No, Coffee Will Not Dehydrate You
When it comes to healthy eating and nutrition, it's important (and sometimes difficult) to get past the myths and misconceptions that are drilled into our heads every day. (For instance, eating in moderation as an effective diet technique.) Or, the assumption that new research has shown to be false: that coffee dehydrates you.
A January 2014 study published in the journal PLOS ONE has found that, contrary to what many people think is true, your morning cup (or cups) of Joe will not dehydrate you. In fact, moderate coffee consumption will keep you just as hydrated as if you were to drink water instead, the study concludes.
So what counts as moderate consumption? According to the study, four cups. Researchers looked at a group of 50 male coffee drinkers taking in four mugs (200 milliliters each) of black coffee compared to those drinking the same amount of water, every day, for three days. After a 10-day break period, the groups switched roles. Researchers used a variety of tests to measure hydration, including weight and blood and urine analyses.
The results showed no significant differences in total amount of body water or in any of the blood tests. There was also no significant difference in urine volume or concentration between the two groups.
But although a few cups shouldn't throw off your levels, that doesn't mean you should stop drinking water and replace it with java, notes nutritionist Leah Kaufman, who doesn't recommend relying on coffee to meet your body's hydration needs. "Although this study has shown positive effects, the limitation on number of participants and length of time of study makes me hesitant to tell my patients that drinking just coffee is fine for hydration," she says. "For now, water should be your go-to liquid for hydration, but a small amount of coffee per day does not seem to pose any threat to one's health."
Indeed, the men in this study were drinking water in addition to coffee during the trial period, so it's not like they were relying entirely on java for hydration. What's more, the participants are habitual caffeinators, drinking at least three cups a day, which means their bodies are probably habituated to the diuretic effects.
Kaufman also suggests that anyone regularly participating in physical activity should be wary of these findings. "An athlete, or even someone who is just participating in 45 minutes of fitness on most days, needs to stay well hydrated and their go-to fluid should always be water," Kaufman suggests. "It would be interesting to see a study done with a greater amount of participants who were participating in exercise." But until this is done, we can't really tell what the hydration effects would be.
"Water can help energize muscles, keep a healthy glow and help maintain normal bowel function," Kaufman says. So make sure you keep it in your rotation throughout the day between trips to the Keurig machine. Your health and beauty will be better off when you reap the benefits of both of these beverages at once.
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