Coffee (and caffeine) has been used for thousands of years. It is the world's most popular psychostimulant. Caffeine is found not only in coffee beans, but also as a natural ingredient in tea leaves and cacao beans. It is also found in many products of the food and pharmaceutical industries such as sodas (cola) and in pain-killers (e.g.:Anacin®).
Caffeine's chemical composition identifies it as part of the methylxanthine family. These products stimulate the production of certain substances at brain level, which results in a stimulation of the central nervous, cardiac, pulmonary and digestive systems and, in an increase of the basic metabolic rate.
In order to evaluate your daily consumption, here is a list of products that contain caffeine:
5 ounces of decaffeinated coffee: 2-5 mg
5 ounces of percolated coffee: 60-125 mg
5 ounces of instant coffee: 40-105 mg
2 ounces of espresso: 100 mg
5 ounces of hot chocolate: 2-10 mg
5 ounces of milk chocolate: 5-75 mg
5 ounces of tea infused for 5 minutes (strong): 70-110 mg
5 ounces of tea infused for 3 minutes (weak): 20-50 mg
5 ounces of herbal tea: 24-130 mg
12 ounces of cola: 45 mg
12 ounces of iced tea: 70 mg
1 chocolate bar: 30 mg
Pain medication: 15-32 mg
1 Wake-up pill: 100 mg
The main effect of caffeine is that it stimulates the central nervous system. This increases our vigilance and helps up stay awake. Consequently,caffeine can cause insomnia and anxiety. Approximately 100 mg of caffeine (strong coffee) may hinder sleep, mostly in people who do not normally consume caffeine or in people who suffer from recurrent insomnia.
Pregnant women should consume caffeine moderately; a maximum of 200mg/day is recommended. As of yet, we do not know all the effects caffeine may have on the foetus. However, it is thought that excess consumption can lead to a delayed growth of the foetus and cause low birth weight. We know that the rate of elimination of caffeine through the kidneys is reduced during the second and third trimesters, which increases the intensity and duration of its effects. However, no congenital malformations are associated to caffeine consumption. Women who breastfeed must also consume caffeine moderately, as it flows freely in maternal milk; the baby only absorbs small quantities but he/she may be sensitive to small doses of caffeine.
As with other drugs, there is a risk of becoming addicted to caffeine. Withdrawal symptoms may appear in a person who suddenly stop consuming caffeine after having consumed large quantities and/or after having consumed it for long periods of time. The main symptoms are headaches, sleepiness, irritability, tensed-up muscles, problems concentrating and nervousness. These symptoms disappear over the course of a week, more or less.
Athletes sometimes use caffeine to increase their performance. It is a stimulant, much as amphetamines, ephedrine or cocaine. The effects sought are: increase in vigilance, heartbeat and respiratory rate acceleration, increase in aggressiveness, decrease in fatigue caused by effort and increase in glycemia and the use of lipids as energetic substrate. The ingestion of massive doses of caffeine, such as seen in some athletes, may lead to over-training. In such a case, the body does not recognize alarm and fatigue signals and this may cause injuries and physical exhaustion. Caffeine is tolerated in sports competitions, as long as it remains at an acceptable level, i.e.: the equivalent of a few coffees or soft drinks. Standards vary according to the sports associations.
If you have any questions related to your caffeine consumption, consult your pharmacist.