"I can not start the day without my morning coffee." "It helps me to concentrate." "Since I read that coffee contains antioxidants, I do not hesitate to drink" ... Knowing that every second is consumed some 255 kilos of coffee around the world, it is essential to ask ourselves the question: is the favorite black nectar good or bad for health, and what is the truth in our beliefs about its supposed virtues?
Coffee: a Norman drink?
Fun drink, addictive, friendly: the coffee is consumed in the morning, afternoon, afternoon, the same evening for some. It is so popular that many scientists have looked at its effects on health. Balance sheet.
Effects of coffee on the heart and health: "It depends," say scientists
It is no longer a secret for anyone, caffeine acts as a stimulant on the body, increasing the heart rate. That said, for many years, studies have followed one another to demonstrate both the positive effects of caffeine on the heart and the negative effects. Today, it appears that the positive or harmful effects of coffee vary from one individual to another.
In the first place, everything depends on consumption. Coffee being a stimulant, do not abuse it. In addition, the health status of coffee drinkers must be taken into account to determine the effect: coffee can increase the risk of cardiovascular events if it is over consumed, but especially if the person who consumes coffee is smoker, overweight, suffers from cholesterol or hypertension, all risk factors.
Coffee and risk factors for the heart: a question of genetics
Several scientists say that caffeine can not be directly linked to heart attacks, even though the drink would have the effect of alerting the markers of inflammation of the heart, because no cohort has actually been organized taking into account all the environmental data of the individuals observed.
Finally, one of the last major studies on the subject comes from Canadian researchers at the University of Toronto. Prof. Ahmed El-Sohemy of Toronto's Department of Nutritional Sciences is parvens to demonstrate that we are not all equal when it comes to caffeine, because of our individual genetic heritage (19).
In fact, researchers have studied several thousand subjects, with the aim of observing how coffee is transformed in our body thanks to a specific enzyme.
This enzyme can take two forms depending on the genetic profile of each and have two effects: quickly degrade the coffee in the body or on the contrary, promote a slow degradation. For example, people who eliminate coffee quickly have a 22% risk of infarction for drinkers of two to three cups a day, while for people who break down the drink too slowly, the risk of heart attack is increased. by 1.35%.
Coffee: an addiction explained by genetics
Several researchers and scientists in the United States looked in 2011 at the link that could exist between caffeine consumption and perceived need. By studying the DNA of more than 40,000 people, they would have succeeded in identifying two genetic sequences at the origin of the coffee, sodas and chocolate needs of individuals. Thus, some people feel a strong need to consume coffee, sodas, tea or chocolate, and others do not, depending on their genetic profile.
Coffee, by increasing the heart rate, can be a problem if you have arrhythmia or other heart problems. We are not equal when it comes to coffee, it all depends on our DNA and our state of health.
Avoid energy drinks: up to 500 mg of caffeine
"Nutritional advice is tricky to give, because many things - like coffee - can be bad for some health conditions and individuals, but good for others consumed in moderation," says Prof. El-Sohemy. However, he is particularly cautious about energy drinks: "The high levels of caffeine in these products, which also tend to be very high in sugar, have absolutely no health benefits."
Marketing promoting these beverages is increasingly directed towards young people. According to Ahmed El-Sohemy, "the manufacturers of these energy drinks are pushing the limits in terms of caffeine concentration. Some have up to 500 milligrams per can. In comparison, a typical cola can contains 34 mg and a large cup of coffee 80 to 100 mg.
Coffee, brain and vigilance
When you consume coffee, you actually consume caffeine. This caffeine passes into the bloodstream and then crosses the "blood-brain" barrier until it binds to receptors acting on several groups of neurons, receptors normally loaded with adenosine, whose role is notably to regulate the cycles. watch and sleep, also acting on vigilance.
Coffee to concentrate
Caffeine is found in coffee of course, but also in chocolate or soda. The consumption of caffeine thus allows to remain in a state of vigilance longer, while delaying the feelings of fatigue. The coffee drinkers explain that they have the impression of "thinking more quickly" after drinking a coffee, to be more concentrated.
However, if coffee is the favorite drink of students who review at the last minute in the night their exams, caffeine does not help a better memory. On sensitive people, or following too much coffee, caffeine can make you more sensitive to stress, more aggressive and nervous.
Over consumption of caffeine can also result in tremors. Caffeine also has the effect of reducing the intensity of migraines and could even optimize the effects of an aspirin in case of headache.
Coffee composition
Coffee contains caffeine of course, but also phenolic acids (antioxidant), potassium, magnesium, phosphorus ... Taken without sugar, coffee is low in calories (about 2 calories per cup), which does not mean that it must be consumed without restriction.
Coffee and cancer: some benefits
Coffee may have protective effects against some cancers. In any case, this is what several studies show.
Coffee and colon cancer
For many years it was thought that high coffee consumption could prevent the risk of colon cancer. Yet recent studies claim the opposite. Several researchers have conducted studies on a larger number of subjects and concluded that coffee consumption would not affect this type of cancer.
Coffee and breast cancer
One of the recent studies published in the journal Breast Cancer Research would have found a beneficial effect of coffee on the prevention of breast cancer. For example, after questioning more than 6,000 post-menopausal women about their coffee consumption, the Karolinska Institute reportedly concluded that drinking more than five cups of coffee a day could reduce the risk of developing aggressive breast cancer (3). ).
These results were confirmed in a second German study. But the scientific community remains skeptical about these results, asking for studies on more women.
Coffee and skin cancer
By studying a group of mice, American researchers have succeeded in demonstrating the protective effects of coffee on the skin (4).
Thus, researchers at the University of Washington explain that after decreasing the amount of ATR in the skin of mice, a protein responsible for the multiplication of skin cells damaged by the sun, and have exposed ultraviolet rodents the latter developed tumors later than the control group without treatment.
The caffeine would have the effect of inhibiting ATR protein. The study lasted several weeks, and it appeared that the group of mice whose DNA had been modified to develop less ATR had much fewer skin tumors (-69% compared to the control group). as well as 4 times less aggressive cancers of the skin. Caffeine could therefore have a protective effect against ultraviolet rays.
Rich in antioxidants, coffee could also have protective effects on liver cancer.
Coffee, cholesterol, Parkinson's disease, and diabetes
What about the relationship between coffee, cholesterol, diabetes or Parkinson's disease? Once again, studies are numerous and sometimes hopeful.
Coffee consumption: hope for Parkinson's patients
Parkinson's disease is a degenerative disease that causes limb stiffness and slow movement, loss of balance, difficulty in movement and tremors. At the origin of the disease, a lack of dopamine, a chemical responsible for controlling movement.
However, coffee increases the production of dopamine and thus reduce the risk of developing Parkinson's disease in men. In any case, this is demonstrated by several studies particularly studied by the scientific community.
However, while some believe in the relationship coffee / risk of development of Parkinson's disease in men, studies do not allow to make the same observation with the female population.
Coffee and cholesterol
Cholesterol sufferers are often advised to slow down or limit their coffee consumption because of the very composition of coffee, which contains cafestol.
But cafestol is a molecule that has the effect of raising the level of bad cholesterol in the blood. But studies on the subject have shown that the negative effects of coffee on cholesterol would be effective in those who consume a lot of coffee.
A black coffee to fight diabetes
For more than ten years, researchers have studied the habits of nearly 70,000 French women who did not have diabetes.
All 41 to 72 years old at the time of the start of the study, finally 1,415 of them developed diabetes during the 11 years of the study. The researchers then observed the drinks they drank, tea, coffee, latte, chicory, and observed that women who regularly drank a cup of black coffee after the meal suffered less from diabetes.
This result could be explained by the presence of chlorogenic acids in coffee beans, acids that would reduce the glycemic load of a meal, hence the effectiveness of a black coffee after lunch, often the heaviest .
Another explanation puts forward the role of an antioxidant substance called lignan, assuming that antioxidants in general would have an antidiabetic effect.
Children and pregnant women: beware of coffee!
Some populations are more sensitive to food, to substances that are ingested. Women in general, and pregnant in particular, must be particularly vigilant. And, of course, children.
Women and caffeine
Two studies have reported a positive association between coffee consumption in women and stroke (stroke). For example, the AHA (American Association of Cardiology) has published a recent study by the Karolinska Institute in Sweden that shows that women who drink a cup of coffee on a daily basis would have the risk of stroke decreasing by almost 25% (20). But the mechanisms of this effect are not yet known.
Another study of 83,000 women aged 55 and over also reportedly linked regular coffee consumption with a lower risk of stroke.
Pregnant women: limiting the intake of coffee
When a woman is pregnant, many instructions are given about her lifestyle and diet. Several alarmist studies have reportedly linked too much coffee consumption to an increased risk of miscarriage or stillbirth.
Other research shows that too much coffee consumption could have a negative impact on the heart rate of the fetus, which would become too fast or irregular. Finally, it is recommended to limit caffeine intake (caffeine is present in coffee, tea, chocolate, soda) to avoid any risk.
If coffee is a real pleasure for you, you have the right to drink a cup of coffee, the idea being not to multiply. Especially since coffee can sometimes cause bloating and nausea!
Caffeine and children: beware of overdose
We do not always realize it, but between sodas, chocolate, tea, coffee ... Caffeine is much more present in our daily lives than we think. As a result, even though children generally do not like coffee because of its strong and bitter taste, they regularly consume caffeine, and often more than reason.
As a result, it is not uncommon, according to a study published in the Journal of Pediatrics, that in the United States, the dose of caffeine ingested by children is much greater than the maximum recommended daily dose. is 45 mg / day before 7 years, and 85 mg / day before 12 years.
Beyond this, children may show signs of hyper-excitation and sleep disorders that will hinder their development. In addition, it is known that caffeine can have the effect of increasing blood pressure and cause an irregular heartbeat, which is not good for the man, let alone for the child.
In the most fragile, excessive consumption of caffeine can result in constant nervousness, irritability and problems of concentration if the over consumption is irregular and the child can not readjust his sleep-wake rhythm.
In addition, caffeine is criticized for causing calcium loss through urine. This loss would be inconsequential for adults if they regularly consume calcium-rich products, but this can be more of a problem for children who are growing up.
In the end: coffee, is it good or not for health?
Like a lot of things, coffee is a drink to drink in moderation. If doctors agree that a glass of red wine a day is good for the heart, it does not mean that you have to drink the whole bottle, the same for coffee!
Many studies reveal every year new benefits to coffee, as well as new drawbacks to the drink, the idea is that you should not consume too much.
You enjoy a morning coffee to wake up and a coffee after lunch, to help you digest and get started in the second half of the day: no problem. But you do not have to drink two liters of this black drink because you love it.
For sensitive people such as children and pregnant women, extra vigilance is needed. Ladies who are expecting a child, limit yourself to one or two cups a day. For parents, watch your children's diet, caffeine is also hidden in chocolate and soda.
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