Caffeine is definitely having its moment, being available in any number of beverages, foods, and supplements—all ready to give your workout a boost or get you through that mid-afternoon slump.
There’s also a host of new research showing health benefits of everyone’s favorite caffeine-containing beverage: Coffee!
Why then do some people still smugly tell you they avoid caffeine? Is there any truth to those myriad rumors about caffeine (bad for your heart, dehydrating, increases diabetes risk, and so on…)?
This article will answer all your questions. You’ll be able to set the naysayers right and provide fascinating facts about caffeine such as that it can improve athletic performance by 20 to 25 percent or that coffee is reported to have been discovered in 9th century Ethiopia when a shepherd began consuming wild coffee berries after observing that his goats had increased energy after eating them (1, 2)!
Let’s start with some of the potentially bad things about caffeine, since these are more controversial.
#1: Is Caffeine Dehydrating?
Ask around and probably 98 percent of people will tell you “caffeine is dehydrating. It’s like drinking negative water!”
Nope. Although, caffeine has a slight diuretic effect, meaning it leads to a small increase in urine output, this effect is not substantial enough to impact whole body hydration (3,5). Plus, it goes away if you exercise after, so concerns of dehydration in athletes who take it prior to competition is unwarranted (4).
“But I always have to pee more when I drink coffee!”
Think about it: You’re consuming a beverage, so your fluid intake is increased, leading to greater urine production just like if you were drinking water or decaf coffee.
The one possible time you might want to make an extra effort to hydrate with water is if your taking caffeine pills since these don’t come in a beverage. Again, there’s no evidence of increased dehydration but the reality is that many people still don’t drink enough water and it’s possible that if you’re taking caffeine to fight tiredness or increase focus, you’ll be so dialed in you’ll forget to drink as often as you should.
The bottom line is that as long as you drink normal amounts of liquid, dehydration is not something you need to worry about when it comes to caffeine.
#2: Caffeine Can Inhibit Sleep
Probably the most wonderful but terrible thing about caffeine is that it can keep you awake. Wonderful because we all need a little pick-me-up sometimes, and in this increasingly hectic world, caffeine may literally save us when we are sleep deprived. For example, caffeine can reduce your inclination to take dangerous risks when exhausted. It’s also been shown to enhance mental acuity and physical precision in sleep deprived surgeons.
But caffeine use can backfire, especially when people don't realize how much it’s impacting their sleep. There’s the obvious vicious cycle in which we consume it, don’t sleep well, and the next day feel tired, so we consume more, further disrupting that night’s sleep.
Research shows caffeine can actually shift our circadian clocks, altering hormone release so that the sleep-hormone melatonin is delayed, while genes and cells that regulate our biorhythms are negatively impacted (6). Your whole physiological system gets changed, which is hard to recover from and will only make your experience of fatigue and sleeplessness worse.
You might think that drinking coffee in the morning and then abstaining all day long can’t negatively affect your sleep. But this isn’t necessarily so.
Some people are much more sensitive to caffeine due to different genotypes that lead to a difference in how the body metabolizes caffeine (7). Age, stress levels, and mental health also impact how you respond to caffeine. Further, endocrine imbalances, which appear to be more common due to obesity, increased chemical exposure, and (surprise!) lack of sleep) also make it harder to metabolize caffeine.
The bottom line is to use common sense: If you have trouble sleeping it is a no-brainer to avoid caffeine after 12 pm. If the problem continues, try reducing your intake or wean yourself off it altogether. Not an easy task, we know, but could be worth the pain and struggle!
#3: High Caffeine Intake May Be Harmful To Pregnancy
Pregnant women should probably limit their caffeine intake based on the fact that caffeine is rapidly absorbed and crosses the placenta freely. A fetus does not possess the enzymes involved in caffeine metabolism. This may be associated with impaired fetal growth, resulting in low birth weight (8).
Experts recommend pregnant women limit caffeine intake to less than 100 mg/day (less than one cup of coffee) and that women who are trying to get pregnant limit caffeine intake to less than 300 mg daily (9). Of course, it doesn’t take a genius to realize that since it’s difficult to reduce caffeine intake quickly, it’s probably a smart move for women who are trying to get pregnant to actively work on reducing their caffeine intake below the 100 mg dose in order to avoid withdrawal symptoms once they become pregnant.
#4: Caffeine Increases Cortisol. Is This A Problem?
There’s much concern about caffeine’s effect on the stress hormone cortisol. Whether this is a problem is unclear. New caffeine users experience a large spike in cortisol that lasts throughout the day. The same thing happens if you abstain from consuming caffeine for five days.
Once you become habituated to having caffeine in the morning, the cortisol spike is abolished. However, if you consume additional caffeine in the afternoon, cortisol will be elevated, indicating that chronic use throughout the day is problematic for stress hormone regulation. In addition, caffeine has been found to act in in concert with mental stress to raise cortisol levels higher than they would be in the absence of caffeine.
Research into the effects of caffeine, exercise, and the post-workout increase in cortisol are inconclusive. One study found that combining caffeine with moderate aerobic exercise resulted in a cortisol spike. A second study of male athletes had a different outcome. Using a caffeinated chewing gum during 20 repeated sprints resulted in a reduction of cortisol of 21 percent relative to a placebo after the workout.
Caffeine also increases anxiety, which can increase cortisol release and the overall experience of stress. This effect may be greater in certain genotypes. One study found that people with certain genetic markers had a significant increase in anxiety after consuming a relatively small dose of just 150 mg of caffeine (11). Related negative effects of caffeine include jitteriness, heart palpitations, and panic attacks.
Whether you should use caffeine all comes down to your individual situation and how you respond to caffeine and stress. It goes without saying that if you suffer from anxiety, unpleasant side effects, can’t sleep, or are struggling with unbalanced cortisol levels, you should probably avoid caffeine. If anxiety and stress aren’t a big issue for you, caffeine has many benefits, as you’ll see below.
Reasons To Use Caffeine:
#1: The Most Effective Legal Performance Enhancing Aid Available
Because caffeine increases fat burning and reduces pain, it’s great for boosting endurance performance and work capacity, but it also has benefits for power athletes, increasing stimulatory hormones for increased jump performance and running speed (12, 13). Lab based studies show performance benefits of 20 to 25 percent, which translates to real-world benefits of 5 to 10 percent (14).
#2: Reduces Post-Workout Muscle Soreness
Caffeine appears to be one of the most effective supplements for reducing the debilitating delayed onset muscle soreness that plagues trainees after tough workouts. It also helps restore strength to baseline levels, which can make all the difference in your performance (15).
#3: Improves Reaction Time
Caffeine block adenosine receptors in the brain, which increase fatigue and are associated with a decrease in how fast your motor neurons fire, slowing reaction time (16). By keeping adenosine from binding, caffeine can blunt fatigue and improve the stimulatory response for a faster response to incoming information.
#4: Improves Concentration & Information Processing
In addition to blocking adenosine from binding, caffeine increase stimulatory brain molecules, dopamine and norepinephrine for enhanced cognition and recall (17).
#5: Boost Mood & Decrease Depression
It’s no coincidence that we often get coffee with friends since it is a natural mood booster, increasing happiness, well being, and sociability. Caffeine use also reduces depression and is linked with a 45 percent lower suicide rate (18, 19).
#6: Reduce Obesity
Because caffeine stimulates metabolic rate and fat burning, regular consumption is associated with a lower body weight. It’s also being considered as an effective treatment for weight management (9). That said, if you have unhealthy habits, caffeine is unlikely to help you lose body fat or maintain a healthy weight. Best results will come from smart caffeine use combined with strength training, regular physical activity, a healthy diet, and sufficient sleep.
#7: Reduce Alzheimer’s & Parkinson’s Risk
Caffeine has many therapeutic effects on the brain, making it protective against deterioration that leads to brain disorders like Parkinson’s and Alzheimer’s. Additionally, caffeine use may slow the progression of these diseases. In the case of Parkinson’s, a disease characterized by a progressive loss of dopaminergic neurons, caffeine can improve activity of these receptors (9).
#8: Protect Against Sunlight-Induced Skin Cancer
Caffeine appears to protect cells from mutations in response to UV radiation that causes DNA damage and leads to the progression of cancer tumors in the skin (9, 20).
#9: May Reduce Type 2 Diabetes
Studies consistently show a beneficial link between reduced risk of diabetes and caffeinated coffee consumption, however, we don’t know if it is the caffeine that is having the effect or other components of coffee (9). If you’re getting your caffeine through sugary soda, it may well be harmful, reducing insulin sensitivity and increasing body fat. The easy solution is to avoid all sugary beverages and get your caffeine from black coffee.
#10: May Lower Risk Of Heart Disease
People who drink caffeinated coffee appear to have lower rates of hear disease and stroke. Just like with diabetes, we don’t know if this beneficial effect would be present from caffeine supplementation without the antioxidants provided in coffee (21, 22, 23).
And despite what you may have heard, caffeine doesn’t appear to raise heart rate or blood pressure chronically. New users will experience a temporary increase in both, which normalizes once you get habituated to caffeine use. That said, certain genotypes are more susceptible to the effects of caffeine and may want to avoid it if they have high blood pressure or are at risk of heart disease.