What Is Caffeine? Sources, Uses, Benefits & Side Effects 

Nikhil Goswami

Caffeinated drinks have long been the go-to drug to wake up your senses and keep you alert for longer. Consequently, most people have, at different times in their lives, consumed caffeine. It’s so widespread that three of the world’s most popular drinks coffee, tea and cola contain it. 

Though most consume caffeine regularly, not everyone knows much about it. As simple of a substance as it seems, caffeine sends complex signals to our brains, causing it to affect our behavior and thinking.

Billions of people consume this stimulant every day. Many count on caffeine for a much-needed energy boost, whether as a morning pick-me-up or to get a buzz to go through a dull afternoon. 

Also, caffeine often gets a bad rap concerning its adverse effects like increased anxiety symptoms and trouble sleeping. However, there are many upsides to this stimulant as well. It makes you energetic and active, you can find the best espresso machines on the web.

This article answers the question, “What is caffeine?” We go in-depth on how it works in the body and whether or not we should consume it. Additionally, we cover some of the many health benefits and possible side effects of caffeine. 

We also explore caffeine-rich foods and drinks. Lastly, we discuss the recommended dosages of caffeine. 

What is Caffeine?

One of the most widely popular naturally-occurring stimulants in the world is caffeine. This bitter chemical substance naturally occurs in foods such as kola nuts, cacao, tea leaves and coffee. You can find it in these plants’ fruits, seeds or leaves. It also occurs in nearly 70 other plant species. 

This substance affects the body’s central nervous system when ingested. It can increase the production of some chemicals in the brain. These chemical processes it triggers in the body are responsible for the psychological effects it has on people. 

Companies are now also producing synthetic caffeine. This man-made version of caffeine raises many health concerns, just like natural caffeine. 

People have long used caffeine for recreational purposes as far back as centuries ago.   There are many claims that it increases mental alertness as well as other cognitive benefits, but many of its purported effects are unsubstantiated by scientific research.   

Too much caffeine can be a health risk and lead to severe problems. Since the line between a safe and unsafe dose is very thin, health professionals advise that caffeine consumers take caffeine infrequently and moderately. For this reason, it’s not legal in the US to purchase concentrated caffeine in large quantities. 

More than half the world’s population consumes some level of caffeine daily. The figures are way higher in North America, where over 90% of its adult population consumes the stimulant daily. 

Besides its use in creating soft drinks and chocolates, caffeine is also a popular ingredient in energy drinks and some dietary supplements. It’s also often an ingredient of pain relievers. The FDA also approves the consumption of caffeine alongside pain relievers to relieve migraine headaches. 

How Caffeine Works 

As we stated earlier, caffeine is a Central Nervous System (CNS) stimulant. It majorly stimulates the brain, as well as the heart and muscles. 

The brain has several receptors, each with different functions. When caffeine enters the body system, it targets two crucial receptors in the brain, the A1 and A2A receptors.

A chemical neurotransmitter in the brain called adenosine is responsible for tiredness and trouble sleeping. This chemical builds up from the start of the day, and its levels increase throughout the day. Physical and mental activity are the major causes of increased production of adenosine. 

This adenosine usually binds with the A1 and A2A receptors in the brain, promoting muscle relaxation and tiredness. Caffeine intercepts these chemicals and blocks their chances of locking on to the adenosine receptors.

After taking a caffeine-rich food or beverage, your small intestine absorbs the caffeine in less than an hour. Afterward, it makes its way to the bloodstream and other parts of the body, like the brain. 

When it gets to the brain, it begins to block the adenosine from binding with the two adenosine receptors. After two hours of ingesting the caffeine, its concentration in your blood reaches its peak. At this point, caffeine binds to the adenosine receptors and prevents the adenosine from binding, thus preventing the feeling of drowsiness. This “blocking” of adenosine receptors is what allows you to feel alert and wakeful after taking a cup of caffeinated beverage.

Besides inhibiting the A1 receptor’s adenosine binding, caffeine also inhibits the A2A receptor.   This often leads to the increase in the production of certain mood-enhancing neurotransmitters in the brain. This might cause an increase in the production of dopamine, Norepinephrine and glutamate.

There is no exact understanding of how caffeine affects the Central Nervous System.   However, it’s apparent that it is psychoactive and may help boost your memory and focus. 

Foods and Drinks Containing Caffeine

Caffeine naturally occurs as a part of certain plants like cacao and kola nut.   There are dozens of plants whose leaves, fruits, or seeds contain a high caffeine content.

However, these naturally occurring caffeine sources are not the only sources of caffeine today. The caffeine found in these plants is processed and used to make caffeinated foods or caffeine pills. 

These caffeinated foods differ in their caffeine content. For example, a serving of espresso can contain up to 7 times more caffeine than the same serving of cocoa beverage. Note that some energy drink brands display false caffeine and sugar content on the labels.

Here are some beverages and their average caffeine content per 8-ounce serving. 

  • Cocoa beverage: 3 – 7mg of caffeine
  • Soft drinks: 15 – 40 mg of caffeine
  • Tea: 30 – 120 mg of caffeine
  • Energy drinks: 45 – 120 mg of caffeine
  • Yerba: 60 – 130 mg of caffeine
  • Coffee: 100 – 200 mg of caffeine
  • Espresso: 200 – 730 mg of caffeine
  • Green tea: 30 – 38 mg of caffeine

However, some beverages, like energy drinks, might have misleading labels regarding how much caffeine they contain. Therefore, drinking caffeinated beverages like some energy drinks with alcohol might not be wise. Besides caffeinated beverages, caffeine is also common in several over-the-counter medications like pain relievers. 

Some Health Benefits of Caffeine 

There are several reasons caffeine remains widely popular and consumed. There are several popular myths about caffeine, and it has recently gotten some bad press for its adverse effects. 

However, there are many benefits of taking caffeine. Many of the purported benefits are not backed with strong scientific evidence. Here are a couple of possible benefits of taking caffeine.

Fat Burning and Increased Metabolism 

There have been many reasons to believe that caffeine can change our body’s metabolic substrate. It transforms glycogen in the body into fat. This process increases lipolysis, and the hormone-sensitive lipase gets stimulated. 

High caffeine intake, e.g. taking energy drinks or other caffeinated beverages, gets Kinase A working. Kinase A is a key enzyme in glucose and lipid metabolism. 

In simpler terms, caffeine can increase our metabolism because it tends to stimulate the central nervous system. It can increase our body’s metabolism by over 10 percent and aid our body’s fat-burning capabilities by up to 13%. 

On a more practical note, a 300 mg-a-day consumption of caffeine can help you burn over 79 calories daily. Researchers carried out a decade-long study on caffeine. The study revealed that participants who drank the most coffee lost some weight after the study was over. 

Their average weight loss was about 0.95 pounds. While this may be considered negligible, it matches up to the 2.2 pounds yearly average weight gain in the US. 

You subtly raise your metabolic rate for about three hours when you drink one or more cups of coffee during your morning commute. Within these hours, your body can produce more heat to burn some fat. 

Due to its metabolism-boosting benefit, caffeine is sometimes added to over-the-counter medicines like pain relievers. The reason for this is that it is capable of speeding up the action of ingredients such as paracetamol or even ibuprofen. 

It Boosts Exercise Performance 

One benefit caffeine has is that it can increase both endurance and stamina. This partly explains its prominence in the athletic world. Dozens of research carried out have proven that caffeine enhances muscle strength. 

And this can be seen mostly in the upper part of our bodies. While there was more than enough evidence when it was studied in men, there are still more studies to be carried out to determine its impact on women. 

As an athlete, caffeine will assist in boosting the intensity of your training. It can also afford you the stamina to train longer than you usually would. Runners, cyclists and other sportsmen will receive the most benefit from caffeine. 

Caffeine boosts your exercise performance by enabling glucose resident in the muscles to last long. It also prospectively delays the normal time it would have taken the muscles to get exhausted. 

Moreso, caffeine is known to aid muscle contraction and reduce susceptibility to fatigue. 

According to studies carried out, doses of about 2.3 mg of caffeine per pound of body weight have been observed to boost endurance performance by almost five percent. This effect is best felt when caffeine is consumed an hour before you exercise. 

In addition, it can decrease all perceived exertions when exercising, thus, making your workout seem easier. 

As a psychoactive drug, it is rated among the prominently known performance-boosting drugs in the sporting world. As long as you consume the ideal dose, it will have beneficial effects. 

Protection Against Diabetes and Heart Issues 

While there are so many myths about caffeine and the heart, it’s unlikely that caffeine increases the chances of having heart disease. 

Some findings reveal that people who drink between 1 to 4 cups of coffee each day have an up to 18% lower risk of heart disease. 

A study published by the American Heart Association Journal revealed that drinking a cup of plain caffeinated coffee might decrease the risk of heart failure. 

Note that coffee assists in enhancing the control of blood pressure and blood flow carried out by the blood vessels. 

Coffee consumers might have up to a 29% lower risk of having Type-2 diabetes. 

And even with decaffeinated coffee, you have about a 20% lower risk of getting diagnosed with diabetes. It simply shows that some beneficial compounds within caffeine protect against this disease. 

Aside from heart issues and diabetes, taking two to three cups of coffee daily might help protect against specific diseases such as Parkinson’s disease and even liver cancer.

Enhance Mood and Brain Function 

Many people drink caffeine regularly to start their day due to the burst of energy it gives. As we stated, after caffeine is digested and gets to the brain, it prevents adenosine from binding with the adenosine receptors. 

This action might lead to a higher release of pleasure hormones like dopamine. This release can help enhance mood greatly in individuals. 

Consuming the right quantity of caffeine is key, however. More caffeine in your bloodstream does not necessarily mean more mood-enhancing effects. 

Some studies show that caffeine ingestion might help keep depression at bay. Other studies showed that taking 2.5 cups of coffee daily significantly lowers the risk of suicide. Another study shows that while it may decrease suicide ideation in women, it may not significantly impact male suicide ideation. 

Because caffeine helps with alertness and focus, it seems to also help in better cognitive performance. A recent study showed that caffeine positively affected performance in certain tasks like information processing and vigilance. 

Other Health Benefits of Caffeine

Besides the positive effects of caffeine on mood and brain function and other benefits, caffeine also has several other benefits. 

  • Longevity: Caffeine promotes longevity due to its potential benefit in disease prevention. Caffeine can also reduce the occurrence of premature death by up to 30%. This proves especially true for persons with diabetes and women. 
  • Liver protection: Caffeine might have a great role in reducing the chances of liver damage. Studies show that caffeine consumption can reduce the chances by over 80%.

Caffeine consumption might help decelerate the disease’s progression in people already diagnosed with liver damage. It might also cause patients to respond better to treatment and thus reduces the chances of death. 

  • Skin health: Caffeine has some antioxidant properties that might make it beneficial to skin health. It can help to protect your skin from the actions of free radicals. 

Caffeine has become popular in the beauty world for reducing the appearance of wrinkles and cellulite. Also, taking up to 4 cups of coffee daily can reduce your skin cancer risk by20%. 

  • Reduced risk of cancer: There is evidence that links caffeine consumption to lower cancer risks. The incidence of liver cancer can reduce by more than 60% when a person consumes 3 to 4 cups of coffee daily. The risk of colorectal cancer also decreases significantly. 
  • Gut health: Sufficient amounts of caffeine daily can benefit gut health. Taking 3 cups of coffee might cause a rise in the number of gut bacteria. 
  • Reduced risk of multiple sclerosis: The studies on caffeine’s effect on Multiple Sclerosis are mixed. However, one study showed that caffeine intake could significantly reduce the risk of multiple sclerosis. 
  • Gout prevention: Caffeine consumption seems to have tremendous benefits in women. For women consuming 4 – 5 cups of coffee daily, the chances of developing gout reduce by nearly 70%.

Caffeine intake has links to lower uric acid production in the body. These lower levels often stall the incidence of gout development in many people. 

Safety and Adverse Effects of Caffeine

The use of caffeine has always raised several safety concerns. However, the drug is considered safe when taken in moderation. On average, the FDA considers 400 mg of caffeine daily intake safe. 

However, there might still have unpleasant side effects of caffeine. One of the more common side effects of caffeine is tremors, also known as the jitters. Excess caffeine has both short-term and long-term adverse effects. 

In the short term, consuming too much caffeine might cause jitters. This happens because excess caffeine in the bloodstream usually amps up adrenaline availability in the body. When the body cannot use up the adrenaline, it may result in tremors.

In the long term, too much caffeine can result in cardiovascular problems, as well as digestive issues. Some short-term side effects of caffeine consumption include:

  • Trouble sleeping
  • Irregular heartbeat 
  • Stomach upset
  • Anxiety
  • Restlessness 
  • High blood pressure 
  • Headaches 

Caffeine intake can also cause dependency in users. At that point, it takes more caffeine to feel any effects. Genetics does have a role to play in caffeine tolerance and dependence. Discontinuing caffeine intake may result in unpleasant withdrawal symptoms like nausea and headaches.

Although there are safe limits for pregnant people, caffeine appears to have the ability to cross the placenta. Thus, to avoid any issues, pregnant people should stay off caffeine. Taking more than recommended doses can lead to low birth weight or pregnancy loss.

It’s also essential to note that caffeine might interact with certain drugs. It seems to interact with some muscle relaxant drugs and some antidepressants. Thus, it’s best to speak with a doctor if you have to take some medication while consuming caffeine. Mixing caffeine with alcohol, recreational drugs, or prescription medication can lead to fatal injuries. 

Recommended Dosage of Caffeine

How much caffeine is safe for you to take is essential to note. As we stated earlier, a daily caffeine intake of 400mg is generally safe for most healthy adults. This should exclude pregnant women or people on other medicines like antidepressants. Too much caffeine can lead to short-lived high blood pressure.

This 400 mg of caffeine a day threshold is approved by the European Food Safety Authority and the United States Department of Agriculture. This threshold equals about 4 cups of coffee or ten cans of soda. However, taking this daily caffeine dosage in one sitting is not recommended. 

Instead, it’s best to spread that dosage into a few cups of caffeinated beverage. Some studies show that a second cup of caffeinated coffee consumed immediately after the first did not offer any extra benefits. However, if it were taken hours later, it would have an increased effect on mood. 

For pregnant women, it’s best to keep your daily dosage at 200 mg of caffeine or less or avoid caffeine completely. The same goes for people trying to get pregnant women and breastfeeding mothers. Caffeine consumption in a breastfeeding woman will also cause an increase in breast milk caffeine levels.

As for powdered caffeine, the FDA advises against consuming it. This is because the caffeine in powder or liquid forms usually contains unsafe levels of caffeine. A tablespoon of powdery caffeine is equivalent to nearly 50 cups of coffee. 

Children should steer clear completely of caffeine as it may harm their health. Young adults, on the other hand, can consume coffee within safe limits. 

Conclusion: Is Caffeine For You?

Caffeine is a popular stimulant with many health benefits. It’s the go-to substance to stay sharp and focused all day. Caffeine stimulates different parts of the Central Nervous System, and the health effects of caffeine are enormous.

  Nevertheless, we now use it in modern society as a mild stimulant. We discussed how caffeine in the body works, from its intake to its effects on the brain, in this article.   

The mild psychoactive effects of caffeine are what make it the stimulant of choice for everyday use. Caffeine is well received by most healthy adults. It’s also considered when taken in moderation. More caffeine doesn’t always equal more benefits.

Although several studies exist on the effect of caffeine on our health, several studies are still underway. Some mechanisms of caffeine are not completely understood yet. However, for now, caffeine seems to have some positive impact on a user’s health. 

Some studies show that it may be able to increase metabolic rate and aid fat burning. It may also help guard against diseases like diabetes and some forms of cancer. Caffeine also has benefits for skin health. 

With all these established, there are still safety precautions to observe while consuming caffeine. It also can have severe interactions with several drugs. All in all, it’s best to discuss with a physician about your caffeine consumption and drug interactions.


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