What is it and how much is safe?
Caffeine is a bitter substance found in coffee, tea, soft drinks, energy drinks, chocolate, kola nuts and certain medicines. It has many effects on the body's metabolism, including stimulating the central nervous system. This can make you more alert and give you a boost of energy. Caffeine is one of the most widely used stimulants, and is generally considered safe at moderate levels of use: 300-400 mg of caffeine per day, or the amount in 3-4 cups of coffee.
As with most foods that don't contain essential nutrients, the key to caffeine intake is moderation.
Source: U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov .
Caffeine is also found in prescription and over-the-counter medicines where it is used to treat tiredness or drowsiness and to improve the effect of some pain relievers. The US Food and Drug Administration advises consumers avoid pure powdered caffeine, as this form of caffeine increases the chance of consuming a lethal dose. A single teaspoon of powdered caffeine is roughly equivalent to 28 cups of coffee.
Source: US Food and Drug Administration. Products and Ingredients: Pure and highly concentrated caffeine. Retrieved from www.fda.gov/food/dietarysupplements/productsingredients/ucm460095.htm
Caffeine is a diuretic
Caffeine is a diuretic. Research suggests that the diuretic action of caffeine is most relevant for those who do not regularly use caffeine. For people who have developed a tolerance to caffeine, its diuretic qualities are diminished, as are some of the other effects of caffeine. Doses of caffeine equivalent to the amount found in a typical cup of coffee or tea have limited diuretic activity.
Source: Maughan, R.J., Griffin, J. (2003) Caffeine ingestion and fluid balance: a review. Journal of Human Nutrition and Diet. Dec. 16 (6).
Got Sleep Deprivation?
The CDC says that students who are working or studying long hours may experience episodes of sleep deprivation. This can cause daytime sleepiness, sluggishness, and difficulty concentrating or making decisions. Teens and young adults who do not get enough sleep are at risk for problems, such as automobile crashes; poor grades and school performance; depressed moods; and problems with friends, fellow students and adult relationships.
You may think that if you can't sleep at night, you can just make up for it by drinking caffeine throughout the day. This is a common misconception. Drinking caffeine throughout the day could be what's causing your insomnia!
Too much caffeine can cause unpleasant side effects:
- Digestive problems
- Rapid heartbeat
- Muscle tremors
While many drinks and products containing caffeine have levels below the range that would have negative effects for most people, energy drinks can provide a wide range of caffeine in each drink. One energy drink may have 75 mgs of caffeine, which is the amount in a cup of coffee. Another may have 500 mgs of caffeine, which could put someone who hasn't built up a tolerance to caffeine into caffeine intoxication, resulting in nervousness, anxiety, restlessness, insomnia, nausea, vomiting, tremors and rapid heart rate.
Mixing alcohol and energy drinks
The Food and Drug Administration (FDA) reports that although there is little research on the effects of mixing caffeine and alcohol, several studies have suggested that people get more intoxicated and engage in riskier behavior when they drink the combination beverages than when they drink alcohol alone. Caffeine masks the effects of alcohol, tricking users into believing they can keep drinking well past the point of drunkenness. In November 2010, the FDA required several manufacturers of caffeinated alcoholic beverages to remove their products from the market.
Tolerance and Withdrawal
When people use caffeine every day, their bodies get used to it and they develop a tolerance. Some studies show that caffeine causes a physical dependence or addiction. If a person gets withdrawal symptoms when they suddenly stop using caffeine, then the person has a physical dependence on caffeine. Withdrawal symptoms can include: severe headaches, muscle aches, temporary feelings of depression and irritability.