee.

"You can't tell the public'drink coffee to prolong your life' but you can see a connection," says Veronica Setiawan, professor of preventive medicine at the University of Southern California and lead author of the research.

Marc Gunter, from the European study, is however a little more nuanced: "Since these are observational studies - which do not prove the cause-and-effect relationship - we cannot recommend drinking more or less coffee at this stage. But our results suggest that moderate consumption, up to three cups a day, can have beneficial health effects."

How many coffees before a health risk?

Notice to coffee lovers. If you can't do without your daily cups, drinking more than six a day is a strain on your heart, according to new Australian research.

"Coffee is the most consumed stimulant in the world - it wakes us up, stimulates our energy and helps us to concentrate - but people always ask: "At what level of caffeine is too much?", says Elina Hyppönen. The researcher at the Australian Centre for Precision Health looked at the risks of coffee consumption. Wake up bowl, espresso after eating, boost of 16 hours.... How many cups before the drink is harmful to health? The findings of the study were posted on the University of South Australia website on May 10.

With moderation

The scientists used data from 347,077 people aged 37 to 73 from the British Biobank. They looked at the genetic material of the participants, and their coffee consumption. Individuals carrying the CYP1A2 gene, for example, metabolize caffeine four times faster than others. The objective was therefore to observe whether they could drink more and more frequently, without damaging their health.

Finally, the researchers found that drinking at least six coffees a day increases the risk of developing cardiovascular disease by 22%. And this, with or without the mutation. An excess of caffeine would indeed cause high blood pressure, a precursor to these cardiac diseases. "Most people agree that if you drink a lot of coffee, you can feel nervous, irritable or even nauseous," says Professor Elina Hyppönen. This is because caffeine helps your body work faster and harder, but it is also likely to suggest that you may have reached your limit. »

According to the World Health Organization (WHO), cardiovascular disease is the leading cause of death in the world. And yet they would be one of the most avoidable. Three billion cups of coffee are consumed every day around the world, the University estimates. "It is imperative to know the limits of what is good for you and what is not. As with many things, it's all about moderation," she concludes.
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Thinking about a cup of coffee boosts the brain

What if we could enjoy the stimulating benefits of coffee without drinking it? Researchers at the University of Toronto suggest that imagining this drink is enough to feel its effects.

Notice to coffee addicts who do not plan a morning of work without a triple espresso: the simple thought of coffee would have a stimulating effect on the brain.

Sam Maglio, Associate Professor in the Department of Management at the University of Toronto in Canada, focused on the psychological impact of the simple evocation of coffee. His findings in the journal Consciousness and cognition should surprise coffee addicts: just thinking about coffee is enough to make you more alert, attentive and stimulated.

"We wanted to know if there was a link between coffee and stimulation, so that if we simply exposed people to coffee-related signals, their physiological excitement increased, as it happens if they actually drank coffee," explains Sam Maglio on the university website.

Sam Maglio, an expert in consumer behaviour, has found that exposure to coffee through indirect means does influence brain stimulation. The researcher found this effect by using four separate studies and comparing participants from Western and Eastern cultures with signals related to coffee and tea. As a result, participants exposed to elements referring to coffee had a different notion of time than the tea-exposed group: they perceived time as being shorter and thought in more concrete and precise terms. The association between stimulation and coffee, on the other hand, was less obvious among participants from Eastern cultures, where coffee is a less popular beverage.

The mental power of a food, a vast object of study

The Canadian intends to further investigate the impact of the mental perception of a food on behaviour. These upcoming studies will focus on consumer attitudes towards energy drinks or red wine, for example. It will also be important to know whether the simple fact of thinking about energy drinks, for example, could have different effects on excitement.

Drinking coffee to extend your life expectancy?

American scientists conducted an observational study to investigate possible correlations between coffee consumption and life expectancy. It would appear that drinking coffee, even up to 8 cups a day, is associated with lower mortality.

The latest recommendations were not to exceed 4 cups of coffee per day. Beyond this figure, the negative effects of this stimulant would appear. A new study by researchers at the National Cancer Institute (NCI), however, questions this figure. Indeed, drinking coffee, up to 8 cups a day, would be associated with a lower risk of death. The details of their study were published in the journal JAMA International Medicine.

Scientists analyzed data from nearly 500,000 people, aged on average 57 years, who participated in the British Biobank study. This study gathered health information on more than 9 million people. Respondents were asked how many cups of coffee they drank per day (even if it was decaffeinated), their general health, their education, and their smoking and alcohol consumption habits. DNA samples from the volunteers were also collected.

Effects even without caffeine!

These people were followed for 10 years, during which 14,000 participants died (out of 500,000). The main causes were cancer, cardiovascular and respiratory diseases. The researchers found that the more coffee the person drank, the lower the risk of death during the study period. These results are valid whether it is ground coffee, instant coffee or decaffeinated coffee. "These results suggest that the many other coffee compounds, besides caffeine, may be responsible," Erikka Loftfield, lead author of the study, told Live Science.

In addition, when researchers examined the genetic data of the participants, they identified four genes known to be associated with caffeine metabolism, i.e. how the body assimilates caffeine. Some previous studies had suggested that people with these gene variations may be at higher risk of cardiovascular disease. But in this new study, scientists found no link between these variations and a person's risk of death during the study period.

A correlation and not a causality

The researchers point out that the study only found an association with coffee and longevity, but did not prove that coffee leads to a longer life. "Although these results may reassure coffee drinkers, they come from an observational study and should be interpreted with caution," said Erikka Loftfield. This does not mean that coffee consumption should be increased. Indeed, only 10,000 of the 500,000 participants drank at least 8 cups of coffee a day, and the risk of death compared to those who consumed only 4 cups was only slightly higher. In summary, this study provides additional evidence that coffee consumption can be part of a healthy diet. Only, of course, if you don't overdo it with cream and sugar!

Coffee, friend or enemy of athletes?

Sports scientists have found that the performance benefits of caffeine are most evident among athletes who do not drink caffeine-rich beverages regularly.

Coffee would serve the performance of runners used to consuming caffeinated drinks, according to the results of a study published in the medical journal Human Kinetics Journals. On the other hand, it would be a good incentive for athletes who do not drink it regularly.

Researchers at the University of Dublin in Ireland examined the impact of caffeine, in the form of chewing gum, on the performance of 18 male athletes in a series of repeated sprints. Athletes undertook 10 races in conditions with and without caffeinated gum sticks, which is equivalent to two cups of strong coffee.

Reduce coffee consumption to improve its effects

The scientists found that caffeine-containing gum provided very few benefits to athletes who were used to drinking coffee regularly. Indeed, athletes who drank 3 cups of coffee a day saw their performance decrease.

In contrast, athletes with low caffeine intake maintained their performance after ingesting caffeine-containing gum.

"Caffeine is considered to be the friend of sports to improve performance, muscle strength, mental alertness, and reduced perception of effort during intense activity, helping athletes work faster and longer," explains Dr Brendan Egan of Dublin University.

Athletes who regularly drink caffeine should reduce their intake if they want to benefit from its beneficial effects before a competition.
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