Some folks swear by their coffee, some don’t even like a sip. Below I outline some of the conclusions drawn from current research. The quick summary is – drink it in moderation if it works!
Is coffee dehydrating?
Let’s start with the reputation that coffee has a diuretic and dehydrating effect. While we once thought (and it is still commonly believed) that coffee causes dehydration, recent research shows otherwise. We have the military to thank for having done thorough research on the physiological effects of caffeine on hydration. Their incentive? Forces deployed in desert climates in the middle east.
Studying subjects who regularly consumed a relatively low amount of caffeine — equivalent to 1 six-ounce cup of brewed coffee (about 1oo mg caffeine) they found that over a 24 hour period, urine losses were similar to a person who had consumed no caffeine. Earlier studies had looked at urine collection just two to four hours after caffeine consumption (not the 24-hour picture), didn’t compare coffee to water, or used very high doses of caffeine (Journal of International Sports Nutrition, 2005. Armstrong). We now know people have similar urine volume whether they consume caffeinated or plain water. This may sound counterintuitive to you, since there can be a drying sensation in the mouth following coffee, but that’s actually caused by the astringency from the tannins present in coffee.
Of course, I’m not suggesting you use coffee to rehydrate. Good ol’ water and plenty of it is much better!
Caffeine and athletic performance
Studies show that caffeine in moderate amounts (250-300 mg per day) does enhance physical performance and makes the effort feel easier for endurance activities and short, high-intensity activities. Improvement in endurance is likely due to the positive effect of caffeine on nerve impulse transmission.
Be warned however, that people have varied responses to caffeine. Some people are very sensitive and need to limit consumption to avoid negative side-effects such as jitteriness, insomnia, nausea, increased blood pressure and loose bowels. Other people can enjoy their Cup of Joe without any ill effect. Just remember to listen to your own body to determine the ideal for your unique body/brain. Also, remember that brewed coffee has no calories but a Carmel Frappuccino has 410 sugary calories!
Coffee and stress
Neuroscientists have newly clarified the definition of stress to mean: “conditions where an environmental demand exceeds the natural regulatory capacity of an organism.” (Koolhaas, et al. Stress revisited. Neurosc Biobehav Rev. 2011 Feb)
What this means is that whether coffee is a negative stressor to you depends upon your unique body, how much stress you already experience and how strong your adrenal glands are (adrenals=adrenaline=fight or flight). Coffee is a stimulant and a drug albeit a widely used and pleasant one for many, but for some, it leads to anxiety, adrenal exhaustion and other unwanted nastiness.
So, in conclusion, enjoy your coffee in moderation if it’s working for you. However if coffee crowds out good nutrition, puts you on the energy roller-coaster or if you are caffeine sensitive (a genetic trait that causes the stimulant to metabolize more slowly) then switch to green tea or gradually taper off.
To your great health!
Cassandra Mick, CNE