Caffeine is a naturally occurring chemical stimulant called trimethylxanthine. Its chemical formula is C8H10N4O2. It is a drug, and actually shares a number of traits with more notorious drugs such as amphetamines, cocaine and heroin. In its pure form, caffeine is a white crystalline powder that tastes very bitter. It is medically useful to stimulate the heart and also serves as a mild diuretic, increasing urine production to flush fluid out of the body.
In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. It is the world's most widely consumed psychoactive drug, but, unlike many other psychoactive substances, it is both legal and unregulated in nearly all parts of the world. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, enjoy great popularity; in North America, 90% of adults consume caffeine daily.
Caffeine is toxic at sufficiently high doses, but ordinary consumption poses few known health risks, even when carried on for years — there may be a modest protective effect against some diseases, including certain types of cancer. Some people experience sleep disruption if they consume caffeine, especially during the evening hours, but others show little disturbance and the effect of caffeine on sleep is highly variable.
The amount of caffeine in a cup of coffee can vary greatly, depending on its origin or the composition of the blend, the method of brewing and the strength of the brew. Instant, or soluble, coffee generally contains less caffeine than roast and ground coffee, but may be consumed in greater volume. Robusta coffees have about twice as much caffeine as arabicas. A 'cup' is usually understood to contain 150 ml (5 oz in the United States) but an espresso may be as small as 40 ml.
The U.S. Food and Drug Administration gives the following ranges for caffeine contents:
(mg per 5 oz cup)
|
|
range |
average |
|
Roast and ground -drip method -percolator |
60-180 40-170 |
115 80 |
|
Instant coffee |
30-120 |
65 |
A survey of caffeine contents in cups of coffee was conducted in Canada (Stavric et al.). Whether the coffee was prepared by housewives at home, for sale in commercial outlets, or by individuals at work, the mean caffeine content was about 80 mg per cup (about 350 mcg per ml). The means for roast and ground coffee, both drip and percolator brewed, were below 85 mg; for instant coffee 71 mg. However, the range of measurements was so wide that, for most individuals, it would be inaccurate to use these figures as a basis for calculating the exact amount of caffeine consumed in a day. The size of the cup/serving varied from 25 ml (Greek coffee) to 330 ml at home and from 130 ml to 280 ml in the out-of-home situation.
Whatever method of decaffeination is used, the decaffeinated green coffee must contain less than 0.1% caffeine (dry weight basis) to comply with EC regulations. This corresponds to about 3 mg caffeine in a cup of decaffeinated coffee.
Caffeine withdrawal symptoms are a side effect of reducing or eliminating caffeine in the diet. Although people often speak lightly about being irritable after missing their morning coffee, some caffeine withdrawal symptoms are serious, and caffeine withdrawal has been recognized as a disorder. Learn what to expect from caffeine withdrawal (including when it occurs and which symptoms are common), as well as how to reduce caffeine withdrawal symptoms.
Whether you've decided to give up caffeine for Lent or reduce caffeine to eliminate symptoms of excess caffeine consumption, you may find that reducing or eliminating caffeine in your diet can result in a range of unpleasant caffeine withdrawal symptoms, such as headaches and irritability.
Around 50 percent of people experience caffeine withdrawal symptoms when they cut back on or eliminate caffeine, and experimental studies have shown that around 13 percent of people experience such severe symptoms (such as headaches so severe that they are temporarily unable to work).
Typically, the more caffeine you consume, the higher your chance of experiencing caffeine withdrawal symptoms, and the higher the chances of your caffeine symptoms being severe. As little as three consecutive days of caffeine consumption can be enough to cause caffeine withdrawal symptoms after caffeine consumption ends.
Caffeine withdrawal symptoms often begin around 12 to 14 hours after stopping caffeine intake. They are typically at their worst after 24 to 48 hours, and can last for up to nine days.
Caffeine withdrawal symptoms vary in type and severity from person to person. These are common caffeine withdrawal symptoms:
Chills and/or hot spells
Decreased alertness
Depressed mood
Difficulty concentrating or thinking
Digestive issues (usually constipation, but sometimes also nausea and / or vomiting)
Fatigue, lethargy and / or sleepiness
Headaches, ranging from moderate to severe, and usually starting behind the eyes before spreading
Irritability (moderate to extreme) and restlessness
Insomnia (Although it seems counterintuitive, this can be an issue for some people!)
Muscle stiffness and / or pain
Sinus issues (usually blocked sinuses or cold-like symptoms)
Although many people prefer to quit their bad habits suddenly, it is not recommended for caffeine elimination, as quitting caffeine "cold turkey" tends to worsen caffeine withdrawal symptoms substantially. Instead, try cutting back gradually. If coffee is your caffeine vice, cutting back by half a cup per day is a good approach, as is drinking a blend of regular and decaf coffee or gradually switching to decaf. If you drink tea, reduce your intake slowly, try teas with lower caffeine levels or opt for decaf teas. If you drink colas, try getting smaller sizes or slowly scaling back your daily intake.
Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Caffeine:
Dizziness; irritability; nausea; nervousness.
Seek medical attention right away if any of these SEVERE side effects occur when using Caffeine:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); diarrhea; shakiness; trouble sleeping; vomiting.
Some of the negative side effects that caffeine has, which you may not be aware of, are:
Panic attacks. Caffeine keeps us up because it triggers the fight-or-flight mechanism in our bodies. But after heavy doses of caffeine and after many hours of it being in our system, the fight-or-flight instinct gets reduced to panic attacks. Your hands become shaky, your skin sweaty, and you always expect bad things to happen to you.
Addiction. Caffeine is addictive. Once we get into the habit of getting our caffeine fix, our body begins to crave the boost that we get from it. If we fail to get the dose of caffeine that our body has adapted to, we become irritable, tired, and even depressed.
Dehydration. One would think that since coffee is liquid, it can hydrate you. Actually, the caffeine in coffee and any other foodstuffs that has it is linked with dehydration. That is mainly because of caffeine’s diuretic properties.
PMS. Women who drink a lot of coffee and eat a lot of chocolates tend to experience pre-menstrual syndrome more acutely than women who do not. The headaches, the bloated feeling and the belly cramps become keener with the added consumption of caffeine.
Emotional fatigue. Caffeine wakes up the body, but what it fails to do is to tell the body when to stop moving and simply rest. The body needs rest and when the body does not get it, it can lead not just to physical tiredness but also emotional fatigue.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects.
nervousness; headache; increased heart rate
anxiety; upset stomach; irregular heartbeat
irritability; GI irritation; elevated blood pressure
agitation; heartburn; increased cholesterol
tremors; diarrhea; nutritional deficiencies
insomnia; fatigue; poor concentration
depression; dizziness; bed wetting.