Caffeine: Nutritional Jolt? by Dr. Chrisopher Jackson, PhD, DOM
A prominent drug found in the diets and cultural practices of populations throughout the world, caffeine is consumed by young and old alike, and marketing campaigns are now targeting younger populations directly (Turley et al., 2012). Along with any controversy over marketing efforts of caffeine-containing drinks toward children, there exists some controversy over the effects or perceived effects of caffeine among researchers. According to a study by Rogers et al. (2005), perceived stimulant effects of caffeine may be essentially the result of reversal of withdrawal from caffeine, rather than a beneficial performance improvement. A study by James, Gregg,, Kane, and Harte (2005), which monitored salivary caffeine levels to test compliance, appeared to agree with Rogers et al. (2005). One of this study's authors (James) had flagged, in a 1994 study, the inappropriate accounting for the consistent use of caffeine by most study participants in prior placebo-controlled studies of the potential performance and mood-altering effects of caffeine (James et al., 2005).
The study by Rogers et al. (2005) examined differential effects on fully withdrawn caffeine users (after 3 weeks of abstinence, also confirmed using salivary caffeine levels versus overnight withdrawn users). Rogers et al. (2005) found that overnight withdrawal impaired cognition, which returned to prior levels upon subsequent caffeine consumption. The same sort of improvement was not evident in fully withdrawn participants. However, caffeine increased jitteriness, reduced complaints of light-headedness, and improved clear-headed thinking in both fully and overnight withdrawn populations (Rogers et al., 2005). Aside from any performance improvements, additional problems with long-term caffeine consumption include osteoporosis, apathy, hyperstimulation of adrenal glands, and cardiac arrhythmia (Gummadi, Bhavya, & Ashok, 2012). In fact, greater all-cause mortality was seen in a study of 43,727 participants, particularly with men who consumed more than 4 cups of coffee per day (Liu et al., 2013).
Generally, cognitive performance and emotion studies have shown some of the effects of caffeine. James et al. (2005) included study of the differences in caffeine response between men and women. Memory tests showed better performance by women when both groups were rested, but performance that was poorer than men when the groups were sleep deprived (James et al., 2005). Caffeine's action on adenosine receptors to reduce inhibition of acetylcholine release (resulting in the presence of additional acetylcholine) may explain the memory improvements (Yang, Palmer, & de Wit, 2010). The negative effects of caffeine withdrawal included headaches, sleepiness, a perceived increased difficulty with cognitive challenges, and a reduction in the state of alertness (James et al., 2005; Rogers et al., 2005). Moods were improved slightly in both fully and overnight withdrawn populations.
Further studies regarding physical performance reveal some interesting results as well. Enhanced capacity for intense physical performance (ergogenicity) has been demonstrated following administration of caffeine (Duncan, Taylor, & Lyons, 2012). Essentially, this particular study showed a reduction of symptoms of fatigue after exercise that was of high intensity. Comparing the effects based on gender, Turley et al. (2012) reported that the blood pressure of boys and men was higher under the administration of 5mg/kg of caffeine. In adults, mean and peak power were significantly higher under administration of either 2.5 or 5.0 mg/kg of caffeine (Turley et al., 2012). According to Astorino, Terzi, Roberson, and Burnett (2011), muscle performance may improve with caffeine intake, whereas no amelioration of leg pain levels was seen. There is some controversy over the effects and levels of the internal stressors of the body (adrenal hormones). The study by Yang et al. (2010) suggests some direct negatives of elevated caffeine consumption, such as increased risk of myocardial infarction (heart attack), possibly due to elevation of catecholamine production. Yet, a study by Paton, Lowe, and Irvine (2010) of cyclists engaged in high intensity intermittent sprinting indicated enhancement of muscle performance, strength, and development with 240 mg caffeine administration. The study suggests that caffeine raises testosterone and lowers cortisol, while slowing the rate of development of fatigue (Paton et al., 2010). Note that all of the study participants received the same quantity of caffeine rather than a weight-proportioned dosage, possibly affecting the accuracy of corresponding physiological variations. Also, none of these studies addressed the possibility of a reverse withdrawal effect. An interesting point made by James et al. (2005) was that smoking speeds the elimination of caffeine, whereas contraceptives lengthen the time to elimination. According to James et al. (2005), without the influence of contraceptives or nicotine, symptoms of withdrawal typically appear 12 to 16 hours after consumption and peak after 24 to 48 hours. Therefore, the timing of measurement could influence the results in studies of physical performance related to caffeine ingestion.
According to Koppelstaetter et al. (2010), excitation of brain neurons involved in attention and executive thought processes may be at the root of the action of caffeine. The affect of caffeine on neurotransmitters noradrenaline, dopamine, and acetylcholine may lead to this excitation and resultant cognitive processes (Koppelstaetter et al., 2010). Yet, according to Yang et al. (2010), variations in reactions to caffeine may be influenced by genetic variations, such as polymorphisms in adenosine receptors, and ethnicity, as found in Caucasian metabolization of caffeine, which takes place at a faster rate than in Asians and Africans. Additionally, specific genetic predispositions may influence likelihood of dependency, withdrawal symptoms, insomnia or sleep disturbances, and anxiety, independent of any other addicitve predispositions. However, the choice of food source for the caffeine is somewhat culturally dependent, and may be influenced by the amount of caffeine in each of the food sources - tea, coffee, energy drinks, sodas, and chocolate (Yang et al., 2010).
Other combinations with caffeine are important as well. According to Sünram-Lea, Owen-Lynch, Robinson, Jones, and Hu (2012), the combination of glucose and caffeine may be of some benefit under stresssful conditions. Reduction in cortisol production and improvement in cognition were demonstrated when glucose was administered following a stressor (as opposed to prior to stressor exposure which has been shown to increase cortisol production). Caffeine mildly increased cortisol after stress. However, the presence of amino acid L-theanine in tea may offset the caffeine, since tea decreased cortisol response after stress (Sünram-Lea et al., 2012). It should be noted that the cyclical nature of cortisol (a factor in the circadian rhythm) could have affected the levels obtained, as well as response sensitivity. Also, the possibility of reversal of withdrawal symptoms was not addressed in this study.
Given the effects of caffeine, particularly the negative effects, other options could be examined. Decaffeination would be a viable and possibly preferable option for many who would like to consume the foods that typically contain caffeine. The preference would be for a process that accomplishes this function naturally and without toxic by-products (Gummadi et al., 2012). According to Gummadi et al. (2012), the typical chemical processes for decaffeination are not specific to caffeine, and create environmentally problematic by-products. One particular alternative to this form of decaffeination is microbial degradation, which is specific to caffeine, produces useful by-products theophylline and theobromine, and does not create the harmful by-products (Gummadi et al., 2012).
Another option would be to use a caffeine substitute. As with caffeine (due to withdrawal or otherwise), the herb Rhodiola rosea has been shown to improve athletic performance (enhancing ergogenicity), reduce fatigue, and improve cognition (Lee, Kuo, Liou, & Chien, 2009). All of this makes Rhodiola rosea a viable substitute for caffeine, especially since it is available as a tea. However, similar to caffeine again, Rhodiola rosea side-effects may be experienced, such as minor headaches, insomnia, and hypersalivation (Lee et al., 2009).
In summary, caffeine is simply a drug, and as with all drugs there are side-effects and withdrawal symptoms involved in the use or abuse of the drug. These effects include mood alterations, jitteriness, cardiovascular effects, possibility of myocardial infarction (heart attack), as well as muscular, and hormonal changes, particularly of a steroidal nature. Similar in many ways to anabolic steroids, and producing similar effects, the dangers of caffeine abuse are severe. Also, as is common with other drugs, addictive properties are evident. The addictive cycle is present due to the effects of withdrawal and its tendency to evoke a subsequent return to some form of the drug (chocolate, coffee, tea, cola, or energy drink). It is therefore advisable to examine further alternatives or to apply more stringent controls or medical oversight to the use of the drug caffeine. When is the last time your doctor asked you if you or your child drank caffeinated drinks? The studies examined herein would suggest that it would be wise to make this a standard question for every patient.
Copyright 2014 by Dr. Christopher Jackson, PhD, DOM
Astorino, T. A., Terzi, M. N., Roberson, D. W., & Burnett, T. R. (2011). Effect of caffeine intake on pain perception during high-intensity exercise. International Journal of Sport Nutrition & Exercise Metabolism, 21(1), 27-32.
Duncan, M. J., Taylor, S., & Lyons, M. (2012). The effect of caffeine ingestion on field hockey skill performance following physical fatigue. Research in Sports Medicine, 20(1), 25-36.
Gummadi, S., Bhavya, B., & Ashok, N. (2012). Physiology, biochemistry and possible applications of microbial caffeine degradation. Applied Microbiology and Biotechnology, 93(2), 545-554. doi:10.1007/s00253-011-3737-x
Ishaque, S., Shamseer, L., Bukutu, C., & Vohra, S. (2012). Rhodiola rosea for physical and mental fatigue: a systematic review. BMC Complementary And Alternative Medicine, 1270. doi:10.1186/1472-6882-12-70
James, J., Gregg, M., Kane, M., & Harte, F. (2005). Dietary caffeine, performance and mood: enhancing and restorative effects after controlling for withdrawal reversal. Neuropsychobiology, 52(1), 1-10.
Juliano, L. M., Evatt, D. P., Richards, B. D., & Griffiths, R. R. (2012). Characterization of individuals seeking treatment for caffeine dependence. Psychology Of Addictive Behaviors, 26(4), 948-954. doi:10.1037/a0027246
Koppelstaetter, F., Poeppel, T., Siedentopf, C., Ischebeck, A., Kolbitsch, C., Mottaghy, F., & ... Krause, B. (2010). Caffeine and cognition in functional magnetic resonance imaging. Journal of Alzheimer's Disease: JAD, 20 Suppl 1S71-S84. doi:10.3233/JAD-2010-1417
Lee, F., Kuo, T., Liou, S., & Chien, C. (2009). Chronic Rhodiola rosea extract supplementation enforces exhaustive swimming tolerance. The American Journal Of Chinese Medicine, 37(3), 557-572.
Lien, L., Lien, N., Heyerdahl, S., Thoresen, M., & Bjertness, E. (2006). Consumption of soft drinks and hyperactivity, mental distress, and conduct problems among adolescents in Oslo, Norway. American Journal of Public Health, 96(10), 1815-1820.
Liu, J., Sui, X., Lavie, C., Hebert, J., Earnest, C., Zhang, J., & Blair, S. (2013). Association of coffee consumption with all-cause and cardiovascular disease mortality. Mayo Clinic Proceedings. Mayo Clinic, 88(10), 1066-1074. doi:10.1016/j.mayocp.2013.06.020
Paton, C., Lowe, T., & Irvine, A. (2010). Caffeinated chewing gum increases repeated sprint performance and augments increases in testosterone in competitive cyclists. European Journal of Applied Physiology, 110(6), 1243-1250. doi:10.1007/s00421-010-1620-6
Pettit, M. L., & DeBarr, K. A. (2011). Perceived stress, energy drink consumption, and academic performance among college students. Journal of American College Health, 59(5), 335-341.
Rogers, P., Heatherley, S., Hayward, R., Seers, H., Hill, J., & Kane, M. (2005). Effects of caffeine and caffeine withdrawal on mood and cognitive performance degraded by sleep restriction. Psychopharmacology, 179(4), 742-752.
Sünram-Lea, S., Owen-Lynch, J., Robinson, S., Jones, E., & Hu, H. (2012). The effect of energy drinks on cortisol levels, cognition and mood during a fire-fighting exercise. Psychopharmacology, 219(1), 83-97. doi:10.1007/s00213-011-2379-0
Turley, K. R., Rivas, J. D., Townsend, J. R., Morton, A. B., Kosarek, J. W., & Cullum, M. G. (2012). Effects of Caffeine on Anaerobic Exercise in Boys. Pediatric Exercise Science, 24(2), 210-219.
Yang, A., Palmer, A., & de Wit, H. (2010). Genetics of caffeine consumption and responses to caffeine. Psychopharmacology, 211(3), 245-257. doi:10.1007/s00213-010-1900-1