Caffeine is a stimulant naturally found in beverages such as coffee and tea. It is also added to other beverages such as energy drinks and soda.
Caffeine increases chemicals in the brain that improve mood, combat fatigue and enhance concentration.
For this reason, many people choose to drink caffeinated beverages to start their day or recover from an afternoon crash.
However, it is thought that the stimulating effects of caffeine become less pronounced over time, as your body becomes tolerant or less responsive to its effects.
This article explains how caffeine produces its stimulating effects and whether it is possible to develop caffeine tolerance.
How caffeine tolerance develops
Caffeine works primarily by blocking the brain's adenosine receptors, which play a role in sleep, arousal and cognition.
A molecule called adenosine normally binds to these receptors, inhibiting the release of brain chemicals such as dopamine that increase arousal and promote wakefulness.
By blocking adenosine from binding to its receptors, caffeine increases the release of these stimulating brain chemicals, thereby reducing fatigue and increasing alertness.
One study showed that high doses of caffeine can block up to 50% of adenosine receptors in the brain.
The stimulating effects of caffeine occur within 30-60 minutes of ingesting the substance and last on average 3-5 hours.
However, according to a seminal study from the 1980s, regular caffeine intake increases the body's production of adenosine receptors, thereby increasing the likelihood of adenosine binding to these receptors.
Therefore, this reduces the effects of caffeine, allowing you to become tolerant to it over time.
Caffeine tolerance exists
Caffeine tolerance occurs when the effects of caffeine diminish over time with regular ingestion.
Tolerance to the effects of caffeine has been demonstrated on blood pressure, exercise performance, mental alertness, and performance.
blood pressure and heart rate
Caffeine can increase blood pressure in the short term, but regular caffeine intake quickly develops tolerance to this effect .
In a 20-day study, 11 low-caffeine drinkers took a daily pill containing 1.4 mg of caffeine per pound of body weight (3 mg per kilogram of body weight) or a placebo.
For a 150-pound (68-kilogram) person, this amount is equivalent to about 200 milligrams of caffeine, or two 8-ounce (240-ml) cups of coffee.
Caffeine significantly increased blood pressure compared with placebo, but the effect wore off after eight days. Caffeine does not affect heart rate.
Studies have shown that caffeine does not cause further increases in blood pressure in people with high blood pressure who regularly consume caffeine.
sports performance
Multiple studies have shown that caffeine can improve muscle strength and power and delay fatigue through exercise.
However, these performance benefits may decrease with regular caffeine intake.
In a 20-day study, 11 low-caffeine drinkers took a daily pill of 1.4 mg of caffeine per pound of body weight (3 mg per kilogram of body weight) or a placebo.
Compared to placebo, daily caffeine intake increased riding power by 4-5% during the first 15 days of 2 exercise tests, but performance effects declined thereafter.
After 15 days, participants who took caffeine continued to experience greater performance improvements than those who took placebo, but performance gradually declined thereafter, indicating a gradual but partial tolerance to the effects of caffeine.
mental alertness and performance
Caffeine's stimulant effects have been shown to enhance mental alertness and performance, especially in people who don't consume caffeine regularly.
Among regular caffeine drinkers, the often reported improvements in mental alertness and performance are related more to reversal of caffeine withdrawal symptoms than to enhancement compared with normal states.
With a daily dose of 100 mg (equivalent to an 8-ounce (240 ml) cup of coffee), you can develop a caffeine dependence in just 3 days.
Caffeine withdrawal symptoms include drowsiness, difficulty concentrating, and headaches. They appear after 12-16 hours without caffeine and peak around 24-48 hours.
How to Overcome Caffeine Tolerance
You can overcome tolerance to the effects of caffeine by consuming less caffeine or consuming it less frequently.
Consuming more caffeine than usual can also help you overcome your tolerance in the short term.
In one study, researchers examined the effects of caffeine on self-reported mood and cognition in 17 daily coffee drinkers.
Participants were asked to either drink coffee as usual or go without coffee for 30 hours before taking a pill containing 250 milligrams of caffeine or a placebo.
Caffeine improved attention and memory compared to a placebo, even if participants didn't quit coffee, suggesting that for daily coffee drinkers, drinking more coffee than usual may have some benefits.
In either case, it is not recommended to continually increase your caffeine intake in order to obtain greater benefits. This can be dangerous, and there is a limit to the effects of caffeine, as taking more does not always lead to greater benefits.
How much caffeine is safe?
Research shows that healthy adults can safely consume up to 400 mg of caffeine per day.
Pregnant women should not consume more than 200 milligrams of caffeine per day, with some studies recommending an upper limit of 300 milligrams per day.
For reference, here's a list of popular caffeinated drinks and their caffeine content:
- Coffee: 96 mg per 1 cup (8 ounces or 240 ml)
- Standard energy drink: 72 mg per 1 cup (8 oz or 240 ml)
- Green tea: 29 mg per 1 cup (8 oz 240 ml)
- Soft drinks: 34 mg per 1 can (12 oz or 355 ml)
Recommendations for safe caffeine intake include all sources of caffeine.
Keep in mind that many dietary supplements, such as pre-workout supplements and fat burners, as well as some over-the-counter pain relievers, such as Excedrin or Midol, contain caffeine.
The caffeine in these products may be synthetically produced or may come from natural sources such as green coffee beans, guarana, or yerba mate.
Dark chocolate contains 16 milligrams per ounce (28 grams) and may also be a significant source of caffeine when consumed in large amounts.
generalize
Many people drink caffeinated beverages such as coffee, tea, and soft drinks to stay awake.
Regular consumption of these beverages increases adenosine receptors in the brain, allowing more adenosine molecules to bind to them. Over time, this can improve the body's tolerance to caffeine's stimulating effects.
You can reduce your tolerance to caffeine by reducing your daily intake or consuming it less frequently, such as once or twice a week instead of once a day.
Increasing your daily caffeine intake above normal can also reduce tolerance in the short term, but is not recommended.
