I have had a love/hate relationship with caffeine for the better part of the last seven years—a short time frame, no doubt, compared to the more devoted coffee drinkers among us. But in that time I’ve learned quite a bit about the compound known as 1,3,7 trimethylxanthine—and it's not all pretty.
In the grand continuum of drugs, caffeine is seen as mild, and with good reason. Compared to the effects of drugs such as cocaine and heroin, caffeine affects the brain in much less severe ways. Which is why it might come as a surprise that caffeine is not just an addictive drug, it’s also a model drug of dependence Caffeine as a model drug of dependence: recent developments in understanding caffeine withdrawal, the caffeine dependence syndrome, and caffeine negative reinforcement. Griffiths, RR and Chausmer, AL. Nihon Shinkei Seishin Yakurigaku Zasshi, 2000 Nov;20(5):223-31.
Few of us may think of the contents of our coffee mugs as being equal to a pill or a powder, but in essence that’s what us caffeine addicts are consuming every day. Whether you get your caffeine via coffee, energy drinks, tea, or soda, it retains the same effects. Let's take a closer look at exactly what caffeine does to our bodies and the consequences of caffeine dependence.
This Is Your Body On Caffeine
Caffeine is produced by more than 75 plants, which utilize it as a pesticide. Humans have demonstrated a very low, tolerable upper intake level—in other words, we aren’t adapted to high levels of caffeine consumption The effect of daily caffeine use on cerebral blood flow: How much caffeine can we tolerate? Addicott, MA, Yang, LL, Peiffer, AM, et al. Human Brain Mapping, 2009 Oct;30(10):3102-14. Since we’re talking about what is essentially a pesticide, this perhaps doesn’t come as a surprise.
Caffeine is a member of both the alkaloid family (along with morphine, nicotine, codeine, etc.) and the xanthine family, from which most stimulants are derived Caffeine and related purine alkaloids: biosynthesis, catabolism, function and genetic engineering. Ashihara, H., Sano, H., Crozier, A. Phytochemistry, 2008 Feb;69(4):841-56. Upon human ingestion, caffeine binds to adenosine receptors. Adenosine is an inhibitory neurotransmitter that slows activity in the central nervous system. When caffeine inhibits it, we feel less tired (which explains why caffeine is so appealing to those of us who are sleep deprived) and our neurons fire faster. Essentially our body thinks that some kind of emergency is happening, and it floods itself with dopamine, epinephrine, cortisol, and acetylcholine.
Caffeine also tightens muscles, dilates pupils, opens airways, increases pulse rate, and constricts blood vessels. This last effect is the reason why caffeine is sometimes included in pain relief medication, because less bloodflow to the affected area equals less perceived pain Caffeine as an analgesic adjuvant for acute pain in adults. Derry, CJ, Derry, S., and Moore, RA. Cochrane Database Systems Review, 2012 Mar 14;3:CD009281. Because of its biochemistry, caffeine is classified as an addictive substance Caffeine as a model drug of dependence: recent developments in understanding caffeine withdrawal, the caffeine dependence syndrome, and caffeine negative reinforcement. Griffiths, RR and Chausmer, AL. Nihon Shinkei Seishin Yakurigaku Zasshi, 2000 Nov;20(5):223-31.
Caffeine, Health Risks, and Addiction
Now officially classified as a disorder, caffeine dependence is real and ugly. Anyone who has missed their morning cup of coffee surely knows this. Whether you drink caffeine in large amounts or small, its consumption has been correlated to age-related diseases such as osteoporosis and premature aging syndromes, due largely to its ability to shorten telomeres (the ends of human chromosomes). Cellular aging also means early wrinkles; caffeine can also lead to gray hair and speed up hair loss (Perhaps paradoxically, one study suggests that caffeine consumption may help people live longer, while another found that caffeine boosts people's memories.).
Caffeine has particularly negative effects when it comes to getting high-quality zzzs. Many of us have heard that it’s not good to drink caffeine in the afternoon, because doing so may negatively affect sleep that evening. This results from the fact that caffeine’s half-life (or the amount of time it takes for half of the substance to be metabolized by the body) is roughly six hours. This means that at 10 p.m., some of that 2 p.m. coffee is still floating around in the bloodstream. And that means that caffeine may prevent us from getting a good night’s sleep, resulting in sleepiness the next day Effects of caffeine on sleep and cognition. Snel, J., and Lorist, MM. Progress in Brain Research, 2011;190:105-17. Caffeine consumption can also disrupt normal sleep patterns, meaning the sleep we do get isn’t as restful Effects on sleep stages and microarchitecture of caffeine and its combination with zolpidem or trazodone in healthy volunteers. Paterson, LM, Nutt, DJ, Ivarsson, M., et al. Journal of Psychopharmacology, 2009 Jul;23(5):487-94. The consequences of insufficient sleep include an increased likelihood to overeat, impaired cognitive performance, and endocrine disruption A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal-weight healthy men. Schmid, SM, Hallschmid, M., Jauch-Chara, K., et al. Journal of Sleep Research, 2008 Sep;17(3):331-4 Effects of sleep deprivation on cognition. Killgore, WD. Progress in Brain Research, 2010;185-105-29 Metabolic and endocrine effects of sleep deprivation. Copinschi, G. Essential Psychopharmacology, 2005;6(6):341-7.
Caffeine withdrawal, as anyone who has gone through it can tell you, is not a fun experience Caffeine withdrawal, acute effects, tolerance, and absence of net beneficial effects of chronic administration: cerebral blood flow velocity, quantitative EEG and subjective effects. Sigmon, S.C., Herning, R.I., Better, W., et al. Psychopharmacology, July 2009;204(4):573-585. While the withdrawal period is most known for causing headaches, it can also include unpleasant symptoms such as brain fog, lethargy, negative mood, sleepiness, depression, and, in extreme cases, vomiting A critical review of caffeine withdrawal: empirical validation fo symptoms and symptoms and signs, incidence, severity, and associated features. Juliano, LM and Griffiths, RR. Psychpharmacology, 2004 Oct;176(1):1-29. The good news is that long-term, there are no known ill health effects of caffeine withdrawal. However this is no solace to someone experiencing it!
So what’s the healthiest way to consume caffeine? If you can’t give it up entirely, one study suggests that consuming it in small amounts (roughly 100mg to 200mg, or approximately 1 to 2 cups of coffee) immediately prior to exercise might be beneficial for growth hormone production Caffeine Attenuates Acute Growth Hormone Response to a Single Bout of Resistance Exercise. Bo-Han, Wu and Jung-Chang, L. Journal of Sports and Science Medicine, Jun 2010;9(2): 262-269. Consuming caffeine via green tea is also a healthier option, as green tea contains healthful compounds like the antioxidant epigallocatechin gallate and the amino acid L-theanine Epigallocatechin Gallate (EGCG) Is the Most Effective Cancer Chemopreventive Polyphenol in Green Tea. Guang-Jian Du, Zhiyu Zhang, and Chong-Zhi Wang. Nutrients, Nov 2012;4(11):1679-1691. Even coffee boasts some impressive health benefits as long as it's consumed in moderation.
That said, if you're drinking more than two cups per day, it's probably a wise idea to gradually decrease your consumption. Cut back over a period of a few weeks in order to avoid the nasty withdrawal symptoms described above. If you stay within the lower end of the spectrum of caffeine intake, you will help yourself to minimize most of the deleterious effects of addiction Characterization of Individuals Seeking Treatment for Caffeine Dependence. Psychological Addict Behavior, Dec 2012;26(4):948-954.
Biochemically, caffeine is an addictive compound with several potential negative effects, though many of them can be mitigated by consuming caffeine only in moderation and from healthier sources such as coffee or tea. The trouble arises when large amounts of caffeine are used to cope with chronic sleep deprivation—and unfortunately, it seems both habits have become as American as apple pie. We are a country low on energy, low on sleep, and, as a result, high on caffeine.
Casey Thaler, B.A., NASM-CPT, FNS is an NASM® certified personal trainer and NASM® certified fitness nutrition specialist. He writes for Paleo Magazine®, The Paleo Diet®, and PaleoHacks. He also runs his own nutrition and fitness consulting company, Eat Clean, Train Clean® while pursuing his Ph.D in nutritional biochemistry. The views expressed herein are his. To learn more about Casey, check out his website or follow him on Twitter.