Caffeine is used by over 80% of the US adult population and coffee is the most consumed liquid after water in an estimated volume of 1.6 billion cups a day. As a performance enhancer it has been shown to increase alertness, vigilance, attention, reaction time and attention to mention just a few. It has also been associated with a decreased risk of dementia! That’s a remarkable list and something that anyone seeking optimal health, longevity and performance would pay attention to. However, there is a darker side to caffeine and coffee consumption that like most socially accepted addictions we tend to avoid but probably all know exists.
My own experience with caffeine and coffee consumption demonstrates the dangers of habituation, dependence and withdrawal. I began drinking coffee like most adults in college. The demands of education mixed with the desires of late night social engagement results in this need for many. My use accelerated in medical school and by the time I was in practice I was drinking 8-10 cups of coffee per day. I felt no symptoms of excess use and initially believed I was not addicted because I could stop for a day or two and felt no symptoms of withdrawal. After going through functional and precision health fellowships I realized that like many of my patients I was a slow metabolizer of caffeine and that my lack of withdrawal was actually due to the fact that my blood levels of caffeine had not yet dipped low enough from their astronomical levels to result in withdrawal. I tested this theory with absolute abstinence and was astounded by the severity and duration of withdrawal that took place nearly 4 days after my last caffeinated beverage.
Most of the effects of caffeine are mediated through adenosine receptors in the brain and elsewhere on the body. Various adenosine receptor subtypes play different roles in the brain and periphery resulting in the numerous desired effects of caffeine on the body. These effects are seen at low doses around 100 – 200mg (1 cup of coffee). Higher levels of caffeine can induce intracellular calcium release which in turn increases endothelial nitric oxide production which may explain the performance enhancement seen with higher doses of caffeine use. This starts to occur after doses >400mg (2+ cups of coffee). At even higher doses caffeine can encourage the utilization of body fat for fuel over carbohydrates through activation of hormone sensitive lipase (HSL). This justifies the use of caffeine in weight loss nutraceuticals but the consumption levels required to reach these physiologic benefits are extremely high (1,000mg and up).
Studying caffeine benefits has numerous challenges though. Because over 80% of the population consumes caffeine regularly it is difficult to find healthy adults who are naïve to the drug. In addition the metabolism of caffeine is extremely varied with the half life of caffeine ranging from 2 to 12 hours. If you are unfamiliar with this concept that means that your body will metabolize half of the caffeine consumed somewhere between 2 and 12 hours after consumption. That’s extremely variable and makes safe recommendations for consumption difficult to make. This is driven by genetic polymorphisms, specifically Adora2a, as well as differences in absorption. The genetic variance is testable and something we do for all of our patients through Optimal Human Health Optimization programs.
If you consider the origins of caffeine it’s not surprising that it can have negative side effects too. It is a chemical produced by over 60 plants likely as a means of self defense. The plants derive no clear benefit other than using it as a pesticide. In fact it is toxic and sometimes lethal to many pests (including humans). Some of the negative effects of caffeine include increased blood pressure, anxiety, agitation, sleep disturbance, tremors, rapid heart beat (tachycardia) and at high doses death. Most of these are reported to occur with “intoxication” but that is only requires 500 – 600mg of caffeine. That’s as little as 3-4 cups of coffee which is easy to get in a single drink at Starbucks. When you consider that some people are drinking multiple of these beverages per day and may be slow metabolizers the blood levels of caffeine can easily stack with each dose resulting in very high levels. So, how is this tolerated? Through habituation.
The human body has the ability to develop tolerance to most exposures to some extent. The ability to tolerate caffeine has been demonstrated in both the brain and in the peripheral receptors. Tolerance results in an increased need of the same substance to get the desired result. Increased consumption also increases the risk of negative side effects. As use increases so does the risk of dependence on the substance to prevent withdrawal.
Ultimately, we need to look at caffeine as a potential benefit but recognize that it only works if we have not created dependence and habituation. To stay on the optimization side of that line caffeine must be used periodically with ample time to recover sensitivity of the adenosine receptors in between doses. Once your receptors are saturated and you have created dependence you are no longer likely seeing any benefit from the caffeine and are simply feeding an addiction. As I mentioned in a previous post, looking for addictions in your life is one of the keys to living optimally. Pulling back on caffeine consumption and using water treated organic decaffeinated coffee can reset the benefits of caffeine. For me, I drink 1 cup of decaf coffee and occasionally have green tea as well. This keeps me under 100mg daily and my morning routine and daily energy have never been better.