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What Are The Health Benefits Of Caffeine?

Last updated Nov. 24, 2016

Approved by: Krish Tangella MD, MBA, FCAP

Caffeine is the most used drug in the world. For this reason caffeine, one of the most active ingredients in coffee has been studied extensively to help us understand how it affects our bodies. Caffeine can be found in a variety of sources, such as tea, cocoa, and cola drinks.

Human beings love their caffeine. In fact, caffeine is the most used drug in the world. For this reason, caffeine, one of the most active ingredients in coffee drinks, has been studied extensively to help us understand how it affects our bodies. Caffeine can also be found in a variety of sources such as tea, cocoa, and cola drinks.

For many individuals, coffee can one help stay awake and alert throughout the day. Caffeine is a stimulant that competes for the same protein spaces as a sleep-promoting chemical, known as adenosine. Caffeine also stimulates the heart and smooth muscles, increases stomach secretions, and promotes urination.

Research suggests that moderate amounts of caffeine affect the following behavior of adults:

  • Caffeine side effects include increasing alertness and reducing fatigue, which may be significant in low arousal situations (e.g. late night work shifts).
  • One of the benefits of caffeine is that it improves performance on attentiveness tasks and simple tasks that require a sustained response. These effects are often clearest with reduced alertness, although there is evidence that benefits may still occur when the person is unaffected. The effects on more challenging tasks are difficult to assess and most likely dependent on interactions between caffeine and other variables that increase alertness (e.g. personality and time of day).
  • Regular caffeine consumption appears to be beneficial, with higher users having better mental functioning.
  • Most individuals are experienced at controlling their caffeine consumption to maximize the above positive effects.
  • Caffeine use increases the metabolic rate

Too much caffeine can yield negative side effects including the following:

  • Caffeine can increase blood pressure in people who do not drink caffeinated drinks regularly. High blood pressure is directly correlated with an increase in strokes and brain disease, which increase the risk of dementia.
  • Caffeine may inhibit fine motor movement control (e.g. producing shaky hands).
  • It can increase the secretion of the stress hormone, cortisol.
  • Caffeine makes its users have difficulty falling or staying asleep.
  • It may be addictive and dependence can occur.
  • Postmenopausal women may suffer from accelerated bone loss with high caffeine consumption.
  • Other short-term side effects include headache, nausea, and anxiety.

Short-term overdose of caffeine is usually an excess of approximately 300 milligrams depending on body weight and level of caffeine tolerance. An overdose can result in a state of central nervous system over-stimulation, called caffeine intoxication or "caffeine jitters". The American Academy of Pediatrics recommends that adolescents consume less than 100 milligrams of caffeine a day. Younger children should not drink any caffeinated beverages on a regular basis.

The following is an example list of drinks that contain caffeine:

 Drink Quantity Caffeine
 Brewed 8 oz. (237 mL) 95-200 mg
 Brewed, defcaffeinated 8 oz. (237 mL) 2-12 mg
 Brewed, single-serve varieties 8 oz. (237 mL) 75-150 mg
 Brewed, single-serve varieties decaffeinated 8 oz. (237 mL) 2-4 mg
 Espresso, restaurant-style 1 oz. (30 mL) 47-75 mg
 Instant 8 oz. (237 mL) 27-173 mg
 Black tea 8 oz. (237 mL) 14-70 mg
 Black tea, decaffeinated 8 oz. (237 mL) 0-12 mg
 Green-tea 8 oz. (237 mL) 24-45 mg
 Coca-Cola 12 oz. (355 mL) 23-35 mg
 Diet Coke 12 oz. (355 mL) 23-47 mg
 Diet Pepsi 12 oz. (355 mL) 27-37 mg
 Dr. Pepper, regular and diet 12 oz. (355 mL) 36-42 mg
 Pepsi12 oz. (355 mL)  32-39 mg
 Sierra Mist, regular and diet 12 oz. (355 mL) 0 mg
 Sprite, regular and diet 12 oz. (355 mL) 0 mg

Additional Resources:

Acheson, K. J., Zahorska-Markiewicz, B., Pittet, P. H., Anantharaman, K., & Jequier, E. (1980). Caffeine and coffee: their influence on metabolic rate and substrate utilization in normal weight and obese individuals. The American journal of clinical nutrition, 33(5), 989-997.

Adapted from Journal of Food Science, 2010; Pediatrics, 2011; USDA National Nutrient Database for Standard Reference, Release 26; Journal of Food Science, 2007; Journal of Analytical Toxicology, 2006; Pepsico, 2014; Coca-Cola, 2014; Dr Pepper, 2014; A&W Root Beer; 7UP

American Academy of Pediatrics Committee on Nutrition and the Council on Sports Medicine and Fitness. Sports drinks and energy drinks for children and adolescents: Are they appropriate? Pediatrics. 2011;127:1182.

Brice, C. F., & Smith, A. P. (2002). Effects of caffeine on mood and performance: a study of realistic consumption. Psychopharmacology, 164(2), 188-192.

Chin JM, et al. Caffeine content of brewed teas. Journal of Analytical Toxicology. 2008;32:702.

Coffee drinking tied to lower risk of suicide. (n.d.). Retrieved December 2, 2014, from http://news.harvard.edu/gazette/story/2013/07/drinking-coffee-may-reduce-risk-of-suicide-by-50/

Dulloo, A. G., Geissler, C. A., Horton, T., Collins, A., & Miller, D. S. (1989). Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers. The American journal of clinical nutrition, 49(1), 44-50.

Fredholm, B. B. (1995). Adenosine, Adenosine Receptors and the Actions of Caffeine*. Pharmacology & toxicology, 76(2), 93-101.

Fukushima, Y., Ohie, T., Yonekawa, Y., Yonemoto, K., Aizawa, H., Mori, Y., ... & Kondo, K. (2009). Coffee and green tea as a large source of antioxidant polyphenols in the Japanese population. Journal of agricultural and food chemistry, 57(4), 1253-1259.

Hindmarch, I., Rigney, U., Stanley, N., Quinlan, P., Rycroft, J., & Lane, J. (2000). A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality.Psychopharmacology, 149(3), 203-216.

Lieberman, H. R., Wurtman, R. J., Emde, G. G., Roberts, C., & Coviella, I. L. G. (1987). The effects of low doses of caffeine on human performance and mood.Psychopharmacology, 92(3), 308-312.

Lovallo, W. R., Whitsett, T. L., al'Absi, M., Sung, B. H., Vincent, A. S., & Wilson, M. F. (2005). Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels. Psychosomatic medicine, 67(5), 734.

McCusker RR, et al. Caffeine content of decaffeinated coffees. Journal of Analytical Toxicology. 2006;30:611.

Milon, H., Guidoux, R., & Antonioli, J. A. (1988). Physiological effects of coffee and its components. Coffee. London: Elsevier Applied Science, 3, 81-124.

Nehlig, A., Daval, J. L., & Debry, G. (1992). Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Research Reviews, 17(2), 139-170.

Rapuri, P. B., Gallagher, J. C., Kinyamu, H. K., & Ryschon, K. L. (2001). Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes. The American journal of clinical nutrition,74(5), 694-700.

Ruxton, C. H. S. (2008). The impact of caffeine on mood, cognitive function, performance and hydration: a review of benefits and risks. Nutrition Bulletin,33(1), 15-25.

Seifert SM, et al. Health effects of energy drinks on children, adolescents, and young adults. Pediatrics. 2011;127:511.

Shapiro, R. E. (2007). Caffeine and headaches. Neurological Sciences, 28(2), S179-S183.

Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40(9), 1243-1255.

Smith, A. P., Brockman, P., Flynn, R., Maben, A., & Thomas, M. (1993). Investigation of the effects of coffee on alertness and performance during the day and night. Neuropsychobiology, 27(4), 217-223.

USDA National Nutrient Database for Standard Reference, Release 26. U.S. Department of Agriculture, Agricultural Research Service. http://ndb.nal.usda.gov. (accessed Jan. 9, 2014)

Helpful Peer-Reviewed Medical Articles:

Frary, C. D., Johnson, R. K., & Wang, M. Q. (2005). Food sources and intakes of caffeine in the diets of persons in the United States. Journal of the American Dietetic Association, 105(1), 110-113.

Graham, T. E. (2001). Caffeine and exercise. Sports medicine, 31(11), 785-807.

Nawrot, P., Jordan, S., Eastwood, J., Rotstein, J., Hugenholtz, A., & Feeley, M. (2003). Effects of caffeine on human health. Food Additives & Contaminants, 20(1), 1-30.

Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40(9), 1243-1255.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Nov. 24, 2016
Last updated: Nov. 24, 2016