How many cups of coffee should you drink every day?

Coffee is an indispensable drink for Westerners in life, whether it is waking up in the morning to awaken the sleeping soul, refreshing at work or the leisure of afternoon tea.

Caffeine "is a natural ingredient found in the leaves, seeds or flesh of more than 60 plants, such as coffee beans, cocoa beans, cola beans and tea, while the most common food sources are coffee, tea, chocolate and cool drinks (such as cola, tea-containing drinks). Caffeine has a mild central nervous stimulation and can reduce fatigue, enhance memory, reasoning and intellectual flexibility. As long as a small amount of 32 milligrams (about 1 cup of cola) can improve auditory and visual reaction time, but everyone's sensitivity to caffeine varies greatly, and some people think that increasing the amount of flexible caffeine may make some people feel uncomfortable, and the elderly may be more sensitive to the effects of caffeine.

There seems to be a constant debate about whether coffee brings more health benefits or more harm. How much coffee should I drink every day?

1 cup of coffee

The upside: Greek researchers studied 485 people over the age of 65 and found that one cup of coffee a day can keep arteries healthy and stabilize blood pressure. A survey of 600 volunteers at the University of Bristow in the UK also showed that one cup of coffee a day can boost brainpower.

The downside: it takes eight hours for caffeine to be fully excreted, so if you drink coffee after 3 or 4 p.m., it's easy to have sleep disorders.

2 cups of coffee

Benefits: a study by the University of Florida found that 200 milligrams of caffeine, equivalent to two cups of coffee, can prevent memory loss and Alzheimer's disease. Research in the International Journal of Sports Medicine also shows that drinking coffee 30 minutes before exercise can help improve performance.

The downside: if you are pregnant, you should consume less than two cups of coffee, otherwise it will increase the risk of miscarriage.

3 cups coffee

Benefits: a study published in the American Journal of Chemical Medicine found that three cups of coffee a day reduced women's risk of ovarian cancer by one percent. Men who drank three drinks a day had a 40% lower risk of gallstones.

The downside: a 2006 study in the United States showed that three cups of coffee a day increased heart rate and blood pressure slightly, which may increase the risk of heart attack.

4 cups coffee

The upside: a study by the University of Utah found that four cups of coffee contained about 400 milligrams of caffeine, which reduced the risk of oral and throat cancer by 39 percent. In addition, it can reduce the risk of colon cancer, breast cancer and type 2 diabetes.

The downside: four cups of coffee a day doubles the risk of rheumatoid arthritis.

More than 5 cups

The upside: a 10-year study of 90,000 people by researchers in Tokyo found that five cups of coffee a day reduced the risk of liver damage by three to four.

The downside: caffeine interferes with calcium absorption and increases the risk of osteoporosis. Drinking too much will accelerate the loss of minerals and vitamins in the body. While increasing high blood pressure, it also increases the risk of cardiovascular disease.

Even if there are many reasons why you love coffee, make it a good partner for a healthy life first. Therefore, experts warn that for most people, the total daily intake of caffeine had better not exceed 250 mg, which is equivalent to drinking 3 cups of coffee.

And a new study from Cornell University found that drinking one cup of coffee a day can reduce the risk of retinal degeneration caused by aging, diabetes and glaucoma, GlobalNews reported.

In the new study, Professor Li and his colleagues at Cornell University often exposed the eyes of some experimental mice to nitric oxide gas, which causes oxidative pressure and free radicals, and exposure to the gas is more likely to lead to retinal degeneration. The results of the comparative study showed that compared with the experimental mice that were not pretreated with antioxidant chlorogenic acid (CLA), the experimental mice treated with this technique did not develop retinal degeneration even after exposure to nitric oxide.

Professor Li pointed out that raw coffee contains about 9% chlorogenic acid, a highly effective phenolic natural antioxidant that can effectively prevent retinal degeneration. The retina is the most active metabolic tissue in the body. it is a thin layer of tissue composed of many photosensitive and nerve cells in the posterior wall of the eyeball. Lack of oxygen and the production of free radicals in the body can cause retinal damage.

Professor Li said that in animal experiments, the amount of CLA used in animal experiments is equivalent to that of humans drinking 1 cup of coffee a day, indicating that drinking coffee regularly can effectively reduce the risk of retinal damage. At the same time, drinking coffee can also help prevent vision degradation and the risk of blindness caused by various causes.

A new study by the Korean Academy of Science and Technology published in the American Journal of Agricultural and Food Chemistry also found that drinking three or more cups of coffee a day can reduce the risk of type 2 diabetes by more than 37%. Previously, the study found that drinking four cups of coffee a day reduced the risk of liver cancer by 42 percent. Another study found that drinking two or more cups of coffee a day reduced the risk of liver cirrhosis by 66%. Drinking coffee also helps prevent Parkinson's disease and liver disease.