Is caffeine bad for you

Is caffeine bad for you?

Pawel Malczewski
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Summary

The positive or negative effects of caffeine on health mainly depend on the individual’s genetic predisposition.

The majority of the population can handle moderate amounts of caffeine very well (around 400ml) and can enjoy its health benefits with only a few minor negative effects.

However, in some cases the effects of caffeine on the body and health can be more negative than positive, depending on factors such as caffeine sensitivity level, over-consumption, possible allergy or the presence of certain diseases. For a quick answer click here.

Explanation

Since there is no definitive answer to the question of whether caffeine is bad or good for you, you should read the following and assess what scenario applies to your case.

Caffeine levels in drinks and food

Caffeine is a naturally occurring substance in fruits and the leaves of plants such as coffee, tea, yerba mate and guarana. It is present in many products including sodas, energy drinks, chocolate bars, cough syrups and slimming tablets.

Caffeine is also added to some over-the-counter medicines such as cold medications. Caffeine contents in drinks and foods may range anywhere from trace amounts in decaffeinated drinks such as coffee or tea to over 300mg per serving in products such as energy drinks or Starbucks coffee.

For the full list of contents of caffeine in drinks please see “Caffeine levels in drinks and foods”

Is caffeine a drug?

Caffeine is a stimulant drug (known as a psychoactive drug) that affects the nervous system, causing symptoms such as alertness and temporary mood elevation. It also affects the rest of the body such as the hormonal system and the metabolism of fat during exercise (although studies showing long term weight-loss effects are inconclusive). (1)Fredholm BB, Battig K, Holmén J, Nehlig A, Zvartau EE. Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use. Pharmacological Reviews March 1, 1999 vol. 51 no. 1 83-133. Available here.

Caffeine is a dose-dependent drug. The larger the dose, the stronger the stimulation effects. However, it doesn’t collect in the body, but gets broken down in the liver and excreted through urine. (2)MedlinePlus. Caffeine in the diet. U.S. National Library of Medicine. National Institutes of Health. Available here.

Caffeine reaches the bloodstream in about 15 minutes, attaining its peak saturation in the blood in 15-45 minutes. It has a half-life of around 6 hours (the time taken for the caffeine concentration in your blood to reduce by half). (3)Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992 May-Aug;17(2):139-70. Available here.

Although a drug, caffeine is not addictive like other drugs. Nevertheless, individuals who drink caffeine daily develop a physical dependence to it. (read more..)

How does caffeine affect your body if you are allergic, sensitive or caffeine-naive?

The way you handle caffeine and the intensity of the symptoms depend on a variety of factors, such as the individual’s sensitivity and tolerance level to caffeine, and in rare cases caffeine allergy.

In other words, the positive and/or negative effects that caffeine exerts on each person and if one should drink caffeinated drinks and in what quantities are closely correlated to:

  • Caffeine allergy
    Caffeine allergy is extremely rare, with only a handful of cases recorded. However, if you show common allergic reactions to caffeine such as hives or anaphylaxis, you should avoid any amount of caffeine. (read more..)
  • Caffeine sensitivity
    The bottom line is, are you a fast or a slow caffeine metabolizer?

    Caffeine sensitivity is an important factor that determines whether coffee is good or bad for you. The genetic make-up dictates how many caffeine-breaking enzymes are produced by the body, therefore influencing how well you can handle caffeine.

    Being caffeine-sensitive or a slow caffeine metabolizer restricts how much coffee you can manage, by producing unpleasant overdose symptoms as soon as you surpass your caffeine limit. Negative rather than positive health effects are likely to occur as a result of caffeine intake. The more caffeine sensitive you are, the less caffeine you are able to consume before you experience the negative effects. In extreme cases, if you are very sensitive, you may not be capable of having any caffeinated drinks. (read more..)

    Fast caffeine metabolizers, on the other hand, can quickly break down and excrete caffeine. They normally experience a wide range of health benefits of caffeine intake, as mentioned in the section below. The main point is that, if you are sensitive to caffeine, drinking caffeinated beverages will bring you more negative than positive effects, depending on the sensitivity level and on the amount consumed. However, if you are a fast metabolizer, the positive effects of caffeine intake described below may be applicable.

    NOTE: many studies on caffeine don’t take into consideration genetic factors.

    You are not sensitive to caffeine. In this case, you may build your tolerance to the point of over-consumption and high dependency (caffeinism), which has detrimental results on your health. Studies don’t show any health benefits from such high amounts of caffeine.

    NOTE: many studies don’t take into consideration the tolerance factor, making the results misleading. For instance, we cannot conclude that energy drinks’ containing caffeine, have a diuretic effect if we don’t know if the participants are usual consumers of caffeinated drinks. Their increased urination may be due to the fact that they haven’t developed a tolerance to caffeine rather than caffeine having a diuretic effect.

Negative effects of caffeine

Negative health consequences (often leading to serious medical conditions) are associated with caffeinism, high sensitivity, overdose or allergy to caffeine as described in the section above. Learn your limits of caffeine intake to avoid potentially dangerous outcomes.

  • Caffeine and GERD (gastroesophageal reflux disease)
    In people who suffer from GERD, or peptic ulcer, caffeinated coffee has shown to worsen these conditions more significantly than decaffeinated coffee. It is advisable for GERD sufferers to avoid caffeinated drinks, especially coffee. (4)Wendl B, Pfeiffer A, Pehl C, Schmidt T, Kaess H. Effect of decaffeination of coffee or tea on gastro-oesophageal reflux. Aliment Pharmacol Ther. 1994 Jun;8(3):283-7. Available here. (5)Nwokediuko SC. Current Trends in the Management of Gastroesophageal Reflux Disease: A Review. ISRN Gastroenterology. Volume 2012 (2012), Article ID 391631, 11 pages. Available here. (6)Drugs. Caffeine. Available here.
  • Caffeine and blood pressure
    Caffeine raises blood pressure when the tolerance to caffeine is not complete. If caffeine is taken after a period of abstinence, individuals experience a slight rise in blood pressure. However, this increase in blood pressure is reduced or totally disappears with continuous caffeine intake of the same dosage.

    For individuals with a moderate to high caffeine intake, half of them will build tolerance to caffeine within 5 days and their blood pressure will return to normal. The other half, on the other hand, will continue with slightly elevated blood pressure, even if they are used to consume a moderate to high amount of caffeine daily.

    The increase in blood pressure is small, of about around 3mm Hg. Nevertheless, these changes may negatively affect individuals at high risk of cardiovascular diseases. Regular caffeine intake by people prone to hypertension may be harmful and is not advisable.

    The effects of caffeine on the cardiovascular system is thought to be due to the blocking of adenosine receptors and the inhibition of phosphodiesterases. (7)Lovallo WR, Wilson MF, Vincent AS, Sung BH, McKey BS, Whitsett TL. Blood Pressure Response to Caffeine Shows Incomplete Tolerance After Short-Term Regular Consumption. Hypertension.2004; 43: 760-765. Available here. (8)Nurminen ML, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. November 1999, Volume 53, Number 11, Pages 831-839. Available here.

  • Caffeine and heart health
    Studies show quite different health effects of caffeine on the heart health depending on if you are a slow or a fast metabolizer.

    Slow metabolizers have an increased risk of non-fatal heart attack, if they drink 2-3 cups of coffee daily (200-300mg caffeine). Additionally, those who drink 4 cups of coffee per day have a four time greater chance of having a heart attack compared with those who drink about one cup (100mg caffeine) per day. (read more..)

    For fast metabolizers, on the other hand, caffeine improves heart health and reduces the risk of heart attack. See the section for the health benefits of caffeine below.

  • Caffeine and anxiety
    Dependence on caffeine, having an overdose of caffeine or stopping caffeine intake after long term use may induce symptoms of anxiety. (9)Heckman MA, Weil J, De Mejia EG. Caffeine (1, 3, 7-trimethylxanthine) in Foods: A Comprehensive Review on Consumption, Functionality, Safety, and Regulatory Matters. Journal of Food Science. Volume 75, Issue 3, pages R77–R87, April 2010. Available here.
  • Caffeine and dehydration
    Caffeine as a drug has diuretic properties. When taken in high amounts, especially in a tablet form (not as a caffeinated drink), it causes the kidneys to increase the production of urine. High doses of more than 360mg of caffeine increase urine production. (10)Passmore AP, Kondowe GB, Johnston GD. Renal and cardiovascular effects of caffeine: a dose-response study. Clin Sci (Lond). 1987 Jun;72(6):749-56. Available here.

    However, when taken as coffee, tea, or other caffeinated drinks, such as soda or energy drinks, the contribution of the liquid negates the diuretic effects of caffeine. Caffeinated drinks can, therefore, be considered as being hydrating.

    For most individuals, the diuretic effects of caffeine get reduced or completely disappear with the increased tolerance to caffeine (within 1-5 days). This means that after a period of caffeine abstinence, a dose of caffeine may cause various effects on the body, including increased urination, but after becoming accustomed to the regular caffeine intake, these symptoms disappear. (Read more..) (11)Killer SC, Blannin AK, Jeukendrup AE. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS One. 2014 Jan 9;9(1):e84154. Available here.

    If caffeine is consumed before exercise, its’ diuretic properties  are negated compared to having caffeine followed by rest.

    Please be aware that some studies that have shown the diuretic effects of energy drinks didn’t take into account the caffeine tolerance factor and, therefore, are flawed.

    In summary:

  1. consuming caffeine without liquid may cause more urination;
  2. regular caffeine users have minimal or no effect on urination;
  3. caffeine before exercise doesn’t cause increased urination;
  4. you may urinate more after a caffeinated drink if you are already well hydrated.
  • Caffeine and sleep (especially if consumed in the afternoon)
    Caffeine can affect sleep quality. Around 90% of the adult population in United States consumes caffeine in the afternoon (between noon and 6pm), and 68.5% in the evening (6pm-midnight). On average, adults consume about 329 mg (+- 180mg) of caffeine per day.

    Generally, for moderate caffeine users (400mg of caffeine/day) the sleep disturbances (poor sleep quality, reduced sleep time, time taken to fall asleep and sleep efficiency) occur with a dosage consumed up to 6 hours before sleep time.

    Therefore, it is recommended to abstain from caffeinated drinks for a minimum of 6 hours before sleep time (on average, it should be avoided after 5pm). (12)Drake C, Roehrs T, Shambroom J, Roth T. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to bed. Sleep Disorders & Research Center, Henry Ford Hospital, Detroit, Department of Psychiatry and Behavioral Neurosciences, Wayne State College of Medicine, Detroit. Available here. (13)Clark I, Landolt HP. Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials. Science Direct 01/2016. Available here.

  • Caffeine intake may increase the risk of infertility and miscarriage
    Overall, current guidelines recommend limiting caffeine consumption to a maximum of 200mg daily (e.g. 2 coffees). (14)Drugs. Caffeine. Available here. However, it may vary between individuals and in some cases 200mg per day may be too much.

    Caffeine rapidly crosses the human placenta and reaches a similar concentration in the fetus. (15)Batta A, Kaur H. Coffee is a medical advice. Dept of Medica Biochemistry, Baba Farid University of Health Sciences/GGS Medical College Faridkot, Punjab, India. Feb 2016. Available here.

    If you are a slow metabolizer and consume 2-3 coffees per day, the risk of infertility and miscarriage increases. (16)Chen LW, Wua Y, Neelakantana N, Foong-Fong Chong M, Pan A, van Dam RM. Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose–response meta-analysis of prospective studies. Public Health Nutrition / Volume 19 / Issue 07 / May 2016, pp 1233-1244. Available here. An increase of 100mg of caffeine intake per day (equivalent to 1 cup of coffee) is associated with a 7% higher risk of loss of pregnancy (17)Chen LW, Wua Y, Neelakantana N, Foong-Fong Chong M, Pan A, van Dam RM. Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose–response meta-analysis of prospective studies. Public Health Nutrition / Volume 19 / Issue 07 / May 2016, pp 1233-1244. Available here., and a 13% higher risk of a lower birth rate. (18)Chen LW, Wua Y, Neelakantana N, Foong-Fong Chong M, Pan A, van Dam RM. Maternal caffeine intake during pregnancy is associated with risk of low birth weight: a systematic review and dose-response meta-analysis. BMC Medicine201412:174. Available here.

    One study showed that an amount of caffeine below 300 mg per day (around 1-2 coffees or 4 cups of tea) doesn’t increase the risk of spontaneous abortion or pregnancy complications, reduce fertility, or have an adverse neurodevelopmental effect. However, this study doesn’t take into account the caffeine sensitivity aspect, which means that its results may be not applicable to slow metabolizers.

    Studies on infertility show that large amounts of caffeine may increase the risk of infertility. Small amounts of caffeine, however, have no impact. Therefore, when planning to get pregnant is recommended decrease the caffeine intaketo no more than 300mg per day. (19)Morgan S, Koren G, Bozzo P. Is caffeine consumption safe during pregnancy? Canadian Family Physician April 2013 vol. 59 no. 4 361-362. Available here. (20)Heckman MA, Weil J, De Mejia EG. Caffeine (1, 3, 7-trimethylxanthine) in Foods: A Comprehensive Review on Consumption, Functionality, Safety, and Regulatory Matters. Journal of Food Science. Volume 75, Issue 3, pages R77–R87, April 2010. Available here.

  • Caffeine and Fibrocystic Breast Disease
    Caffeine consumption has been associated with a higher risk of fibrocystic breast disease in women. The association was the highest in women who had a higher risk of developing breast cancer.

    Daily caffeine amounts of between 31 and 250 mg increase the risk by 1.5 times and amounts over 500 mg by 2.3 times. (21)Boyle CA, Berkowitz GS, LiVolsi VA, Ort S, Merino MJ, White C, Kelsey JL. Caffeine Consumption and Fibrocystic Breast Disease: A Case-Control Epidemiologic Study. JNCI J Natl Cancer Inst (1984) 72 (5): 1015-1019. Available here.

  • Caffeine and indigestion
    Caffeine intake by obese individuals is associated with indigestion. (22)Shirlow MJ, Mathers CD. A Study of Caffeine Consumption and Symptoms: Indigestion, Palpitations, Tremor, Headache and Insomnia. Int. J. Epidemiol. (1985) 14 (2): 239-248. Available here. 
  • Caffeine and insulin sensitivity
    Caffeine consumption can decrease glucose uptake and insulin sensitivity. (23)Keijzers GB, de Galan BE, Tack CJ, Smits P. Caffeine Can Decrease Insulin Sensitivity in Humans. doi: 10.2337/diacare.25.2.364 Diabetes Care February 2002 vol. 25 no. 2 364-369. Available here. (24)Greer F, Hudson 2, Ross R, Graham T. Caffeine Ingestion Decreases Glucose Disposal During a Hyperinsulinemic-Euglycemic Clamp in Sedentary Humans. Diabetes 2001 Oct; 50(10): 2349-2354. Available here.
  • Caffeine and menopause
    Caffeine use is associated with greater vasomotor symptom bother (e.g. hot flashes and night sweats) in postmenopausal women. (25)Faubion SS, Sood R, Thielen J, Shuster LT. Caffeine and menopausal symptoms: what is the association? Menopause:February 2015 – Volume 22 – Issue 2 – p 155–158. Available here.
  • Caffeine and seizure disorders
    Caffeine supplements may lower the seizure threshold in individuals with seizure disorders which means that it may induce new seizure occurrences. (26)Drugs. Caffeine. Available here.
  • Caffeine medication contraindications
    Caffeine increases the activity of a so called hepatic cytochrome P450 (CYP)1A2.  It can be thought of as a group of enzymes that break down not only caffeine or alcohol but also various medications. This means that an increased activity of CYP1A2 may impact the potency of some medications.

    Other medications may reduce the activity of CYP1A2 and, therefore, reduce the break-down and elimination of caffeine, causing adverse health effects from an excess of caffeine. (27)Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet. 2000 Aug;39(2):127-53. Available here. (28)Faber MS, Fuhr U. Time response of cytochrome P450 1A2 activity on cessation of heavy smoking. Clin Pharmacol Ther. 2004 Aug;76(2):178-84. Available here.

    Consult your doctor about the amount of caffeine you should be consuming daily when on medication.

The caffeine intake may additionally lead to:

  • Caffeine overdose
    You can have a caffeine overdose, regardless of whether you are sensitive to caffeine or not. This depends on the combination of the caffeine dose and your level of sensitivity.

    You can be extremely sensitive to caffeine and a few sips can be enough to cause the onset of symptoms or you can handle caffeine very well and 5 coffee shots in one go might not affect you. To avoid caffeine overdose, learn your safe limit.

Health benefits of caffeine – when is caffeine good for you?

Most of the caffeine health benefits are experienced by people who are not allergic or sensitive to caffeine and don’t consume excessive amounts or overdose on caffeine.

  • Caffeine and cognitive function and psycho-motor performance
    Caffeinated beverages, such as coffee or tea, if consumed throughout the day, improve alertness, learning capacity, mood, memory and psychomotor performance. These results refer to medium to high caffeine users, rather to low caffeine users.

    Please note that low caffeine users may be sensitive to it and, therefore, be affected negatively by caffeine intake through anxiety, jitteriness and reduced quality of sleep. (29)Hindmarch I, Rigney U, Stanley N, Quinlan P, Rycroft J, Lane J. A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology (Berl). 2000 Apr;149(3):203-16. Available here. (30)Rogers PJ, Heatherley SV, Mullings EL, Smith JE. Faster but not smarter: effects of caffeine and caffeine withdrawal on alertness and performance. Psychopharmacology. March 2013, Volume 226, Issue 2, pp 229-240. Available here.

  • Caffeine and weight loss
    Caffeine exerts some weight reducing effects in the short term, by increasing the rate of burning fat and boosting the metabolic rate.

    However, in the long term, these effects are negligible due to the increased tolerance to caffeine. Nevertheless, it may be positive as a tablet or powder when taken before exercise to help increase the burning of the fatty tissue. (read more..)

  • Caffeine and Gout
    Long term caffeine consumption is associated with decreased risk of gout. (31)Choi HK, Willett W. Curhan G. Coffee consumption and risk of incident gout in men: A prospective study. http://onlinelibrary.wiley.com/doi/10.1002/art.22712/full Available here.
  • Caffeine and heart health
    As explained above, there are distinct health effects of caffeine on heart health depending if you are a slow or fast metabolizer. Heart health benefits of caffeine only apply to fast metabolizers.

    For medium to high caffeine users, those that can handle larger amounts of caffeine, or fast metabolizers, long term caffeine intake, of about 400mg of caffeine (between 3-5 cups of coffee daily), shows the largest reduction on cardiovascular disease risk. For this group, there is a 22% lower risk of heart attack by having 200-300mg caffeine per day (2-3 cups of coffee).

    The risk doesn’t increase even with larger amounts of coffee. (32)Ding M, Bhupathiraju SN, Satija A, van Dam RM, Hu FB. Long-Term Coffee Consumption and Risk of Cardiovascular Disease: A Systematic Review and a Dose-Response Meta-Analysis of Prospective Cohort Studies. CIRCULATIONAHA.113.005925. November 7, 2013. Available here. (33)Crippa A, Discacciati A, Larsson SC, Wolk A, Orsini N. Coffee Consumption and Mortality From All Causes, Cardiovascular Disease, and Cancer: A Dose-Response Meta-Analysis. Am J Epidemiol. 2014 Oct 15;180(8):763-75. Available here.

    To see the effects of caffeine on slow metabolizers, please see the above section listing negative effects.

  • Caffeine and skin cancer
    Two recent, large studies on the effects of coffee on skin cancer have found that caffeinated coffee consumption is associated with a reduction of a risk of malignant melanoma by up to 25%. Because decaffeinated coffee didn’t show a significant association with the risk of melanoma, scientists think that this may be due to caffeine. More studies on caffeine are planned to confirm these theories. (34)Loftfield E, Freedman ND, Graubard BI, Hollenbeck AR, Shebl FM, Mayne ST, Sinha R. Coffee drinking and cutaneous melanoma risk in the NIH-AARP diet and health study. J Natl Cancer Inst. 2015 Jan 20;107(2). pii: dju421. Available here. (35)Liu J, Shen B, Shi M, Cai J. Higher Caffeinated Coffee Intake Is Associated with Reduced Malignant Melanoma Risk: A Meta-Analysis Study. Available here.
  • Caffeine and depression
    Several observational studies show that higher caffeine users (especially in coffee) have a decreased risk of depression and depression related suicides. An amount of caffeine of about 400mg (equivalent to 4-5 coffees) is the most optimal in risk reduction and is associated with 20% lower risk of developing depression and 53% lower suicide risk.

    However, the risk increases with a usage of 800mg of caffeine per day or more (at least 8 cups of coffee per day) (36)Lucas M, Mirzaei F, Pan A, Okereke OI, Willett WC, O’Reilly ÉJ, Koenen K, Ascherio A. Coffee, Caffeine, and Risk of Depression Among Women. Arch Intern Med. 2011 Sep 26; 171(17): 1571–1578. Available here. (37)Tanskanen A, Tuomilehto J, Viinamäki H, Vartiainen E, Lehtonen J, Puska P. Heavy coffee drinking and the risk of suicide. Eur J Epidemiol. 2000;16(9):789-91. Available here. (38)Kawachi I, Willett WC, Colditz GA, Stampfer MJ, Speizer FE. A Prospective Study of Coffee Drinking and Suicide in Women. Arch Intern Med. 1996;156(5):521-525. Available here. (39)Lucas M, O’Reilly EJ, Pan A, Mirzaei F, Willett WC, Okereke OI, Ascherio A. Coffee, caffeine, and risk of completed suicide: Results from three prospective cohorts of American adults. The World Journal of Biological Psychiatry. Volume 15, Issue 5, 2014. Available here.
    .

  • Caffeine and Alzheimer’s Disease
    Caffeine consumption has been shown to reduce the risk of developing Alzheimer’s disease. (40)Santos C, Costa J, Santos J, Vaz-Carneiro A, Lunet N. Caffeine Intake and Dementia: Systematic Review and Meta-Analysis. Journal of Alzheimer’s Disease, vol. 20, no. S1, pp. 187-204, 2010. Available here. (41)Eskelinen MH, Kivipelto Miia. Caffeine as a Protective Factor in Dementia and Alzheimer’s Disease. Journal of Alzheimer’s Disease, vol. 20, no. S1, pp. 167-174, 2010. Available here. (42)Rosso A. Review: Caffeine: Neuroprotective Functions in Cognition and Alzheimer’s Disease. AM J ALZHEIMERS DIS OTHER DEMEN October/November 2008 23: 417-422. Available here.
  • Caffeine and Parkinson’s
    Caffeinated coffee drinkers have a 31% decreased risk of developing Parkinson’ disease. (43)Rodrigues F, Caldeira D, Ferreira J, Costa J. Caffeine exposure and the risk of Parkinson’s disease: an update of a systematic review and meta-analysis of observational studies. Instituto de Medicina Molecular, Clinical Pharmacology Unit, Lisbon, Portugal. Available here. (44)Santos C, Costa J, Santos J, Vaz-Carneiro A, Lunet N. Caffeine Exposure and the Risk of Parkinson’s Disease: A Systematic Review and Meta-Analysis of Observational Studiess. Journal of Alzheimer’s Disease, vol. 20, no. S1, pp. 221-238, 2010. Available here. (45)Ascherio A, Weisskopf MG, O’Reilly EJ, McCullough ML, Calle EE, Rodriguez C, Thun MJ. Disease Mortality in the Cancer Prevention Study II Cohort: The Modifying Effects of Estrogen. Am. J. Epidemiol. (2004) 160 (10): 977-984. Available here. (46)Hernán MA, Takkouche B, Caamaño-Isorna F, Gestal-Otero JJ. A meta-analysis of coffee drinking, cigarette smoking, and the risk of Parkinson’s disease. Ann Neurol. 2002 Sep;52(3):276-84. Available here.
  • Caffeine and dementia
    Caffeine intake reduces the risk of developing dementia. Scientists believed that factors responsible for this reduction may be due to caffeine, antioxidant capacity and increase of insulin sensitivity. (47)Eskelinen MH, Kivipelto Miia. Caffeine as a Protective Factor in Dementia and Alzheimer’s Disease. Journal of Alzheimer’s Disease, vol. 20, no. S1, pp. 167-174, 2010. Available here. (48)Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC Public Health 2014. Available here.
  • Caffeine and multiple sclerosis (MS)
    Studies on the association of caffeine and MS are still inconclusive. Some observational studies show no association, while the most recent study, from 2016, found a correlation between high consumption of caffeinated coffee and about 30% of decreased risk of multiple sclerosis.

    This is thought to be due to the caffeine’s neuroprotective properties, and its ability to suppress pro-inflammatory cytokine production. More studies are needed, however, to confirm these findings of caffeine involvement. (49)Hedström AK, Mowry EM, Gianfrancesco MA, Shao X, Schaefer CA, Shen L, et al. High consumption of coffee is associated with decreased multiple sclerosis risk; results from two independent studies. J Neurol Neurosurg Psychiatry Available here.

  • Caffeine and physical performance of the athletes
    Caffeine (specifically as a capsule/tablet or powder) when taken before exercise, is effective in increasing physical performance (especially in high-intensity workouts of prolonged duration).

    It improves performance by acting on several areas in the body: it increases focus and alertness, boosts energy, causes a higher release of epinephrine (adrenaline), increases the release of body fat for energy usage and aids in burning more fatty acids during exercise.

    For optimal absorption, it is advisable to take the supplement 60 minutes before the exercise. However, it is also effective when taken 15-30 minutes before exercise. Studies are inconsistent on the effectiveness of caffeine in strength-power exercises. (50)Schneiker KT, Bishop D, Dawson B, Hackett LP. Effects of caffeine on prolonged intermittent-sprint ability in team-sport athletes. Med Sci Sports Exerc. 2006 Mar;38(3):578-85. Available here. (51)Goldstein ER, Ziegenfuss T, Kalman D, Kreider R, Campbell B, Wilborn C, et al. International society of sports nutrition position stand: caffeine and performance. Journal of the International Society of Sports Nutrition 2010, 7:5.  Available here.

  • Caffeine and Diabetes 2
    Habitual caffeine consumption may reduce the risk of diabetes mellitus. (52)Jiang X, Zhang D, Jiang W. Coffee and caffeine intake and incidence of type 2 diabetes mellitus: a meta-analysis of prospective studies. European Journal of Nutrition. February 2014, Volume 53, Issue 1, pp 25-38. Available here. (53)van Dam RM, Willett WC, Manson JE, Hu FB. Coffee, Caffeine, and Risk of Type 2 Diabetes. Diabetes Care 2006 Feb; 29(2): 398-403. Available here. (54)van Dam RM, Hu FB. Coffee Consumption and Risk of Type 2 DiabetesA Systematic Review. JAMA. 2005;294(1):97-104. Available here. (55)Ding M, Bhupathiraju SN, Chen M, van Dam RM, Hu FB. Caffeinated and Decaffeinated Coffee Consumption and Risk of Type 2 Diabetes: A Systematic Review and a Dose-Response Meta-analysis. Diabetes Care, Volume 37, February 2014. Available here.
  • Caffeine and liver (cirrhosis)
    Caffeine in synergy with other compounds present in coffee may have protective properties against alcoholic and non-alcoholic cirrhosis, and reduce the mortality risk from cirrhosis. (56)Saab S, Mallam D, Cox GA, Tong MJ. Impact of coffee on liver diseases: a systematic review. Liver International. Volume 34, Issue 4, pages 495–504, April 2014. Available here. (57)Larsson SC, Wolk A. Coffee Consumption and Risk of Liver Cancer: A Meta-Analysis. Volume 132, Issue 5, May 2007, Pages 1740–1745. Available here. (58)La Vecchia C. Coffee, liver enzymes, cirrhosis and liver cancer. Hepatology. April 2005Volume 42, Issue 4, Pages 444–446. Available here.

Conclusion

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Caffeine is good for fast caffeine metabolizers (the majority of the population). Usually, they are moderate to high caffeine users and the amounts of 400-500mg of caffeine daily provides the maximum health benefits and the minimum negative side-effects.

Since not everyone can handle these amounts, the caffeine daily limit can be figured when the overdose symptoms are felt. If that is the case, reduce the amount of daily caffeine until the symptoms disappear.

Caffeine can be bad for you under the following scenarios:

  • If you are allergic to caffeine (hyposensitive to caffeine)
  • If you are a slow metabolizer (sensitive to caffeine)
  • If you overdose on caffeine
  • If you are overusing caffeine and are highly dependent on caffeine (caffeinism)
  • If you are pregnant
  • If it affects your sleep
  • If you are in the risk group of developing breast cancer
  • If you suffer from indigestion (GERD)

References   [ + ]

1. Fredholm BB, Battig K, Holmén J, Nehlig A, Zvartau EE. Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use. Pharmacological Reviews March 1, 1999 vol. 51 no. 1 83-133. Available here.
2. MedlinePlus. Caffeine in the diet. U.S. National Library of Medicine. National Institutes of Health. Available here.
3. Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992 May-Aug;17(2):139-70. Available here.
4. Wendl B, Pfeiffer A, Pehl C, Schmidt T, Kaess H. Effect of decaffeination of coffee or tea on gastro-oesophageal reflux. Aliment Pharmacol Ther. 1994 Jun;8(3):283-7. Available here.
5. Nwokediuko SC. Current Trends in the Management of Gastroesophageal Reflux Disease: A Review. ISRN Gastroenterology. Volume 2012 (2012), Article ID 391631, 11 pages. Available here.
6. Drugs. Caffeine. Available here.
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