(PHOTO: VCG)

By ShiHI Shi & ZONG Shihan

In daily life, some people can drink as much coffee as they want, while others have a sip and then struggle to sleep.

"It is mainly due to the varying sensitivity and metabolic speed of caffeine among individuals," explained Wang Mingyu from the First Hospital of Shanxi Medical University. This difference is influenced by various factors such as genes, age, gender, and weight, with enzymes in the liver playing a significant role.

Caffeine in coffee is a central nervous system stimulant that can stimulate the cerebral cortex, enhancing alertness and attention. Some people are naturally able to metabolize caffeine faster, making them less prone to excitement or insomnia after drinking coffee. However, others require a longer time to metabolize caffeine and are more sensitive to it, leading to symptoms such as palpitations and trembling hands after drinking coffee.

For those who are naturally sensitive to caffeine but still enjoy coffee, Wang recommends taking some measures to balance this conundrum. Firstly, it is best to consume coffee in the morning or afternoon to avoid affecting sleep at night. Secondly, one can choose low-caffeine or decaffeinated coffee varieties. Additionally, pairing coffee with milk, cookies, or other food can help slow down the absorption of caffeine, reducing its stimulating effect on the central nervous system.

"Adults should not consume more than 400 milligrams of caffeine per day, which is approximately equivalent to two large cups of  Americano or five cups of instant coffee,"  said Wang. The caffeine content in different brands and types of coffee also varies, so the specific consumption amount should be adjusted according to individual circumstances.