Caffeine: Uses, addiction and side effects.


Caffeine is used by billions of individuals every day to help them get up, get through a night shift, or get over an afternoon slump. This natural stimulant is, in fact, one of the most widely utilized chemicals on the planet. It is well-known for its detrimental effects on sleep and anxiety. According to studies, it does, however, appear to provide a number of health benefits. The latest research on caffeine and your health is examined in this article.

What is caffeine?

It is a natural stimulant that can be found in a variety of foods, including coffee, tea, cola, cocoa, guarana, yerba mate, and more than 60 other products. It works by activating the brain and central nervous system, which keeps you awake and prevents fatigue. Historians trace the origins of brewed tea to 2737 B.C. Many years later, an Ethiopian shepherd is said to have found coffee after noticing how much more vitality it gave his goats. Caffeinated soft drinks and energy drinks first appeared on the market in the late 1800s. Caffeinated products are consumed by 80 percent of the world’s population every day, and this ratio rises to 90 percent for adults in North America.


How caffeine works

Caffeine is readily absorbed into the bloodstream after consumption. It then travels to the liver, where it is broken down into chemicals that can alter organ function. It’s main effect, however, is on the brain. It works by inhibiting the effects of adenosine, a neurotransmitter that relaxes the brain and causes tiredness.

Adenosine levels normally rise throughout the day, making you feel fatigued and driving you to want to sleep. It keeps you awake by binding to and activating adenosine receptors in the brain. This reduces sleepiness by blocking the effects of adenosine. It may also raise blood adrenaline levels and boost dopamine and norepinephrine neurotransmitter activity in the brain.

This combination increases brain stimulation and enhances arousal, alertness, and focus. It is commonly referred to as a psychoactive substance because of its effects on the brain. Caffeine has a short half-life. For example, the amount present in one cup of coffee can reach the bloodstream in as little as 20 minutes and take up to an hour to attain maximum impact.

Caffeine-containing foods and beverages

Caffeine can be found in the seeds, nuts, and leaves of a variety of plants. Caffeinated foods and beverages are made from these natural sources, which are harvested and processed. The caffeine content per 8-ounce (240-mL) serving of various popular beverages is as follows:

  • Espresso: 240–720 mg
  • Coffee: 102–200 mg
  • Yerba mate: 65–130 mg
  • Energy drinks: 50–160 mg
  • Brewed tea: 40–120 mg
  • Soft drinks: 20–40 mg.
  • Decaffeinated coffee: 3–12 mg
  • Cocoa beverage: 2–7 mg
  • Chocolate milk: 2–7 mg

Caffeine is also found in some foods. 1 ounce (28 grams) of milk chocolate has 1–15 mg, while 1 ounce (28 grams) of dark chocolate contains 5–35 mg. It is also found in certain prescription and over-the-counter treatments such as cold, allergy, and pain relievers. It’s also used in a lot of weight-loss supplements.

May improve mood and brain function.

Caffeine has the ability to block the chemical adenosine, which is involved in brain signaling. Other signaling chemicals like dopamine and norepinephrine are increased as a result of this. This shift in brain messaging is thought to improve your mood and cognitive abilities. Participants showed better alertness, short-term recollection, and response time after ingesting 37.5–450 mg of it, according to one study.


Furthermore, drinking 2–3 cups of caffeinated coffee per day (containing roughly 200–300 mg) was connected to a 45 percent lower risk of suicide in a research. Another study found that caffeine drinkers have a 13 percent lower risk of depression. More of it isn’t always better when it comes to your mood. According to a study, a second cup of coffee has no additional benefits until it is consumed at least 8 hours after the first cup.

Drinking 3–5 cups of coffee or more than 3 cups of tea every day will lower your risk of brain illnesses like Alzheimer’s and Parkinson’s by 28–60 percent. It’s worth noting that, in addition to caffeine, coffee and tea also include additional bioactive substances that may be useful.

May boost metabolism and fat burning.

Caffeine’s capacity to activate the central nervous system has been shown to boost metabolism by up to 11% and fat burning by up to 13%. In practice, taking 300 mg of it per day can help you burn an extra 79 calories per day. This quantity may appear insignificant, yet it is comparable to the calorie surplus that accounts for the average annual weight increase of 2.2 pounds (1 kg) in Americans. A 12-year study on caffeine and weight gain found that those who drank the most coffee were just 0.8–1.1 pounds (0.4–0.5 kg) lighter at the end.

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May enhance exercise performance.

Caffeine may boost the use of fat as a source of energy during exercise. This is advantageous because it extends the life of glucose stored in muscles, potentially delaying the time it takes your muscles to exhaustion. It may also help with muscular contractions and fatigue tolerance. According to the researchers, when taken 1 hour before exercise, doses of 2.3 mg per pound (5 mg per kg) of body weight increased endurance performance by up to 5%.


Benefits may be obtained with doses as low as 1.4 mg per pound (3 mg per kg) of body weight. Furthermore, studies show that team sports, high-intensity workouts, and resistance exercises all have similar benefits. Finally, it has been shown to lessen perceived intensity during exercise by up to 5.6 percent, making exercises seem less difficult.

May protect against heart disease and diabetes.

Caffeine, contrary to popular belief, does not increase the risk of heart disease. In reality, studies suggest that men and women who drink 1–4 cups of coffee each day (equivalent to 100–400 mg of caffeine) have a 16–18% lower risk of heart disease. Other studies demonstrate that drinking 2–4 cups of coffee or green tea each day reduces the risk of stroke by 14–20%.

Caffeine can significantly boost blood pressure in some people, so keep that in mind. However, this effect is usually minor (3–4 mmHg) and fades over time for most people who drink coffee on a daily basis. It may also help prevent diabetes. According to a study, people who consume the most coffee have a 29 percent decreased risk of type 2 diabetes. Those who eat the most caffeine, on the other hand, have a 30 percent decreased risk.

For every 200 mg of caffeine consumed, the risk lowers by 12–14 percent, according to the authors. Decaffeinated coffee consumption was also associated to a 21 percent lower incidence of diabetes. This suggests that coffee’s other beneficial ingredients may also help to prevent type 2 diabetes.

Other health benefits of coffee:

Coffee consumption has been linked to a number of other health benefits, including:

  • protection of the liver. Coffee has been shown to lower the risk of liver damage (cirrhosis) by up to 84 percent. It has the potential to halt disease progression, increase therapy response, and reduce the risk of mortality.
  • Longevity. Coffee consumption may reduce the risk of early death by up to 30%, especially in women and those with diabetes.
  • Cancer risk is reduced. Drinking 2–4 cups of coffee each day can lower the risk of liver cancer by up to 64% and of colorectal cancer by up to 38%.
  • Protection for the skin. A daily intake of four or more cups of caffeinated coffee may reduce the risk of skin cancer by 20%.
  • Lower MS risk. Coffee drinkers may be 30 percent less likely to acquire multiple sclerosis (MS). However, not all investigations have come to the same conclusion.
  • Gout prevention. Gout risk is reduced by 40% in males and 57 percent in women who drink four cups of coffee each day on a regular basis.
  • Gut health is important. In as little as three weeks, drinking three cups of coffee a day can boost the amount and activity of good gut bacteria.

Coffee also provides other nutrients that are beneficial to your health. Some of the following advantages could be attributed to substances other than caffeine.

Side effects and safety

Caffeine usage is generally regarded as harmless, though it can become addictive. Anxiety, restlessness, tremors, irregular pulse, and difficulty sleeping are some of the negative effects connected to excessive consumption. For some people, too much coffee can cause headaches, migraines, and high blood pressure.

Caffeine can also easily penetrate the placenta, increasing the risk of miscarriage or having a low birth weight baby. Pregnant women should keep their intake to a minimum. It has the potential to interact with some drugs and should be avoided by anyone taking the muscle relaxant Zanaflex or the antidepressant Luvox, as these medicines can intensify their effects.


Special precautions and warnings

Caffeine is possibly safe during pregnancy and breast-feeding when consumed in doses that are regularly present in foods. it’s doses of up to 300 mg per day appear to be safe. This is roughly equivalent to 3 cups of coffee. It’s possible that consuming more during pregnancy or during breast-feeding is dangerous. It may raise the risk of miscarriage and other complications during pregnancy. It can enter breast milk as well. Breast-fed infants who consume a lot of caffeine while breastfeeding may experience sleep issues, irritability, and increased bowel activity.

Children: Caffeine is possibly safe for children and teenagers when consumed at levels found in foods.

Anxiety disorders: Caffeine may aggravate these symptoms. If you have anxiety, use coffee with caution and in small doses.

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Bipolar disorder: Too much caffeine may exacerbate the disease. If you have bipolar disorder, use it with caution and in small doses.

Bleeding disorders: Caffeine has been shown to worsen bleeding conditions. It should be used with caution if you have a bleeding issue.

Heart conditions: Caffeine can cause an irregular heartbeat in people who are hypersensitive to it. It should be used with caution.

Diabetes: Caffeine may impact how the body uses sugar in diabetics. It should be used with caution if you have diabetes.


Diarrhea: Caffeine may aggravate diarrhea, especially when used in excessive amounts.

Epilepsy: Caffeine should be avoided in excessive dosages by people who have epilepsy. Low amounts should be used with caution.

Glaucoma: Caffeine causes glaucoma by raising the pressure inside the eye. After ingesting caffeinated beverages, the increase occurs within 30 minutes and lasts for at least 90 minutes.

High Blood Pressure: Caffeine use may raise blood pressure in people who already have high blood pressure. However, in people who consume it on a regular basis, this does not appear to be a serious worry.

Loss of Bladder Control: Caffeine can exacerbate bladder control problems by increasing the frequency of urination and the urge to urinate.

Irritable bowel syndrome (IBS): Caffeine, especially in excessive doses, may aggravate diarrhea in IBS sufferers.

Weak Bones (Osteoporosis): Caffeine can increase the quantity of calcium washed out in the urine, which can lead to weak bones (osteoporosis). It should be limited to less than 300 mg per day if you have osteoporosis or low bone density (approximately 2-3 cups of coffee).

Parkinson’s disease: Taking coffee with creatine may hasten the progression of Parkinson’s disease. Caffeine should be used with caution if you have Parkinson’s disease and are taking creatine.

Schizophrenia: Caffeine may exacerbate the symptoms of schizophrenia, according to a new study.


Recommended dosages

The US Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) both regard 400 mg of caffeine as safe on a daily basis. This equates to two to four cups of coffee per day. It’s worth mentioning, though, that single dosages of 500 mg of it have been recorded to cause fatal overdoses. As a result, it’s best to keep your consumption to no more than 200 mg per dose. Pregnant women should limit their daily intake to 200 mg, according to the American College of Obstetricians and Gynecologists.

Which has more caffeine: tea or coffee?

The popularity of caffeine as a natural stimulant is unrivaled. It’s present in over 60 plant species and is used in coffee, chocolate, and tea around the world. The amount of it in a drink varies based on the components and how it’s made. While it is generally regarded as safe, excessive consumption might cause problems. Below we examined the caffeine concentration of several teas and coffees to help you decide which one to consume.

Why is caffeine such a problem?

An estimated 80% of the world’s population consumes caffeinated beverages on a daily basis. Safe intake is defined by the US Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) as up to 400 mg per day, 200 mg per single dose, or 1.4 mg per pound (3 mg per kg) of body weight. It has been linked to health advantages such as greater alertness, improved athletic performance, heightened mood, and increased metabolism due to its stimulating effects. However, taking large quantities—such as single doses of more than 500 mg—can cause problems.

 Caffeine has been linked to anxiety, restlessness, and sleeping problems in large quantities. Furthermore, some studies suggest that drinking it on a regular basis, even in small doses, can result in persistent headaches and migraines. It is also somewhat addictive, and some people may be more prone to establishing a dependency than others.


The caffeine level varies depending on the type of beverage and how it is prepared.

The caffeine content in tea and coffee varies greatly depending on the drink’s origin, kind, and preparation. Tea leaves have a content of 3.5 percent, while coffee beans have a content of 1.1–2.2 percent. The coffee brewing technique, on the other hand, employs hotter water, which extracts more caffeine from the beans. In most cases, you’ll use more coffee beans than tea leaves in a cup. As a result, 1 cup (237 ml) of brewed coffee has more caffeine than 1 cup (237 ml) of tea.

Tea varieties

Tea leaves from the same plant, Camellia sinensis, are used to make black, green, and white teas. The time of harvest and the level of oxidation of the leaves are what distinguish them. Black tea leaves are oxidized, but white and green tea leaves are not. This gives black tea its distinctive bold and harsh flavor, as well as increasing the amount of caffeine infused into hot water.

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A typical cup of black tea (237 ml) contains 47 mg of caffeine, but it can have up to 90 mg. Green teas have 20–45 mg of caffeine per cup, while white teas have 6–60 mg (237 ml). Another high-caffeine tea is matcha green tea. It is normally powdered and has 35 mg of caffeine per half-teaspoon (1 gram) of consumption.

Yerba mate, a South American tea prepared from the twigs and leaves of the Ilex paraguariensis plant, typically contains 85 mg of caffeine per cup (237 ml). It’s also worth noting that, despite the fact that herbal teas are advertised as caffeine-free, one mug can contain up to 12 mg of it. Nonetheless, this is regarded as a minor sum.

Tea preparation

Tea’s caffeine content is heavily influenced by how it is prepared. Longer steeping times and hotter water yield a more robust cup of tea. After 1 minute of steeping in 6 ounces (177 ml) of water heated to 194–203°F (90–95°C), a mug of Tazo Earl Grey has 40 mg of caffeine. After 3 minutes, the amount rises to 59 mg. In comparison, after 1 minute of steeping under the identical conditions, Stash Green Tea contains 16 mg of caffeine. This more than doubles to 36 mg after 3 minutes of steeping.


Coffee varieties

The caffeine content in an average 8-ounce (237-ml) cup of coffee is 95 mg. It’s a popular misconception that dark-roasted coffee has more of it than light-roasted coffee. However, as roasting has no effect on caffeine, this may not be the case. Dark roasted coffees, on the other hand, are less dense than light roasted coffees, so you can use more beans or grounds when brewing them, providing more caffeine per cup.

Espresso contains a higher concentration of caffeine. A “single” espresso shot from Starbucks, for example, has roughly 58 mg of it per 1-ounce (30-ml) shot. Most specialty coffee drinks, such as lattes and cappuccinos, contain 116 mg of it from a double shot of espresso. Decaf espresso contains the greatest caffeine, ranging from 3–16 mg in every 16-ounce (473-ml) dose, although decaf coffee normally contains less than 3 mg in each 8-ounce (237-ml) cup. Between these two forms of coffee are decaffeinated teas.

Coffee preparation

Tea leaves absorb more caffeine from hotter water, and coffee does the same. Coffee is usually made at a higher temperature than tea, usually between 195 and 205 degrees Fahrenheit (90 and 96 degrees Celsius). Cold-brewed coffee can also be made by soaking ground coffee in cold, filtered water for 8–24 hours. This approach, which uses 1.5 times more ground coffee than standard hot-water brewing, may result in a more caffeinated cup.


Which should you drink?

Caffeine is a stimulant that works quickly, usually within 20 minutes to an hour of ingestion. If you’re sensitive to the it’s effects, stick to low-caffeine teas such as white or herbal teas. You can also make high-caffeine tea in less time, such as one minute rather than three. Decaffeinated tea, coffee, and espresso are other helpful ways to avoid too much caffeine in these beverages. If you like high-caffeine beverages, however, you may enjoy espresso, cold-brew coffee, and high-caffeine teas, including green and black types.

Drink no more than 400 mg of caffeine a day, or 200 mg at a time, to stay under safe limits. This equates to three to five 8-ounce (237-ml) cups of normal coffee or eight 1-ounce (30-ml) espresso shots each day. Caffeine should be avoided by people who have heart problems, migraines, or are taking certain drugs. Pregnant or lactating women should limit their intake to 200 mg per day. One 12-ounce (355-ml) cup of coffee or four 8-ounce (237-ml) mugs of long-brewed black tea.


Caffeine isn’t as harmful as it was once thought. In reality, evidence suggests that the opposite is true. As a result, it’s okay to think of your daily cup of coffee or tea as a fun way to stay healthy.

Caffeine can be present in a variety of foods and beverages, such as coffee, teas, chocolate, and a variety of sports and energy drinks. Each cup of coffee has 95-200 mg of it. Each cup of black tea has 25–110 mg of it. Each cup of green tea has 30-50 mg of it. Caffeine items that are highly concentrated or pure are harmful to one’s health. By accident, people might readily consume doses that are far too high. These goods should be avoided.

Caffeine has traditionally been taken by adults in amounts ranging from 50 to 260 mg per day. Consult a healthcare professional to determine the optimal product and dosage for a specific problem.

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