Seven facts about caffeine, seven things you don't know about caffeine.

Coffee is a common drink. However, as an important ingredient in coffee, how much do you know about caffeine? The American magazine Women's Health recently published "7 things you don't know about caffeine."

1. Caffeine is good for both short-term and long-term memory. Earlier studies have found that caffeine is good for short-term memory, while recent studies have found that caffeine is also good for long-term memory. Dr. Jack Lynn London, senior dietitian at Mount Sinai Hospital in New York, said eating 300 to 400 milligrams of caffeine a day can help prevent cognitive decline and Alzheimer's disease.

two。 Caffeine can improve sports performance. Drinking coffee an hour before the game can improve the performance of the game. The reason is that caffeine can increase alertness and shorten reaction time.

3. Caffeine is refreshing and has an immediate effect. Caffeine can easily cross the blood-brain barrier and quickly stimulate the central nervous system. You will feel refreshed immediately after taking caffeine, and your euphoria will peak after 30 to 60 minutes.

4. The content of caffeine in coffee varies greatly. A study published in the Journal of Analytical Toxicology found that 16 ounces of coffee from a famous brand contained 100 milligrams more caffeine than the same amount of other caffeine. Research also shows that even the same brand of coffee, each bottle of caffeine content also varies, up to 300 milligrams. Dr London said a 16-ounce cup of standard coffee contained caffeine ranging from 90mg to 225 mg.

5. Espresso contains much less caffeine than regular coffee. Everyone thinks that espresso must have the most caffeine. However, a cup of espresso contains only 40 to 70 milligrams of caffeine, much less than the same amount of regular coffee, Dr. London said. Therefore, if you are sensitive to caffeine, it is best to choose espresso such as cappuccino.

6. Caffeine does not cause dehydration. According to the U.S. Food and Drug Administration, 98% of caffeine is consumed through beverages, so caffeine is replenished at the same time. So although caffeine is a diuretic, it doesn't really cause dehydration. However, you should drink coffee in moderation. Drinking water is the gold standard for replenishing water.

7. Caffeine doesn't just come from drinks. Chocolate is also a major source of caffeine. Some foods and even drugs such as painkillers also contain caffeine. People with heart disease or high blood pressure should consult a professional doctor before taking caffeinated painkillers.