Caffeine is a substance found in coffee, tea or chocolate and also some medicine components which stimulates the central nervous system, giving the effects as following:

• Awake. Caffeine in coffee can stimulate the central nervous system in the brain, giving you a clear thinking and refresh your brain.
• Antioxidants. Caffeic acid and chlorogenic acid in coffee have antioxidant functions, which can eliminate free radicals and slow the aging process of the human body.
• Diuretics. Caffeine causes kidneys produce more urine to remove toxins out of the body. Coffee, black coffee in particular, has significant diuretic effect and can be helpful in eliminating edema.
• Preventing diabetes. Caffeine has the ability to increase blood sugar levels, but only for a short time and it increases the sensitivity of insulin in the body, prevents the development of type 2 diabetes.
• Weight loss. Coffee can boost metabolism and reduce heat, so it can achieve effective weight loss.
• Antidepressants. Coffee can make everyone happy and full of spirit, and also reduce depression.

How Long Does Caffeine Last in the Body?

Caffeine is metabolized within the liver by the enzyme system called cytochrome P450 oxidase into three separate physical effects on the body; known as paraxanthine, theobromine and theophylline. Caffeine from coffee or other beverages is absorbed by our digestive system about 45 minutes after drinking, and then distributedto all tissues in the body. The half-life of caffeine, which refers to the time needed to eliminate half amount of caffeine out of the body, depends on many other factors such as age, body condition, liver function, etc.

• In healthy adults, the half-life of caffeine is 4.9 hours.
• In pregnant women, the half- life is 9-11 hours.
• In infants as well as young kids, the half-life of caffeine is longer than the adults, about 30 hours.
• Patients with severe liver disease, caffeine may accumulate in the liver with the half-life up to about 96 hours.

What Is the Recommended Daily Amount of Caffeine?

The results of some research scientists at the University of Tokyo (Japan) showed that drinking a coffee daily (about 100-150 ml of diluted coffee) can help prevent the risk of asthma, decrease 25% of colon cancers, 45% of gallstone disease, 80% of cirrhosis and nearly 90% of Parkinson's disease. Some people tend to be sensitive to caffeine than others. Those who don’t regularly drink coffee are more susceptible to negative effects of caffeine. There are some studies showed that men prone to the effects of caffeine more than women, especially those special subjects.

• Healthy adults. For most healthy adults, the moderate dosage of caffeine is approximately 200 to 300mg being equivalent to about 2-4 cups of coffee a day which is not entirely harmful to health.
• Pregnant women. If the 1^st-trimester pregnant women (pregnancy in the first 3 months) drink coffee, the dosage of 150 – 300mg daily or more (2-3 cups per day) would be harmful to the fetus, leading to fetal defects, especially congenital malformations of the limbs.
• Teenagers. Children should not drink coffee, teens can drink milk-coffee (milk with a bit of coffee only) approximately less than 100mg caffeine daily.

If you are susceptible to the possible effects of caffeine, just a small amount - a cup or even a sip of coffee or tea - can make you feel excitable, jittery or even insomnia.

What Will Happen if Taking Too Much Caffeine?

If drinking 4 or more than 4 cups of coffee a day can lead to some unpleasant effects because using more than 500 to 600 mg of caffeine a day can cause.

• Addictive feeling. Skip coffee on those who drink coffee regularly can cause some symptoms such as insomnia, headaches, fatigue, concentration difficulty and depression.
• Osteoporosis. Caffeine will cause loss of calcium leading to osteoporosis. Thus, the women regularly drink coffee should pay attention to calcium supplementation.
• Risk of myocardial infarction. Caffeine causes an imbalance in blood sugar (hypoglycemia), weak heartbeat, easy to sweat, stress and heart attacks. Especially if women drink regularly large amounts of coffee, it would increase the risk of myocardial infarction.
• Stomach pain. Coffee will promote increased gastric secretion and gastric acid. So, drinking too much coffee will lead to discomfort in the stomach.
• Abnormal fetal. Coffee can cause abnormalities of the fetus, so pregnant women should not drink too much of coffee daily.
• Hard to conceive. Caffeine in coffee will affect your chances of getting pregnant.
• Tachycardia.If you want to cut down caffeine, it should be reduced the quantity of coffee slowly. Otherwise, it can cause headache, malaise, fatigue and stress. Fortunately, these symptoms are usually mild and able to go away after a few days.

Cautions for Caffeine Intake

Above are the benefits and disadvantages of coffee on human health. It is important to take control of coffee consumption daily. Do not drink too much; otherwise it will be harmful to your body. Here are some cautions for caffeine intake.

• Start paying attention to how much caffeine you are getting from food and beverages. Beware of the food and beverages that can contain caffeine.
• Cut down gradually. For example, drinking a cup of coffee or tea per day only. Avoid caffeinated beverages at the late moments of the day.
• Drinking tea immediately after done to shorten the incubation time (time for tea to infuse), so as the caffeine in tea can’t be extracted much. Or just choose herbal tea which has no caffeine.
• Choose non-caffeinated coffee (decaf coffee).
• Inspect the medication before using. Some pain relief drugs contain 130 mg caffeine in only one dose. Look for pain relief without caffeine instead.