Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks.
For healthy adults, the FDA has cited 400 milligrams a day—that's about four or five cups of coffee—as an amount not generally associated with dangerous, negative effects.
According to the Dietary Guidelines for Americans, it's safe for most women to drink three to five cups of coffee a day with a maximum intake of 400 milligrams of caffeine. (Caffeine content can vary depending on the type of coffee, but an average 8-ounce cup has 95 milligrams.)
Drinking 2 to 3 cups of coffee a day was associated with equivalent reductions in the incidence of cardiovascular disease and death from cardiovascular disease or any cause, said study author Peter Kistler, MBBS, PhD, head of clinical electrophysiology research at the Baker Heart and Diabetes Research Institute in ...
If you are wondering how much is too much, a review published in November 2017 in the journal Food and Chemical Toxicology found that intake levels of up to 400 mg a day, or about four 8-ounce cups of coffee, are not associated with health risks for adults.
Coffee still has potential risks, mostly due to its high caffeine content. For example, it can temporarily raise blood pressure. Women who are pregnant, trying to become pregnant or breastfeeding need to be cautious about caffeine.
In this battle over health benefits, coffee comes out on top. Coffee drinkers can raise a mug to fiber, microbiome health and lowering risk for cancer and diabetes. But tea drinkers, do not despair. Tea is undoubtedly good for your blood pressure, cholesterol, stress levels, mental health and productivity.
Caffeine is a stimulant, which means it increases activity in your brain and nervous system. It also increases the circulation of chemicals such as cortisol and adrenaline in the body. In small doses, caffeine can make you feel refreshed and focused.
And studies show coffee may protect against liver disease. Most of the benefits are thanks to antioxidants. A large 2021 study found that drinking coffee was associated with a lower risk of liver disease. Effects were similar for both regular and decaf coffee.
Research has not shown that drinking 3-4 cups of coffee a day increases the risk of kidney disease or increases rate of decline of kidney function. However, moderating how much coffee you drink is a good idea. Those struggling with blood pressure control should especially drink less than three cups per day.
Drink it black
The healthiest way to drink coffee is plain with nothing added — also known as drinking it black. Dr. Hashmi explains, “Ideally, you shouldn't put sugar in your coffee.
The coffee diet encourages you to drink at least 3 cups (720 ml) of coffee per day while restricting calorie intake. Though it may result in short-term weight loss, it's not a healthy diet in the long run. It can lead to weight regain and adverse effects from excessive caffeine intake.
Due to its stimulating effects, caffeine has been linked to health benefits like enhanced alertness, improved athletic performance, elevated mood, and increased metabolism ( 4 , 5 , 6 , 7 ).
Moderate caffeine consumption might boost memory. Recent Johns Hopkins University research indicates that caffeine may enhance long-term memory.
Caffeine and memory
Some studies suggest that caffeine may have a significant positive effect on both short-term and long-term memory ( 12 , 13 ). Other studies report no effects on memory or have even found that caffeine impaired performance on memory tasks ( 13 , 14 , 15 ).
According to the FDA, the half-life of caffeine is between four and six hours. This means that up to six hours after drinking a caffeinated beverage, half of the caffeine you consumed is still present in your body — keeping you alert. And, if it's bedtime, keeping you from falling asleep.
“For most people, moderate coffee consumption can be incorporated into a healthy diet.” Hu said that moderate coffee intake—about 2–5 cups a day—is linked to a lower likelihood of type 2 diabetes, heart disease, liver and endometrial cancers, Parkinson's disease, and depression.
Is decaf coffee bad for you? Like all coffee, decaffeinated coffee is safe for consumption and can be part of a healthy diet. If you are wondering whether the decaffeination process itself is safe, the answer is yes.
Drinking caffeine-containing beverages as part of a normal lifestyle doesn't cause fluid loss in excess of the volume ingested. While caffeinated drinks may have a mild diuretic effect — meaning that they may cause the need to urinate — they don't appear to increase the risk of dehydration.
Not partaking in caffeine can be good for your blood pressure. Caffeine has been shown to raise blood pressure levels due to the stimulatory effect it has on the nervous system. High intake of caffeine — 3 to 5 cups per day — has also been associated with increased risk of cardiovascular disease.
Based purely on its composition, coffee should win hands down: a cup of tea has about half the dose (40 milligrams) of the stimulant caffeine that you would find in a standard cup of brewed filter coffee (80 to 115 milligrams).
Though tea is lower in caffeine, it's rich in L-theanine, a powerful antioxidant that also stimulates your brain ( 49 , 50 ). Unlike caffeine, L-theanine may provide anti-stress effects by increasing your brain's alpha waves, which help you calm down and relax ( 51 ).