BTN News: Caffeine is something many of us consume daily, whether it’s in our morning coffee, afternoon tea, or favorite energy drink. It’s a stimulant that can provide a much-needed boost, especially when we’re feeling sluggish. However, recent concerns have surfaced after a popular lemonade brand in the United States was suspended due to accusations that its caffeine content was dangerously high, even though it was reportedly within the recommended daily intake for adults. This has sparked discussions about how much caffeine is too much and whether the source of caffeine really matters. While caffeine has been linked to various health benefits, there’s still uncertainty about the best ways to consume it.
How Caffeine Affects Your Body
Caffeine impacts our bodies by interacting with a naturally occurring chemical called adenosine. Adenosine plays a crucial role in regulating several body functions, including heart rate, blood flow, and sleep-wake cycles. It makes us feel tired as the day progresses. According to Kenneth Jacobson, a molecular recognition expert at the National Institute of Diabetes and Digestive and Kidney Diseases in the U.S., adenosine is produced in the body to reduce the activity of various organs under stress or high energy demand.
When we consume caffeine, it competes with adenosine for receptors in the body, particularly in the brain. By blocking adenosine, caffeine prevents it from making us feel sleepy, which is why we feel more awake and alert after consuming it. Additionally, caffeine can increase levels of neurotransmitters like dopamine and adrenaline, further enhancing our alertness and sense of stimulation. Damian Bailey, a professor of physiology at the University of South Wales in the U.K., explains that caffeine stimulates the brain, much like how exercise stimulates muscles.
Health Benefits of Caffeine
There’s a significant amount of research on the effects of caffeine, particularly from coffee, one of the most common sources of caffeine worldwide. A comprehensive review of over 200 meta-analyses conducted in 2017 found that drinking three to four cups of coffee daily was more often associated with health benefits than harm. However, studies that showed negative effects could often be explained by a higher proportion of coffee drinkers who also smoked.
One area where caffeine’s effects are more complex is heart health. A study involving nearly 19,000 people found that while drinking more than two cups of coffee daily was linked to an increased risk of death from heart disease among those with high blood pressure, this was not the case for individuals with normal blood pressure. A review of evidence suggested that moderate coffee consumption might reduce the risk of death, high blood pressure, and heart failure, although there was no clear effect on coronary heart disease risk.
Caffeine has also been shown to improve exercise performance. Research on amateur cyclists found that caffeine could boost physical performance by up to 1.7%. Additionally, caffeine has been linked to a reduced risk of several forms of cancer, heart disease, and type 2 diabetes. It has also consistently been found that coffee, but not tea, protects against depression. Jacobson notes that caffeine and other adenosine antagonists may benefit the aging brain, including those with neurodegenerative diseases like Alzheimer’s. Some studies have associated caffeine consumption with up to a 60% lower risk of developing Alzheimer’s, possibly due to caffeine’s ability to improve blood flow to the brain.
Moreover, coffee has been associated with healthy gut microbiomes, partly due to its bioactive polyphenols and alkaloid compounds, including caffeine. A well-balanced gut microbiota composition can have far-reaching health effects.
However, it’s important to note that not all of coffee’s health benefits are related to caffeine. For example, chlorogenic acid, a compound unique to coffee, may play a role in its beneficial effects on diabetes, as suggested by Marilyn Cornelis, an assistant professor of Preventive Medicine and Nutrition at Northwestern University in the U.S. Decaffeinated coffee has also been shown to reduce diabetes risk, indicating that caffeine may not be the primary factor.
Different caffeinated beverages can have varied effects depending on their other components. This is true even for different types of coffee. For example, roasted coffee contains bioactive compounds with antioxidant and anti-inflammatory properties. While instant coffee has more beneficial polyphenols than filtered coffee, it also contains more acrylamide, a carcinogen, according to Alex Ruani, a doctoral researcher in Nutritional Science Education at University College London. Tea also has similar anti-inflammatory effects due to its flavanol content.
Sources of Caffeine and Their Effects
Coffee may be the most well-known source of caffeine, but tea is also a strong contender. According to Bailey, strong black and green tea can have a significant caffeine impact. A study that followed over half a million coffee drinkers for two decades found that those who drank filtered coffee had lower rates of arterial disease and mortality compared to those who didn’t drink unfiltered coffee. The researchers suggested that this might be due to the caffeine content.
Interestingly, substituting some coffee with tea might offer additional health benefits, as a study found potential advantages in replacing coffee with tea rather than drinking coffee alone.
Energy drinks, a more recent trend, also contain caffeine. These drinks, which often include other ingredients like sugar and additional stimulants such as guarana, have become increasingly popular. Guarana seeds contain about four times more caffeine than coffee beans, and the natural chemicals in guarana can enhance its stimulating effects compared to caffeine alone.
Research shows that some of the most popular caffeinated energy drinks in the U.K. and U.S. contain between 75 and 160 mg of caffeine, but some can have as much as 500 mg. These drinks often include other stimulants like B vitamins, L-carnitine, L-theanine, and glucuronolactone, which can alter various body systems, including the brain and heart. Over time, this combination of ingredients can lead to heart damage, such as hypotension and arrhythmia, as well as neurological disorders like panic attacks and seizures, according to Ruani.
Timing Your Caffeine Intake
The timing of caffeine consumption is crucial, whether you’re trying to stay awake during a meeting or improve your endurance at the gym. Bailey explains that caffeine levels build up in the bloodstream after 20 minutes, peaking after about an hour. Caffeine can significantly enhance performance if taken an hour before exercise because it helps muscles contract more forcefully and increases fatigue tolerance.
Some researchers suggest waiting 90 minutes to two hours after waking up before having your first cup of coffee. The idea is that the adenosine bound to receptors when you wake up gradually clears away, making it more effective for caffeine to bind to those receptors later. However, this theory is not universally accepted, with some researchers questioning its scientific validity.
While caffeine enters the intestines relatively quickly, its effects can linger for hours. Experts recommend taking your last dose of caffeine about nine hours before bed to avoid interfering with sleep.
When to Avoid Caffeine
Pregnant women are generally advised to limit caffeine intake to 200 mg per day. However, an analysis of 37 studies found that caffeine significantly increased the risk of adverse pregnancy outcomes, including gestational diabetes, preeclampsia, and restricted fetal growth. Caffeine crosses the placenta easily, and research has shown that even small increments of 100 mg of caffeine can increase the risk of miscarriage and stillbirth, with low birth weight starting at just 10 mg per day.
Caffeine also passes through breast milk to nursing infants, who cannot metabolize it effectively. Jack James, a professor at the University of Reykjavík in Iceland, notes that while the concentration of caffeine in a baby’s blood is lower than in the mother’s, the exposure could lead to withdrawal symptoms in infants. Caffeine has been shown to interfere with sleep in adults, leading to physical dependence, as evidenced by a wide range of withdrawal symptoms. These symptoms can occur as soon as six hours after abstaining from caffeine, especially among daily consumers, and can include headaches and irritability.
While few studies have been conducted on caffeine withdrawal symptoms in infants, it’s reasonable to assume that any effects similar to those experienced by adults could be harmful.
Caffeine doesn’t just make it harder to fall asleep; it can also reduce the amount of deep sleep you get, according to Ruani.
How Much Caffeine Is Too Much?
The European Food Safety Authority (EFSA) advises healthy adults not to exceed 400 mg of caffeine daily and no more than 200 mg in a single drink. The general consensus seems to be that consuming 200 to 300 mg of caffeine per day is better than not consuming it at all, according to Bailey. However, recommendations can be tricky to follow when we don’t know how much caffeine is in a given drink, and the content can vary widely.
Assuming an average of 100 mg per cup of coffee, 400 mg would be four cups a day, but Bailey points out that four Flat Whites would be well over the 400 mg limit. This is because different coffee bean varieties, the amount of ground coffee used, and the preparation method can all influence the caffeine content.
“Providers often aren’t aware of how much caffeine they’re serving,” Bailey says. “An espresso can contain anywhere from 250 mg to 700 mg of caffeine, and some energy drinks can have 500 or 600 mg.”
It’s easy to overload on caffeine, Bailey adds, and you’ll know when it happens because you might start feeling nauseous, anxious, irritable, and get a headache. You may also experience premature ventricular contractions, which are extra heartbeats due to the heart’s pacemakers becoming irritated.
However, a moderate intake of about two to three cups of coffee per day hasn’t been linked to any severe side effects in healthy individuals, according to Jacobson. If you need to stop consuming caffeine suddenly, he advises doing so gradually over a few days to avoid withdrawal symptoms.
Individual Differences
There are at least eight genes associated with caffeine intake that we inherit, including those influencing neurological stimulation, the psychoactive effects of coffee on the brain, how quickly we metabolize coffee, how much we can tolerate, and how much we enjoy it, Ruani explains.
It can take as little as two hours to metabolize half the caffeine consumed, but for some people, it can take more than 12 hours, Cornelis adds. This difference is mainly due to genetic variants in the CYP1A2 enzyme, responsible for over 90% of caffeine metabolism.
There tend to be two categories of people: those who respond to caffeine and those who don’t. You probably know which category you fall into. Most people’s coffee habits align with their genetic predisposition, Cornelis says, as we’re good at determining how much coffee we can tolerate and staying within our individual tolerance levels.
However, this is where the health benefits associated with caffeine become more complicated. Those who metabolize coffee quickly may need to consume more to reap health benefits because the effects wear off quickly, Cornelis notes.
Our genetic differences can also influence how much habitual coffee consumption promotes health benefits. “Some people may develop high blood pressure from drinking caffeinated beverages, while others don’t,” Ruani says. “Some benefit from caffeine’s heart-protective effects, and others don’t.”
These individual differences may contribute to some of the conflicting findings regarding coffee’s health benefits.
Conclusion
Caffeine is a unique drug because it’s so readily available. However, this accessibility makes it even more important, though perhaps more challenging, to consume it in moderation. If you find it hard to relax and feel jittery, you may have reached your caffeine limit, Bailey suggests. But the real telltale sign, he adds, is difficulty sleeping at night.
“Always avoid coffee after dinner and opt for decaf instead,” Bailey advises. “Sleep is incredibly important for the brain.”
