Does caffeine have any negative effects? Is caffeine actually good for you? How much caffeine should you have in a day? Nutrition Diva tells all.
Are you a regular coffee drinker? Do you sometimes worry that caffeine might be bad for your health? Well, there’s no need to feel guilty about your little coffee habit. In fact, caffeine has been found to have a lot of positive health benefits and, despite what you may have heard, relatively few drawbacks.
Positive effects of caffeine
People who drink coffee every day have a significantly lower risk of diabetes, Parkinson’s, colon cancer, gallstones, and Alzheimer’s disease. Now, that may not all be due to caffeine. Coffee contains a lot of volatile compounds and antioxidants that may have beneficial effects by themselves, or in combination with caffeine.
For example, drinking tea doesn’t seem to reduce your risk of diabetes, even though tea contains caffeine. On the other hand, people who drink decaffeinated coffee do have a reduced risk, but decaf only seems to work about half as well as caffeinated coffee.
It’s definitely the caffeine that protects against Parkinson’s and Alzheimer’s, though. Not only does caffeine stimulate the brain and central nervous system, but it appears to protect it as well. Caffeine doesn’t make you any smarter but it does makes you more alert and boosts your ability to concentrate, which can make you a better test taker or a better driver.
The benefits of caffeine start kicking in when you consume a cup of coffee or a couple of cups of black tea every day. The positive effects really start piling up when you drink three or four cups of coffee a day or the equivalent. People who drink seven or eight cups a day may get even a little more benefit in terms of neuroprotection, but also have a higher risk of ill effects, such as jitters, agitation, or sleep disruption.
Does caffeine cause or treat headaches?
Caffeine can also relieve headaches. In fact, the popular headache medicine Excedrin contains as much caffeine as a big cup of coffee. Headaches, especially tension-type headaches, are often accompanied by increased blood flow to the brain. Ths puts pressure on the nerves and causes pain. Caffeine is a vasoconstrictor, meaning that it constricts blood vessels, and this can relieve headache pain. In fact, adding caffeine to a pain reliever like Tylenol can increase the effectiveness by up to 40%.
If you drink coffee, tea, or other caffeinated beverages regularly, stopping suddenly can also bring on a headache. In fact, it's hypothesized that caffeine withdrawal may contribute to post-operative pain -- because patients typically skip their regular morning cup on the day of surgery. And one study even found that adding a bit of caffeine to the IV liquid for patients recovering from surgery made them quite a bit more comfortable! It can also help people shake off the effects of anesthesia more quickly.
Does caffeine make you a better athlete?
Caffeine also enhances athletic performance. In fact, up until recently, caffeine was considered a performance-enhancing drug by the International Olympic Committee and athletes had to keep their intake of caffeinated beverages fairly low to pass their drug screens. Unlike most performance-enhancing drugs, you can safely try this one at home. Have a cup or two of coffee one hour before your workout and you may be able to go a bit faster, stronger, and longer. This effect may be enhanced if you abstain from coffee for a week or two.
Brock Armstrong of the Get-Fit Guy podcast recently dedicated an episode to using caffeine to enhance your athletic performance.
Myths about caffeine
Many of the negative things you’ve heard about caffeine are actually myths, several of which I’ve debunked in previous shows. It’s a myth, for example, that caffeine weakens your bones, as I explained in my episode on nutrition for healthy bones.
It's also a myth that caffeine consumption is liked to fibrocystic changes, or benign lumps, in the breast. Trial after trial has found no connection between caffeine or coffee consumption and breast lumps or fibrocystic breast disease. Women who suffer from breast pain and tenderness are often counseled to give up caffeine. And one small study found that 61% of women who cut out (or cut down on) caffeine had improvement of their symptoms. However, this study included no control group. And other research has found that breast pain tends to resolve on its own after a few months. So it's impossible to say whether avoiding caffeine was responsible for the reduction of breast pain.
And, as I explained in the dehydration myth episode, caffeinated beverages are not dehydrating. Caffeine is a diuretic, meaning that it makes you pee more. But the fluids in coffee and tea more than replace any fluids that you lose due to the diuretic effect. Not only that, but if you drink coffee regularly, it loses it's diuretic effects.
Keep in mind, though, that caffeine pills don’t contain any fluids and, therefore, can be dehydrating.
Finally, you might have heard that caffeine or coffee is bad for your heart. Some studies have found that drinking unfiltered coffee—such as French press or percolated coffee—elevates cholesterol. It appears to be volatile oils in the coffee rather than caffeine that affect cholesterol, and only in men. But coffee drinkers are no more likely to develop heart disease.
Coffee can also cause a temporary increase in your blood pressure but this is not thought to be a concern. And although caffeinated coffee can also temporarily increase your heart rate a bit, it does not cause irregular heartbeat. In fact, an as yet unpublished study presented at the 2020 meeting of the Heart Rhythm Society found that coffee consumption is associated with a lower risk of arrythmias.
Negative effects of caffeine
There are some legitimate downsides of caffeine but they are relatively minor. Some people find that caffeines make them jittery, anxious, or disrupts their sleep. How many cups of coffee it takes to make your hair stand on end, or how late in the day you can drink a cup of coffee without staring at the ceiling all night, are subject to a high degree of individual variation.
People who are very sensitive to stimulants are usually better off avoiding caffeine altogether. For everyone else, moderate consumption of caffeine appears to have a lot of benefits and limited disadvantages. The alert listener will have noted that I have once again invoked the “M” word: Moderation. Here are your parameters for moderate caffeine consumption:
How much caffeine is too much?
National health advisory committees in The U.S., Canada, and Europe agree that 400 mg of caffeine per day is perfectly safe for most healthy people. That's the amount you'd get in 2-3 cups of brewed coffee. (Some energy drinks have up to 300 mg per can.)
Large amounts of caffeine could negatively affect the growth and development of babies in the womb. Women who are pregnant, planning to become pregnant, or breastfeeding are advised to limit their intake to 200 mg per day or less.
Under normal circumstances, it takes about 5 hours for half of the caffeine you consume to be cleared from your system. Because caffeine can negatively affect sleep quality, you're well advised to avoid drinking caffeinated beverages with 5 to 8 hours of bedtime.
There's really not a lot of data on safe amounts of caffeine for kids or adolescents, which is a concern given the popularity of high-caffeine energy drinks. Some agencies have recommended that kids keep their caffeine intake well under 100 mg per day, which would be the amount in two cans of caffeinated soda. Other experts feel that even that might be unwise.
What is caffeine found in?
Coffee is the primary source of caffeine in the American diet. (Interestingly, it's also the primary source of antioxidants--by a large margin!) But varying amounts of caffeine are also found in black and green tea, soda, energy drinks, chocolate, as well as some over-the-counter pain relievers and dietary supplements.
This infographic, created by Examine.com, shows the amount of caffeine in many popular beverages.