Caffeine is a substance belonging to the family of alkaloids, a group of compounds widespread in plants.

Caffeine, like other alkaloids (atropine, nicotine, strychnine, morphine, etc.) is physiologically active on animals even at very low concentrations and is probably used by the plant as a defense mechanism against herbivores.

Caffeine also affects many biological reactions in humans. Some of these interactions are beneficial for the body while others are responsible for the side effects of this substance.

Caffeine (mainly extracted from coffee, Coffea arabica, family Rubiaceae ), belongs to the group of purine alkaloids such as theophylline (from tea, Camellia sinensis, fam. Theaceae ), and theobromine (from cocoa, Theobroma, family Sterculiaceae ).

Caffeine is not only contained in coffee but is also found in other plants and foods. This is the case, for example, of coca cola, mate herb, chocolate, Cola-based energy drinks, herbal products such as guarana, not to mention analgesics, anti-cellulite cosmetics or drugs for diseases from cooling. It is curious to note, for example, how tea leaves have about twice the caffeine content (2-4%) compared to coffee seeds (1-2%); however, due to the different method of extraction, the infusion contains approximately four times less caffeine than percolate.

Caffeine in Foods

DrinksContained in caffeine
COFFEE'85 mg (a cup).
COKE35-40 mg (one can)
THE28 mg / 150 ml (the greater the longer the infusion is)
COCOA100 mg / 100 g
RED BULL30 mg / 100 ml
PLEASE NOTE: in athletes it is necessary to take into account the summative effect of caffeine taken with the various foods so as not to exceed the limits imposed by the anti-doping regulations. The caffeine content of traditional mocha coffee is higher than in espresso In women, the use of some contraceptives (ethinyl estradiol) increases the duration of action of caffeine by about 50%.
INTESTINAL ABSORPTION TIME: about 45 minutes. EMIVITY: 2.5- 4.5 hours.

Effects of caffeine

Caffeine is the most used psychoactive drug in the world, its chemical conformation makes it suitable to interact with specific biological receptors that regulate the functionality of the cardiovascular, endocrine and nervous systems.

The intestinal tract absorbs caffeine very quickly and the plasma concentration peaks are observed about an hour after its ingestion. However, its metabolism is rapid and decidedly superior compared to other stimulants such as amphetamines. Plasma caffeine levels are reduced by 50% as early as 3-6 hours after intake.

Being lipophilic, caffeine has the ability to rapidly pass the blood-brain barrier (a kind of virtual wall present in the brain, designed to prevent the passage of many molecules carried by the blood).

Caffeine also manages to cross the placenta and may be present in breast milk. It is therefore advisable to greatly reduce the intake of coffee and other caffeinated foods during pregnancy and breastfeeding.

Although the effects of this substance are very numerous (as we will see in detail in a few lines) most of them are due to the stimulating effects that caffeine exerts on the whole organism.

NERVOUS SYSTEM:

excitability, improvement of reflexes and ability to concentrate, analgesic action,

ACTION MEDIATED BY INTERACTION WITH BIOLOGICAL RECEPTORS (cardiovascular and respiratory system):

Thanks to its competitive antagonist action against adenosine receptors, caffeine promotes the release of two hormones called adrenaline and noradrenaline.

Catecholamines promote an increase in body metabolism, heart rate, blood pressure and the number of breaths (thus increasing blood oxygenation)

ADDITIONAL FUNCTIONS:

increased acid synthesis at gastric level, increased diuresis;

if applied to the skin through specific cosmetics (creams, gels and patches), it is useful in the treatment of localized fat deposits.

Caffeine, sport and doping

If taken within the maximum permitted levels, caffeine has a positive effect on the performance of most athletes. Even moderate all-in-one doses (200-400 mg) ingested an hour before the competition improve attention, concentration and endurance. Given the great individual variability, it is advisable to experiment with its use in training before taking it in the race.

An athlete tests positive for anti-doping tests when the concentration of caffeine in his urine exceeds 0.012 mg / ml (= 12 mcg / ml). It is not easy to determine exactly what the intake dose can overcome this threshold. It is generally recommended not to take more than 6-8 cups of espresso or two or three cups of traditional coffee in the three hours before the competition.

Caffeine and weight loss

Due to their high caffeine content, tea and coffee are often recommended to promote weight loss (in combination with a correct diet). Several studies have confirmed this property, which finds a logical explanation in its stimulatory effect on basal metabolism. In particular, 500 mg of caffeine (the equivalent of 5 or 6 coffees) increase the basal metabolism by 10-15%. Translated into simpler and more immediate terms, a similar level of intake makes it possible to consume 100-500 extra calories a day (in relation to body size and above all to the subject's muscle mass).

Caffeine is a characteristic ingredient of cosmetics to treat cellulite and localized fat deposits; applied to the skin it promotes the mobilization of triglycerides from subcutaneous adipose tissue mediated by lipolytic lipase.

OTHER USEFUL INFORMATION: chewing 1-2 coffee beans helps purify the breath after a large meal. Coffee does not promote digestion, on the contrary, if taken with a lot of sugar or worse still with cream or alcohol, it slows it down. However, the stimulant effects of caffeine can give the sensation of apparently better digestion.

Negative effects of caffeine

Coffee reduces the absorption and bioavailability of some substances:

riboflavin or vitamin B2

calcium (reduce consumption in the presence of osteoporosis and bone fractures)

iron

creatine

A caffeine intoxication caused by the massive intake of this substance (over 500-1000 mg in relation to individual sensitivity) causes excessive excitement, nervousness, insomnia and tachycardia

Caffeine should therefore be taken in moderation in the event of:

esophagitis and gastroesophageal reflux (in addition to increasing the damaging power of gastric juices, caffeine relaxes the esophageal sphincter, a kind of valve that prevents the gastric contents from rising back up into the esophagus)

stomach ulcer

anemia

hypertension

tachycardia, arrhythmias and heart problems in general

osteoporosis

Prolonged use of caffeine tends to dampen the beneficial effects seen previously and, if taken at high doses, accentuates the side effects (acidosis, pulmonary edema, hallucinations).

Several studies have described the presence of a mild withdrawal syndrome.