Because boiling will bring some aromatic substances to gather on the surface of coffee, thus forming foam, and the aroma of coffee depends on the density of foam. If coffee is boiled after boiling, it will destroy the foam and make the aromatic substances lose with the steam.

Avoid drinking too much coffee: after drinking high-concentration coffee, the adrenaline in the body suddenly increases, which leads to the acceleration of heart rate, obvious increase of blood pressure, and abnormal phenomena such as tension, anxiety, tinnitus and involuntary trembling of limbs. In the long run, it will affect health.

Don't put too much sugar in coffee: if you put too much sugar, people will be listless and even feel tired after drinking it. This is because drinking coffee with too much sugar will reflexively stimulate islet cells in the pancreas and secrete a lot of insulin, and excessive insulin will reduce the glucose content in the blood. Once the blood sugar is too low, there will be symptoms of hypoglycemia such as palpitation, dizziness, weakness of limbs and lethargy.

In addition, when drinking coffee, don't eat too many high-sugar foods such as cakes and sweets, otherwise the above phenomenon will also occur.