Generally, people who don't drink at ordinary times have psychological hints, and they will get immediate results after drinking.

People who usually drink are usually of little use, just keeping a little refreshing effect.

Caffeine is a central nervous system stimulant and metabolic stimulant. Caffeine is not only used as a drink, but also as a medicine. Its function is to refresh and relieve fatigue. The exact dose of caffeine that everyone needs to have an effect is different, mainly depending on the body shape and caffeine tolerance. Caffeine can start to work in the body in less than an hour, and the effect disappears after taking moderate doses of caffeine for 3 to 4 hours. Eating caffeine can not reduce the required sleep time, but can only temporarily alleviate the feeling of drowsiness.

Because of these effects, caffeine is a functional enhancer: it improves the ability of the brain and body. A study of 1979 shows that compared with the control group, athletes who take caffeine have improved their performance in long-distance cycling events by 7%. Other studies have achieved more remarkable results: an experiment on trained runners showed that after taking 9 mg/kg caffeine, the endurance of straight running increased by 44% and that of circular running increased by 55%. Such remarkable improvement is not an isolated case, and some subsequent studies have obtained similar results. Another study shows that the duration of cycling can be increased by 29% after taking 5.5 mg of caffeine per kilogram of body weight.

Caffeine is sometimes mixed with other drugs to improve its efficacy. Caffeine can improve the curative effect of headache-relieving drugs by 40%, and make the human body absorb these drugs faster and shorten the action time. Therefore, many over-the-counter headache drugs contain caffeine. Caffeine is also combined with ergotamine to treat migraine and cluster headache, and can also overcome drowsiness caused by antihistamines.

Respiratory problems in premature infants are sometimes treated with caffeine citrate. After treatment with caffeine citrate, the bronchial dysplasia of premature infants was significantly reduced. The only drawback of this treatment is that temporary weight gain will slow down during the treatment. In many countries, caffeine citrate can only be obtained by prescription.

Caffeine is safe for humans, but it is toxic to some animals, such as dogs, horses and parrots, because the ability of these animals to decompose caffeine is much weaker than that of humans. Caffeine has a significant effect on spiders, far higher than other drugs. Caffeine can stimulate the central nervous system and muscles, so it can refresh the mind, enhance thinking ability and restore muscle fatigue. Acting on the cardiovascular system can improve heart function, relax blood vessels and promote blood circulation. For the gastrointestinal system, it can help digestion and help the decomposition of fat.

Help to lose weight

I believe many people have heard that drinking black coffee can lose weight. In fact, this is only one of the factors. Caffeine can really accelerate the decomposition of fat, but at the same time, it needs to rely on muscle movement to convert excess fatty acids into heat energy for consumption. If there is no coordinated exercise, excess fatty acids will flow back along the blood stream and accumulate fat again. Therefore, after drinking coffee, you need to exercise actively at the same time in order to have a real weight loss effect! Coffee itself has calories, but not much. The main calories are the creamer and sugar you add when you drink coffee.

antioxidation

In recent years, all foods with antioxidant function are very popular in the market. Generally, vegetables and fruits are rich in vitamins A, C and B. Tea, which is quite popular in Japan, is regarded as healthy food because it is rich in antioxidants and can resist the harm of free radicals to human body. A few days ago, a research report pointed out that the content of antioxidants in coffee is four times that of tea, and it has stronger resistance to cardiovascular diseases. Moreover, coffee itself conforms to the principle of antioxidants, with darker color and bitter taste. Each coffee contains different antioxidants because of different brewing methods. For example, American coffee contains the least antioxidants, while espresso contains the most antioxidants. After adding creamer to coffee, its antioxidant effect will not be affected.

Improve dry eye

Foreign reports point out that people who drink coffee are much less likely to suffer from dry eye than those who don't drink coffee. This is mainly related to the purine component in coffee (eye drops containing purine can stimulate glands to secrete liquid, which has a certain protective effect on eyes). This is of course good news for computer people who love to drink coffee, but it should be noted that coffee itself has diuretic effect, even if some of its ingredients have protective effect, people who have already suffered from dry eye and those who have taken any drugs containing diuretic ingredients must be forbidden to take caffeinated drinks so as not to aggravate the loss of water in their bodies.

It can relieve pain.

Headache caused by a bad night's sleep or pain caused by vasoconstriction on one side of the temple can be relieved by coffee, but it must be drunk in the morning or at noon (note: it is forbidden from afternoon to night).

The amount of coffee is good for the human body, but you should not drink too much. It is advisable to drink no more than 2 cups a day. For people who are easily nervous and anxious, drinking too much may be harmful.

coffee time

It is best to drink coffee after breakfast and lunch, because it can promote the peristalsis of the stomach, help digestion and break down the high-calorie and high-fat food you eat, and will not stimulate the stomach like drinking coffee on an empty stomach. It is best not to drink coffee after meals, for fear of affecting sleep. If you want to stay up late by drinking coffee, you may unconsciously drink too much, which is not good for your health.

When you're nervous, it makes things worse.

Caffeine helps to improve alertness, sensitivity, memory and attention. But if you drink more coffee than you are used to, you will have the same dose of stimulants, which will cause tension. For people with anxiety tendency, caffeine can aggravate the symptoms of sweating, palpitation and tinnitus.

Aggravate hypertension

Caffeine is often combined with other simple painkillers because of its analgesic effect. However, if you take a lot of caffeine for a long time, if you already have high blood pressure, using a lot of caffeine will only make your situation worse. Because caffeine alone can raise blood pressure, if combined with emotional tension, it will have a dangerous multiplier effect. Therefore, people at risk of hypertension should especially avoid drinking caffeinated drinks when working pressure is high. Some people who drink coffee all the year round think they are immune to the effects of caffeine, but this is not the case. A study shows that after drinking a cup of coffee, the blood pressure can rise for as long as 12 hours.

Induced osteoporosis

Caffeine itself has a good diuretic effect. If you drink a lot of coffee for a long time, it will easily lead to bone loss, which will adversely affect the preservation of bone mass and may increase the threat of osteoporosis in women. However, the premise is that people who usually have insufficient calcium intake in food, or people who don't exercise often, and postmenopausal women, due to insufficient estrogen, calcium loss, coupled with a large amount of caffeine, may pose a threat to bones. If you can enjoy it in a reasonable amount, you can still do it without choking.

These people drink coffee carefully.

Taking caffeine in patients with liver disease can prolong the time of caffeine in the body. It takes 2 hours for normal adults to metabolize caffeine, but it may take 4-5 hours for patients with liver disease or liver insufficiency. Therefore, patients with liver disease must be careful when drinking coffee, and it is best not to drink it after the evening, so as to avoid long metabolism time affecting sleep, and it is best not to exceed 1 cup a day.

Patients with digestive diseases believe that people who often have stomachaches and stomach problems have an experience, and doctors will definitely tell them not to eat irritating foods, including wine, peppers, coffee, tea and carbonated drinks. Coffee is one of them, because its tannic acid can stimulate gastric acid secretion. If you are a patient with acute digestive system diseases, you must avoid drinking it. After recovery, if you drink coffee occasionally, it is best to use it after meals to avoid drinking coffee on an empty stomach.

Pregnant women Many women will pay special attention to all the foods they eat after pregnancy, and caffeinated drinks are of course listed as one of the taboos. This is mainly due to the slow metabolism of caffeine in pregnant women, which will prolong the time of caffeine staying in the body, while it takes eight or nine months for the fetus in the abdomen to remove caffeine from the blood through metabolism.

Children's half-life of caffeine metabolism will be prolonged due to incomplete liver and kidney development and poor detoxification ability, so generally speaking, children below 12 need to ban caffeine intake. Even Europeans and Americans who drink coffee as boiling water all day have strict restrictions on children's drinking coffee.