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. Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks.
So how much coffee is the optimal amount to drink to get all the benefits, but avoid the negative side 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.
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.
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.
Drinking 2-3 Cups of Coffee a Day Can Lower Your Cardiovascular Disease Risk. A study has found a link between coffee drinking and longer life. It also found coffee was associated with a lower risk for cardiovascular disease. Two to three cups per day appeared to be the sweet spot for these benefits.
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.
Human response to coffee or caffeine can also vary substantially across individuals. Low to moderate doses of caffeine (50–300 mg) may cause increased alertness, energy, and ability to concentrate, while higher doses may have negative effects such as anxiety, restlessness, insomnia, and increased heart rate.
“Coffee can cause insomnia, nervousness, restlessness, upset stomach, nausea, and vomiting, increased heart rate and breathing rate, and other side effects,” Rissetto says. “Consuming large amounts of coffee might also cause headache, anxiety, agitation, ringing in the ears, and irregular heartbeat.”
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.
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.
The healthiest way to take your coffee is hot-brewed and black. One cup has virtually no calories or carbs, no fat, and is low in sodium. Black coffee also has micronutrients, including potassium, magnesium, and niacin.
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.
Thanks to the antioxidant-rich and anti-inflammatory flavonoids and polyphenols in coffee, it actually makes a wonderful skin-soother found in moisturizers and cleansers that reduces redness, inflammation, and helps protect against sun damage.
Another study, however, found that drinking at least two cups of coffee per day was associated with lower abdominal fat regardless of whether or not it was caffeinated coffee or decaffeinated.
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.
We typically start to feel the effects of our coffee's caffeine within 5-30 minutes of drinking it, and the effects can last for up to 12 hours. However, the effects we feel depend on many individual factors like our body mass, metabolism, and caffeine tolerance.
"If you regularly experience anxiety or panic attacks, you may want to consider avoiding or reducing your caffeinated coffee intake." Research from General Hospital Psychiatry found that higher levels of caffeine (around 5 cups of coffee per day) could potentially bring on panic attacks in those with existing anxiety.
When you start to look deeper, you will find other research that has shown that consuming caffeine throughout the day may actually result in weight gain, because caffeine affects cravings for food. Drinking caffeinated beverages, for example, may prompt you to eat more snacks and larger meals.
There's no clear link between caffeine intake and depression. However, caffeine intake and depression may be linked indirectly for people who are particularly sensitive to the effects of caffeine or who have too much caffeine. Caffeine can cause sleep problems that affect mood.
Heart health benefits
Coffee is full of health benefits. According to the American College of Cardiology, drinking two to three cups of coffee per day is associated with maintaining a healthy heart.
Caffeine affects the heart in multiple ways. Firstly, it promotes the release of noradrenaline and norepinephrine. Among other things, these hormones increase heart rate and blood pressure. Additionally, caffeine can act on enzymes that stimulate heart contractions, causing the heart to contract with more force.