Caffeine: Benefits, Uses, Dosage, and Side Effects

The powerful stimulant to energize your brain performance.

Caffeine: Benefits, Uses, Dosage, and Side Effects

Caffeine is best known for acting as a mild stimulant to the central nervous system that quickly boosts alertness and energy levels.

It has also been associated with health benefits for treating cardiovascular problems, type 2 diabetes, regulating weight gain, stroke prevention, and improving physical activity levels.

On the flip side, there is an equal number of health concerns associated with its consumption. Common ones include headaches, jitters, and anxiety after consuming caffeine.


    What is Caffeine?

    Caffeine is a stimulant compound that affects the central nervous system.

    It contains substances that change how the brain and body work, with some beneficial effects and others that may become potentially dangerous.

    That is why this psychoactive drug is the subject of much controversy.

    How Does Caffeine Work?

    If you ask people what caffeine does for them, the foremost reasons given will be that it increases mental stimulation, alertness and makes them feel good. And there’s no denying either.

    Caffeine does provide mental stimulation and alertness, and hardly anyone will deny that their regular cup of joe is anything short of a miracle.

    And that is why so many products in the market today include caffeine. This ranges vastly from nootropics and fat burners to weight loss products and other drugs.

    When ingested, caffeine gets absorbed in the small intestine within the hour.

    From here, it enters the blood circulation, which carries it to all parts of the body, including the brain.

    Caffeine absorption is affected by food or food components in the gut, such as fibers that can impact how quickly or slowly it peaks in the blood.

    How Caffeine Affects The Brain?

    Acting as a central nervous system stimulant, the most noticeable effect is alertness when caffeine reaches the brain. This happens as it blocks adenosine receptors in the brain.

    This helps increase adenosine levels in the body and prevent drowsiness.

    It may also elevate adrenaline levels and escalate dopamine and norepinephrine activity to stimulate a state of focus and arousal.

    Once caffeine levels wear off, adenosine kicks back in, causing a reduction in neural activity and brings on drowsiness.

    What Foods And Drinks Contain Caffeine?

    Different food types yield caffeine in varying amounts:

    • Coffee delivers 150-200 milligrams of caffeine per 8 oz cup.
    • Black tea yields 60-90 mg
    • Green tea provides 30-70 mg.
    • Oolong Tea caters 50-75 mg.
    • Yerba mate is a beverage that contains about 40 mg per 8 fl oz. cup
    • Guarana can contain up to 3.65-5.8% caffeine by weight. In comparison, coffee only has up to 2%.
    • Energy drinks – If you must drink these, do so only occasionally. Taking an energy drink yields as much caffeine as three cups of coffee, and most are loaded with sugar and herbal stimulants for the extra kick.
    • Soft drinks – The amount in a 12-oz can of soda is about half of what you would get from a cup of coffee but is very high in sugar. So, like an energy drink, have these as an occasional treat.
    • Cocoa – 100 g of cocoa powder yields 230 milligrams of caffeine.
    • Cacao – The powdered form contains 49 mg per 15 g or 2.5 tablespoons, while cacao nibs have 41 mg of caffeine per 30 g or 3 tbsp.
    • Chocolate – The darker the chocolate, the higher the caffeine content with dark chocolate containing 12mg per ounce. This is followed by milk chocolate at 9mg and white chocolate at no caffeine per ounce.

    Drinking coffee and tea are more natural unsweetened caffeine sources in the diet and superior options than soda or energy drinks.

    What Are The Health Benefits of Caffeine?

    Caffeine is seen as beneficial for both the mind and body.

    Although habit-forming, it is generally considered safe when taken in moderation.

    Mood and Brain Function Improvement

    For obvious reasons, many people reach for a cup of coffee to help them stay alert.

    When classified as a nootropic, this benefit provides a short-term boost to alertness, attention, and focus.

    Research indicates that caffeine may boost more accelerated information processing by improved brain entropy (1).

    This indicates that coffee consumption may be suitable for brain health in the long run in improving memory and cognitive performance.

    In terms of mood enhancement, evidence from a small pilot study showed that caffeinated coffee consumption had a more powerful impact on mood than decaffeinated coffee, even though the decaffeinated version could also improve mood and reduce anxiety (2).

    Research also suggests that caffeine may help alleviate depressive symptoms.

    Boosts Metabolism and Fat Burning

    Drinking coffee can significantly increase metabolic rate for the following three hours. Theoretically, this can help burn more fat, lose weight, and generate more heat.

    Caffeine may escalate energy use even when at rest, so stimulating thermogenesis and increasing the metabolic rate may make it easier for people to lose weight.

    Interestingly, most of this increase in metabolism is caused by an increase in fat burning (3).

    This is seen as very promising for preventing weight gain. However, this effect is more pronounced in lean individuals than those who are obese (4).

    Moreover, it seems to decrease with age and is more noticeable in younger individuals.

    That said, it is also often found in over-the-counter pain relievers as it speeds up the action of ingredients like paracetamol or ibuprofen. It’s believed to help treat or manage a headache, migraine, or drowsiness quicker.

    Enhances Exercise Performance

    Caffeine consumption is also associated with increasing stamina, endurance, and strength, making it highly popular among athletes looking for a performance edge (5).

    This impact is felt via a few different mechanisms.

    First, its effects on the brain enable individuals to exercise harder and longer burning resulting in a more significant calorie burn. Then, it burns calories at rest and also suppresses appetite.

    When caffeine intake is paired with carbohydrates, it improves glycogen replenishment in the body. This is critical for muscle recovery, especially for people who exercise frequently.

    As part of a pre-workout supplement, it may help with both aerobic and anaerobic exercises.

    It blocks adenosine receptors that assist in expanding the duration of the workout. That is why it is a popular addition to several energy drinks.

    Protects Against Heart Disease and Diabetes

    Research indicates that drinking one or more cups of coffee a day may lower the risk of heart problems, but only if it’s caffeinated.

    Recent research shows that there is a definite association between caffeine and reducing the risk of cardiovascular failure.

    Analyzing data from more than 21,000 US adults who participate in three major studies showed that daily coffee consumption of the caffeinated kind lowered the long-term risk of heart failure and boosted cardiovascular health.

    Evidence collected showed that in two of the studies, the risk of heart failure fell by 5-12% per cup of coffee each day compared to having no coffee.

    The third study showed that while one cup of coffee didn’t make a difference, drinking daily two cups of coffee lowered the chance of cardiovascular failure by 30% (6).

    Coffee contains many polyphenols, which may tie into its health benefits for heart disease.

    Polyphenols have antioxidant properties and may offer protection by improving the function of the inner lining of the heart and blood vessels when specific to cardiovascular disease.

    They may also increase protective HDL cholesterol, decrease LDL cholesterol, and promote anti-platelet and anti-inflammatory activity.

    Polyphenols may also exert a beneficial effect on type 2 diabetes by slowing carbohydrate digestion and glucose absorption (7).

    This helps keep blood sugar levels stable. However, anyone with type 2 diabetes should watch their source of caffeine and stay away from caffeinated, sugar-laden beverages.

    Also, anyone with blood pressure issues should talk to their doctor about the amount of caffeine they consume as it can cause hypertension.

    Promotes Liver and Gut Health

    There is mixed evidence regarding the benefits of caffeine in this area.

    A study on the topic showed that consuming as few as one cup of coffee every day produced a 15% decrease in the danger of death from chronic liver disease.

    In contrast, coffee drinkers who consumed 4 cups daily exhibited a 71% decline. This indicates that drinking coffee generated a reaction dependent on the dose.

    However, overall the most significant effects were observed when coffee drinkers had 3 cups of coffee a day (8).

    Drinking coffee has been proved to decrease liver scarring named fibrosis. When this condition progresses into its advanced stage, it is recognized as liver cirrhosis.

    Research shows that consuming caffeine may stall this disease progression.

    One meta-analysis examined data from 16 separate studies with a significantly diminished degree of cirrhosis amongst coffee drinkers compared to others who did not take coffee (9).

    The same benefits have also been observed in different forms of liver disease such as hepatitis B and C, fatty liver disease from alcohol, and non-alcoholic fatty liver disease (10).

    That said, caffeine intake doesn’t heal liver disorders linked to hepatitis C but can benefit patients with this health condition.

    Studies prove that high hepatitis C and fibrosis levels can be reduced among patients who drink coffee instead of others who don’t (11).

    Much of the research points out the beneficial effects of coffee directly with the amount of caffeine consumed.

    Coffee also has its fair share of pros and cons for digestive health. It stimulates gut muscles to promote motility which is good news for individuals suffering from constipation.

    On another level, some preliminary research suggests that regular caffeine consumers have healthier compositions of gut bacteria. While this seems promising, more research is needed to verify this benefit.

    Anti-Cancer Properties

    One of its most promising benefits for health is that caffeine may reduce the risk of some cancers, prolong the survival of others, and does not appear to increase the risk of any cancers.

    Containing hundreds of different compounds, it may boast some anti-cancer properties.

    A large observational study strongly suggests that increasing the amount of caffeine intake for advanced or metastatic colorectal cancer patients (CRC) may be associated with a reduced risk for disease progression and death.

    A review published in the New England Journal of Medicine 2020 concluded that coffee consumption might be associated with a slightly reduced risk of developing melanoma, non-melanoma skin cancer, breast, prostate, and endometrial cancers.

    Individuals who drink coffee are less prone to evolve basal cell skin cancer and malignant melanoma, and their danger declines with each cup people take.

    This study specific to melanoma handed out a food survey to 3.5 million US residents with findings showing that individuals who consumed coffee daily had a lower risk of melanoma compared with others who drank none.

    Those who consumed 1-3 cups each day held a 10% lower risk than others who did not drink coffee at all. And individuals who consumed four or more extra cups presented a 20% lower risk.

    This study does not establish a cause-and-effect relationship between caffeine intake and melanoma. Still, it only investigates an relationship in how much caffeine is consumed and the chance of forming melanoma.

    Preliminary examination corroborates these findings that the amounts of caffeine consumed may be protecting against different types of skin cancer, possibly by mitigating UV damage to skin cells.

    There is also some modest evidence to support the connection linking the amounts of caffeine consumed and a lower risk for prostate, renal cell, and oral cancers.

    Reduces Risk of Parkinson and Alzheimer Diseases

    Some research indicates that caffeine may protect against mental health problems like dementia, including Alzheimer’s disease.

    Some research shows that it may delay the onset of Alzheimer’s even in seniors already suffering from some mild form of dementia.

    This is believed to be caused by blocking inflammation in the brain, specifically adenosine receptors which may trigger memory problems and cognitive decline.

    One CAIDE study showed that drinking 3-4 cups of coffee per day at midlife was linked to decreased risks of dementia and AD by about 65% at late-life (12).

    Another area that explored the benefits of caffeine is in regards to Parkinson’s disease.

    Previous clinical studies have shown that some coffee components can prevent the formation of toxic protein aggregates associated with PD development.

    One study looked at how caffeine may reduce muscle tremors in men with Parkinson’s Disease. Study findings concluded that coffee consumption and tremor severity seemed to be inversely related in male patients.

    One particular fatty acid in coffee called eicosanoyl-5-hydroxytryptamine (EHT) has been getting a lot of attention lately as it may have some protective biochemical mechanisms for PD.

    One comprehensive animal study treated two different PD model mice with either a combination of caffeine and EHT, caffeine alone, or EHT alone to investigate their impact on brain function. The third group of mice received no treatment.

    Study results showed that the untreated mice had increased inflammation, significant neuronal loss, and higher deficits in behavior tests.

    But those treated with different amounts of caffeine or EHT presented minimal or no improvement in any of these measures.

    But the mice that received a combination of caffeine and EHT showed significant improvements in all areas.

    To conclude, researchers found out that a synergistic combination of caffeine and EHT helped slow down neurodegeneration associated with PD in mice (13).

    How To Take Caffeine?

    Caffeine is found in varying amounts in different foods, with some being better sources than others. It is best to opt for natural foods containing caffeine than those laden with sugar and other stimulants.

    Caffeine is easy to incorporate into the diet through food and beverages. It is also available in products like pills and drugs, with the most common being the following:

    • coffee
    • espresso
    • tea
    • chocolate
    • soft drinks
    • energy drinks
    • supplements


    Everybody tolerates caffeine a little differently. Doses as little as 500 milligrams of caffeine and above could potentially present symptoms of caffeine overdose.

    Some people may feel okay with their perceived normal around 500 mg, while others may feel sick or weak very quickly.

    The FDA cites doses of 400 mg as a safe amount of caffeine taken daily. Yet, there is a variation in how it will influence the individual based on their sensitivity and metabolism of caffeine.

    How Long Does It Take Caffeine To Work?

    When taking caffeine orally, it gets absorbed in the blood and body tissues.

    This is a relatively quick process as absorption is virtually complete 45 minutes after ingestion.

    Peak plasma concentration reaches 15-120 minutes after ingestion.

    How Long Does Caffeine Stay in Your System?

    Caffeine can easily stay in the system for four to six hours and even longer for some people.

    It has a half-life of about four hours, although this effect may increase or decrease in specific demographics like expectant women, smokers, or people with impaired liver function (14).

    Does Caffeine Have Side Effects?

    While several caffeine studies have established the stimulant’s positive effects on speedy reaction times, quicker thinking, and mental processing, it has also been associated with specific side effects.

    It’s also true that most of these happen when caffeine intake exceeds or is used by people with sensitivity. There is also the concern of tolerance buildup by those who consume a lot of this substance.

    • Frequent caffeine intake is sometimes associated with high blood pressure. This is because it makes blood vessels narrower, leaving less room for circulation, which raises blood pressure.
    • Adrenal exhaustion is also associated with high caffeine consumption. Consuming caffeine in large amounts causes the adrenals to overwork and burn out the glands.
    • In addition, people with underlying cardiovascular disease should watch how much caffeine they consume.
    • Caffeine habituated people can experience caffeine withdrawal 12-24 hours after their last consumption, which typically resolves in 24-48 hours.
    • Typical caffeine withdrawal symptoms can include a headache paired with weakness, drowsiness, and depression.
    • Other common experiences include irritability and anxiety. These symptoms occur when the brain and body get put in a hyper-aroused state with emotions overrunning behavior.
    • However, its effects on irritability and anxiety are individualized, and symptoms can depend on an individual’s body weight, metabolism, tolerance, and baseline mood.
    • People who are not used to taking caffeine regularly may also experience more frequent headaches.
    • Another side effect is sleep disruption. By binding to adenosine receptors, caffeine lowers melatonin levels and interferes with sleep. Anyone who experiences disturbed sleep should discuss their intake with their doctor to see if caffeine is not letting them sleep properly.
    • Mixing caffeine with alcohol is never recommended as the former’s stimulant effects can mask the latter’s depressant effects. Also, since both are diuretics, combining caffeine with alcohol can concern water loss and dehydration.
    • While caffeine does not pose the threat of a stroke, care is cautioned for individuals with severe hypertension, cardiovascular disease, or seizures.
    • Consumption is discouraged for breastfeeding women as small amounts can pass into breastmilk, building up in the baby over time.

    In the end, it all comes down to how well an individual tolerates caffeine and how this drug is consumed. Caffeine holds the potential to make everyone feel differently, so it’s possible that even a small dose can have both good and bad effects.

    And because it’s not hard to develop a caffeine tolerance, it’s also not difficult to overdose on the stimulant.

    The Danger of Energy Drinks

    Energy and sports drinks are beverages touted to enhance physical activity and advertised as safe for consumption.

    However, given their high content, too much caffeine paired with sugar and other additives, these drinks can easily lead to an overdose of caffeine unknowingly.

    Since these products are advertised as natural dietary supplements, they are not even subject to regulations that apply to other food products.

    If consumption isn’t kept in check, users may often experience caffeine effects like headaches, heart palpitations, insomnia, and restlessness.


    So, while caffeine does attract its fair share of bad press, consuming a sensible amount can be good for you.

    Caffeine makes you feel more alert, productive and motivated while reducing fatigue with its high antioxidant content.

    It also holds the potential to protect against certain diseases and packs a punch when you’re looking to up energy levels.

    The key is to have it in moderation so that you minimize any chance of tolerance and enjoy it as part of your daily routine.


    Is caffeine addictive?

    Individuals with regular caffeine intake can develop a dependence on it quite quickly.

    This happens when the need for the stimulant crosses the line from a pleasant pick-me-up daily to a necessity.

    Does caffeine actually give energy?

    Caffeine intake does not do much to supply calories (units of energy), but it provides an energy kick that temporarily affects the brain’s receptors.

    Can you develop a caffeine sensitivity?

    Caffeine sensitivity can increase with age as it becomes harder to metabolize it.

    How come caffeine doesn’t affect me?

    Individuals who don’t feel affected by caffeine may already be taking it in large servings and have developed a tolerance.

    Or, there may be other health and genetic factors at play that metabolizes it much faster.