Most American adults drink coffee, and two thirds of us drink it every day. We drink it for its aroma and flavor. We drink it for the routines and social activities built around it. Even people who don’t drink it take “coffee breaks” and “meet for coffee.”
But the main reason we drink it is how it makes us feel. Coffee perks us up, boosts energy and mood, and improves focus, productivity, and overall mental function—and these are only the obvious benefits. Coffee consumption is also linked with a reduced risk of several chronic diseases and premature death.
The compound in coffee that is responsible for most of these attributes is caffeine, a rapidly absorbed and fast-acting central nervous system stimulant. Let’s take a look at its many benefits, as well as a few cautions about caffeine.
Caffeine & Brain Health
Caffeine’s psychoactive properties—its effects on the mind—are related to adenosine. Adenosine acts as an inhibitory neurotransmitter in your nervous system, binding to receptors in your brain, slowing down neural activity, causing drowsiness, and promoting sleep.
The secret to caffeine’s energy-boosting actions is that it’s very similar in structure to adenosine. So, it easily binds to these same receptors, displacing adenosine and blocking its “sleepy effects.” Rather than slowing down neural activity, caffeine speeds it up. This, in turn, triggers the release of the stress hormone epinephrine (adrenaline), which activates the autonomic nervous system and prepares you for action.
Stress has negative connotations, and excessive stress is certainly harmful, but there are positive aspects as well. By mildly stimulating the stress response, caffeine boosts energy, alertness, and mental performance. It gets us going, motivates us, and impels us to achieve our goals. Studies have shown that even at low doses, caffeine quickens reaction time and sharpens alertness, attention, and the ability to process and retain new information.
Does caffeine affect memory? It does enhance short-term memory to some degree. Perhaps more importantly, research suggests it may protect against age-related memory loss and the development of Alzheimer’s and other neurodegenerative diseases such as Parkinson’s.
Caffeine Boosts Physical Energy, Endurance & Fat-Burning
Athletes have known for years that caffeine improves performance when taken prior to exercise. As a central nervous system stimulant, it boosts energy and increases blood flow and oxygen delivery to the muscles. In addition, it reduces the perception of fatigue and pain and sharpens mental focus, which is another edge for competitive athletes.
Caffeine also modestly increases the body’s ability to burn fat. This is particularly advantageous during endurance activities, when glycogen, which fuels your muscles during long bouts of exercise, may be depleted.
This leads to an obvious question. Does caffeine help you lose weight? It does increase metabolism and fat-burning, but this effect is considerably more pronounced in lean vs. heavy individuals. Many people swear that drinking coffee also suppresses appetite. Although caffeine is included in many weight loss supplements, the research is not definitive, and the jury is still out.
You may have heard that caffeine can cause heart problems, but this has been disproven. Caffeine’s stimulating effects may temporarily raise blood pressure and increase heart rate—especially if you don’t drink it regularly. But, like exercise, this actually makes the heart stronger over the long run. Another myth is that caffeinated coffee increases the risk of atrial fibrillation or other cardiac arrhythmias. A 2021 study found that habitual caffeine consumption is actually linked with a lower risk of arrhythmias. All told, moderate caffeine intake is associated with better cardiovascular health.
The Downside of Caffeine
Of course, you can get too much of a good thing. Excessive caffeine can make you feel jittery, anxious, and irritable. Once the caffeine “high” wears off, you may feel tired and unfocused. A common solution is to have another cup of coffee and start the cycle all over again.
The natural acids plus the caffeine in coffee can also cause stomach upset, bloating, and other gastrointestinal issues, especially when combined with the sugars and creamers that are often added. The junk that many people take in their coffee turns a healthy brew into a high-calorie, chemical-laden health hazard.
Caffeine can interfere with sleep as well. It has a half-life of around six hours, so about half of the caffeine in that afternoon cup will still be in your system at bedtime—blocking adenosine receptors and preventing the natural slowdown of brain activity that helps you sleep.
I have been asked if coffee is addictive. Going cold turkey may result in headaches, sleepiness, and difficulty concentrating for a couple of days, but this is suggestive of mild physical dependence, at worst.
All told, the pros of caffeine far outweigh the cons.
Coffee, Tea, or Supplements?
Most adults get their caffeine in coffee and tea. The average eight-ounce cup of coffee contains 100 mg of caffeine, and a cup of brewed tea has 25–45 mg. However, levels vary significantly based on brewing methods, types of coffee beans or tea leaves, and, of course, serving sizes. A brewed Starbucks grande (their medium 16-ounce size) contains about 350 mg of caffeine.
Caffeine is also added to sodas and energy drinks. Coke, Pepsi, and other caffeinated soft drinks average 35–55 mg per can, and energy drinks like Red Bull have around 10 mg per ounce. These beverages also contain a lot of sugar, artificial sweeteners, and/or other additives that have no place in a healthy diet; stay far away from them. Chocolate is another natural source of caffeine, especially dark chocolate, which may have 12–20 mg per ounce. Yet, even with dark chocolate’s numerous health benefits, you should enjoy it only in small amounts.
A number of supplements for focus or energy contain caffeine, and I recommend them for some of my patients. Judicious doses of natural caffeine, in the 50–100 mg range, along with other energy and brain boosters like ginseng provide a nice pick-me-up when you’re struggling to concentrate or wake up. A small, controlled dose of caffeine, especially when combined with other natural ingredients, can help you get past a midday slump without the jittery feeling that coffee can cause.
How Much Is Too Much?
The usual recommendation is up to 400 mg of caffeine per day, although some of the studies showing benefits of coffee give the thumbs-up to eight cups or more.
I cannot make a blanket recommendation because not everyone responds to caffeine in the same way. Genetic variations in how the body metabolizes caffeine affect how it makes us feel and how much we drink.
Some people are quite sensitive to caffeine. One cup of coffee makes them jumpy and interferes with their sleep. Others, who are genetically hardwired to rapidly metabolize caffeine, can drink it by the potful. Listen to your body, recognize the signs of overindulgence, monitor your intake accordingly, and check with your doctor to determine what is most appropriate for you.
On the other hand, don’t overlook the benefits of caffeine. If coffee doesn’t agree with you, try black or green tea or an energy or focus supplement with 50–100 mg of natural caffeine.