Ask the Diet Doctor: Find Your Optimal Coffee Intake

Q: Help! I am under way too many deadlines at work and need to get focused, stat. Is coffee really the answer for me?

A: It could depend on who you are. Interestingly, Brian Little, Ph.D., author of Me, Myself, and Us: The Science of Personality and the Art of Well-Being, has recently made headlines discussing how your personality type could impact your body's response to caffeine. How so? Extroverts, he says, benefit from the effects of caffeine while introverts could actually experience detrimental effects.

While that may sound crazy, the idea isn't new. In fact, the caffeine/personality connection dates back to the mid-1970s, but the results of this research has been brought into question by other researchers. A 1999 study found no difference in response to caffeine effects between introverts and extroverts. But in 2013, the largest study (128 people) looking at the different responses between introverts and extroverts and caffeine found that a low dose (similar to a shot of espresso) enhanced memory tasks for extroverts, while everyone benefited from an improvement in reaction time.

In sum, the body's response to caffeine is very individual. Furthermore, how your body responds to a triple espresso before a big meeting can vary-depending on your caffeine tolerance (heavy, frequent, or not a coffee drinker at all), general stress levels, sleep habits over the subsequent week, and more. It is important to know your body and how it responds to one of the most widely used "drugs" available.

If coffee gives you the jitters-but you want to see if you can reap the cognitive benefits of caffeine-try supplementing with something called l-theanine, a unique amino acid found primarily in tea that essentially works by taking the edge off of caffeine without decreasing its effectiveness. (The effect is enhanced with a larger dose, only achieved via supplementation.) The potential negative effect of caffeine with introverts has to do with increasing their level of arousal to a place that is detrimental. L-theanine could potentially blunt those effects as it stimulates alpha waves in your brain, making you mroe relaxed. Research with caffeine and L-theanine also shows that this combo can lead to sustained focus and an increased ability to multitask.