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.
The body adapts by creating more adenosine receptors, so people who drink coffee every day still sleep normally. As a result, your energy levels drop and you need coffee just to combat withdrawal symptoms. Those symptoms can include irritability, headaches, and exhaustion.
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. However, there is wide variation in both how sensitive people are to the effects of caffeine and how fast they metabolize it (break it down).
Caffeine is well absorbed by the body, and the short-term effects are usually experienced between 5 and 30 minutes after having it. These effects can include increased breathing and heart rate, and increased mental alertness and physical energy. Depending on the individual, these effects can last up to 12 hours.
Research also shows that the changes in adenosine receptor levels typically reverse after a seven-day caffeine break. Think of it as a caffeine reset: By reducing your tolerance, you'll increase the boost you will feel when you start drinking coffee again.
Try not to consume caffeine two days in a row.
Going a day or two between each dose of caffeine can ensure that you get all of the benefits out of caffeine, without any of the withdrawal symptoms.
The Bottom Line
For healthy individuals, having a cup of coffee on an empty stomach is unlikely to cause any significant harm.
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.
Coffee is full of antioxidants, stimulants, and chlorogenic acids (powerful anti-inflammatory compounds) that make it an effective ingredient in the fight against acne. Coffee scrubs help get rid of dead skin cells, clear out pores, and may get rid of some strains of bacteria.
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. [2] Still, the cumulative research on coffee points in the direction of a health benefit.
Coffee Blocks the Effects of Adenosine
Caffeine can block the effects of adenosine, which is what makes you feel alert after your morning cup of joe. However, once the caffeine wears off, your body may experience a buildup of adenosine that hits you all at once, which is why coffee can make you feel tired.
Here are the boundaries. Healthy adults shouldn't consume more than 400 milligrams (mg) of caffeine per day. That's equal to about four 8-ounce cups of brewed coffee or 10 cans of cola. Teens should limit their caffeine intake to less than 100 mg per day (one 8-ounce cup of coffee or about two cans of cola).
Cut down slowly on the amount of caffeine in your diet. Don't make the mistake of stopping totally. You'll likely experience withdrawal symptoms and go back to drinking coffee or soda or taking a headache medication with caffeine in it to make the symptoms disappear. This starts the dependency cycle all over again.
As Parvinder Sagoo, Pharmacist and Online Health Adviser for SimplyMedsOnline, explains: “Drinking coffee as soon as you wake up could interfere with your body's cortisol production which could leave you feeling more stressed and anxious if you dive straight in for a coffee as oppose to a glass of water.”
For example, a cup of coffee to wake you up for work at 6 am. The caffeine crash usually comes into play about 3 to 4 hours after your first dose of caffeine. A caffeine crash can look a little like this: dozing off in the middle of the day, trouble focusing, feeling irritable, and overconsuming tiredness!
Drinking black coffee has numerous health benefits as it is loaded with antioxidants and nutrients. Let's have a look at some of the most important health benefits of drinking black coffee. Increasing age leads to decreased cognitive skills and increased risk of Dementia, Parkinson's and Alzheimer's disease.
The verdict: In terms of antioxidant content, blonde roasts are healthiest. Blonde Robusta coffee has the most antioxidants, followed closely by blonde and then medium-roast Arabica coffee.
When blood concentrations peak, you are likely to feel the characteristic effect of caffeine: a boost in energy. The reason for this phenomenon is that caffeine blocks specific receptors in the brain that mediate critical functions like sleep, arousal, cognition, memory, and learning.