"Coffee is full, refreshing" "Monday American, a week is fine"...... Coffee has become a "life-sustaining artifact" for students and migrant workers, according to public data, Chinese consumers consumed a total of nearly 300,000 tons of coffee in 2022.
As more and more people choose coffee, so do the claims of coffee. Is it true that coffee causes anemia?
Coffee doesn't have to be refreshing?
01
Latte with "iron"?
Only non-heme iron is affected
Recently, a netizen said, "The physical examination report shows that the hemoglobin is only 91, I often drink coffee since I go to work, I feel tired recently, I am out of breath when I climb the fourth floor, I can't sleep enough every day, I went to the doctor and said that I am anemic and can't drink coffee and tea." ”
Does coffee really affect iron absorption and cause anemia?
The answer is: yes, but not much; Also, don't "replenish iron" while drinking it and you'll be fine.
Because after the polyphenols, caffeine, phytic acid and other plant components in coffee enter the human body, they will combine with iron, rob the position of iron ions, reduce the absorption rate of iron, and thus affect the absorption of non-heme iron.
It is important to note that it is non-heme iron that is affected! That is, the iron in cereals and vegetables in our daily food. The absorption rate of non-heme iron is very low, and it is difficult to be absorbed and utilized by the body.
The "iron" required by the human body mainly depends on heme iron, and coffee has no effect on heme iron in meat (beef and mutton, fish and poultry).
In addition, the effect on iron absorption is also related to when you drink it. If you're consuming iron, drinking coffee may block some iron absorption, but it won't drain your body from iron. Studies have found that drinking coffee an hour before meals has no effect on iron absorption.
In general, if you can ensure that you get enough iron in your usual diet, such as eating more lean meat, eating fruits and vegetables separately from coffee (vitamin C in fruits and vegetables can promote iron absorption), coffee will not be "latte".
02
"Immunity" to coffee?
It's also true that you fall asleep after drinking
Coffee, some people drink a cup and can't sleep all night, and some people drink two or three cups a day and get sleepy, what is the reason behind this? Is there really such a thing as "immunity"?
Starting from the mechanism of the brain, first of all, it is adenosine and adenosine receptors that are responsible for the production of sleepiness in our brain. Secondly, caffeine is a stimulant of the central nervous system, which mainly relies on it for a refreshing effect. The molecular structure of caffeine is similar to adenosine, and its appearance blocks the adenosine molecule responsible for slowing down the central nervous system before bedtime, and binds to the adenosine receptor first, so it naturally cannot produce sleepiness normally.
图源：foodrepublic
Through this mechanism, caffeine "hijacks" the brain, blocks the transmission of sleepiness signals, and improves alertness and cognition.
Caffeine can also increase the heart's beating rate, raise blood pressure, and even affect our mood. That's why some people feel anxious or excited after drinking coffee.
But why do some people who drink coffee often have coffee that "doesn't work", and even have a certain "sleep aid" effect? It is because if you consume caffeine for a long time, caffeine always preempts the receptor of adenosine, which is a neurotransmitter involved in energy metabolism and consumption.
If this is already the case, you need to take a break down and rest a little bit until the adenosine in your body is broken down and your brain can rekindle your love for caffeine.
Remember, coffee only delays the arrival of exhaustion, but it does not eliminate it.
In addition, everyone's response to caffeine is different, which may be mainly due to the efficiency of enzymes in the liver that are involved in caffeine metabolism, and genes, age, weight, and even sex can all affect how we respond to caffeine. Moreover, caffeine is not only found in coffee, such as energy drinks, tea, milk tea, and cola.
03
How to drink coffee effectively and healthily?
Find the right time and strike first
In recent years, researchers around the world have confirmed that coffee has multiple meaningful health benefits. Drinking coffee may reduce the risk of colorectal and liver cancer, as well as reduce the risk of cardiovascular disease......
Some people know that there are many benefits of drinking coffee, but they are also afraid that they will get flustered after drinking coffee. How do you drink it right? How to drink without these adverse reactions?
1 "Latte" worries about the family, stagger the meal and drink
For people with iron deficiency anemia, it is recommended not to drink coffee at the same time as a meal, and it is recommended to drink it 1 hour after a meal; If you drink coffee, you can eat more lean meat, eat more fresh fruits and vegetables, and you can also take iron and vitamin C supplements to ensure that you can consume enough iron.
2. Look at the half-life and find the best time
Depending on the individual's metabolism, caffeine is actually quickly absorbed in the gastrointestinal tract and metabolized in the liver, so normal coffee intake generally does not cause insomnia.
If you are a person who suffers from insomnia after drinking coffee, you can start with the half-life of coffee, which is a concept in atomic physics that refers to the time it takes for half of the nuclei of radioactive elements to decay.
By analogy, the metabolic process of caffeine in the body also proceeds according to the first-order kinetic process, and there is also a relatively stable half-life, which is specifically defined as the time it takes for its concentration in the body to drop by half.
The half-life of caffeine is about 3 to 5 hours (take 4 hours on average), in simple terms, the concentration of caffeine in the body is halved after about 4 hours, and it is reduced to a quarter after 8 hours, so people who are sensitive to caffeine should not drink coffee within 4-8 hours before bedtime.
Or you can choose decaffeinated or decaf coffee. Note! Decaf coffee exists, but not completely absent, it's just that caffeine is very low, very low, maybe only 10% of the caffeine of 1 cup of regular coffee, or even less.
3. If you want to use coffee to refresh yourself, you have to start first
It takes time for coffee to go from intake to absorption. Generally, it takes about 45 minutes after drinking coffee to be fully absorbed by the body, and 99% of the caffeine will start to work. If you feel sleepy at 3 p.m., you have to start drinking it around 2:15 p.m., and when it reaches its peak, the pick-me-up effect will get worse and worse as the half-life develops, which is why the more you work after drinking coffee, the more sleepy you become.
In addition, it is also a good way to refresh yourself after drinking coffee and sleeping for a while before working. According to a new study in the United Kingdom, drinking a cup of coffee before napping can make you feel better when you wake up. This is because short periods of sleep help the brain remove the drowsiness-producing adenosine, a pattern that researchers call a coffee nap, claiming that drinking a cup of coffee before naptime can increase the effects of caffeine on the brain and improve memory.
Finally, we need to drink it correctly and in moderation, don't rely on coffee, and take a proper rest after a busy day. In general, it is safe to drink up to 3-4 cups (about 400 mg of caffeine) of coffee per day.
P.s. Also pay attention to the sugar and cream content of coffee, too much sugar and cream can increase calorie intake.
The next time you have a cup of coffee in your hand, not only do you know how to enjoy it scientifically,
If you also know the scientific principles, you may have a different experience!
Source: Guangdong Science Popularization, Science China, Institute of Physics, Chinese Academy of Sciences, International Medical Department of Zhongshan Hospital Affiliated to Fudan University Editor: Wen Jialin Cheng Huanying Editor: Chen Guangtai
How many cups of coffee do you drink a day?