1. How much coffee can a healthy adult drink every day?

According to the recommendations of American Food and Drug Administration, European Food Safety Agency, Health Canada, ANZ Food Standards Bureau and other authoritative organizations, the maximum daily intake of caffeine for a healthy adult is 400 mg. Take Starbucks as an example, the caffeine content of Chinese and American (355ml) is about 150mg, so generally speaking, it is no problem to drink two cups of Chinese and American every day.

2. When is the best time to drink coffee to refresh yourself?

When "adenosine" and "adenosine receptor" in the body combine, the brain will receive fatigue signals, and then we will feel sleepy. The principle of coffee refreshing is that caffeine can replace adenosine and adenosine receptor. When caffeine occupies all adenosine receptors, the brain basically does not receive fatigue signals. So, if you want to refresh yourself, I suggest drinking coffee before you feel sleepy. Drinking when you are sleepy is basically ineffective.

3. How long does drinking coffee before going to bed not affect sleep?

First of all, we should know that the half-life of caffeine (that is, the time required for the human body to convert half of caffeine intake) is generally 3-6 hours. Take the half-life of 6 hours as an example: after ingesting 10/50mg of caffeine in the morning, the caffeine content is about 25mg at night, which is lower than that of a can of cola (the caffeine content of a can of cola is about 30-40mg), and basically does not affect sleep.

4. Why don't some people drink coffee to refresh themselves?

Drinking coffee has no refreshing effect, which may be due to the following reasons. Individual differences: Some people are born with strong ability to metabolize caffeine, or are born with insensitivity to caffeine. Tolerance to caffeine: Drinking coffee regularly will enhance the tolerance to caffeine. Drinking coffee is already very sleepy: if you want to refresh yourself, it is recommended to drink coffee before you feel sleepy.

5. Can minors drink coffee?

Generally speaking, minors at the stage of physical development are advised to drink less or not to drink coffee.

6. Can pregnant women and lactating women drink coffee?

Caffeine ingested by pregnant women and lactating women may be absorbed by the fetus/baby, which may affect the growth and development. It is recommended to drink less or no coffee. At the same time, due to the slow metabolism of caffeine in pregnant women and newborns, it is suggested that even drinking coffee must be controlled.

7. What kind of people are not suitable for drinking coffee?

Long-term insomnia: coffee has a refreshing effect. For people who have long-term insomnia, it is necessary to drink as little coffee as possible. Caffeine intolerance: Some people are born with low tolerance to caffeine, and it is easy to have a rapid heartbeat and anxiety after drinking a cup. For such people, we also suggest to drink as little coffee as possible.

Osteoporosis: Medical research shows that drinking a certain amount of coffee may hinder the absorption of calcium, so osteoporosis patients or the elderly suggest drinking less coffee and supplementing more calcium. Pregnant women and lactating women: Like pregnant women and lactating women, caffeine intake may be absorbed by the fetus/baby, thus affecting growth and development, so it is necessary to control the amount of coffee.

8. Will your teeth turn yellow after drinking coffee for a long time?

This is because coffee contains a dark brown substance-tannic acid. When tannic acid stays on the teeth for a long time, it will slowly penetrate into the teeth and cause tooth coloring. But as long as you pay a little attention when drinking coffee, you can effectively avoid staining your teeth. Try not to sip coffee for a long time. The longer coffee is in contact with teeth, the easier it is to dye. If the temperature permits, you can use a straw to reduce the contact between coffee and teeth.

Chewing gum can stimulate saliva secretion and neutralize coffee tannin. After drinking coffee, rinse your mouth as much as possible, and then brush your teeth (don't brush your teeth first, because the acidic substances in coffee are corrosive to your teeth, and brushing your teeth will easily cause tooth wear at this time).

9. Will drinking coffee for a long time make your skin black?

Coffee will not affect whitening, on the contrary, caffeine has a powerful skin care effect. Protect skin: Caffeine has antioxidant effect, which can scavenge free radicals, protect skin from ultraviolet rays, improve dull skin and fine lines, and delay aging. Calm the skin: Caffeine has high antioxidant activity, which can relieve the symptoms of skin inflammation and redness. Eliminate edema: Caffeine can help remove excess moisture from skin and make skin firm and delicate. Activate skin: Caffeine can promote metabolism, stimulate cell vitality and make skin full of vitality.

10. Can you really lose weight by drinking coffee?

Black coffee itself can't lose weight, but it helps to lose weight. Black coffee is a very low-calorie beverage: 100ml coffee liquid has only 3 or 4 calories (1 calorie = 1000 calories). Caffeine is a great help to lose weight: caffeine can stimulate gastrointestinal peristalsis, accelerate the metabolism of the body (which can increase the metabolic rate by 3%), promote digestion, promote diuresis and defecation, help relieve constipation, and promote the burning and decomposition of body fat.