Medicine

Don’t reach for that cold one, just yet!

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There was a time when I would grab a 2 L bottle of diet coke after my swim. Of course, back then (not so long ago, about 15 years ago), that was but one of about 4 such bottles i downed a day. Plus, five- maybe six- cups (no wimpy sizes, here- 500 mL, for sure) of coffee in the morning and evening. But, now it’s just coffee and water that I imbibe.

But, it turns out, research shows that hot drinks may be the better way to cool off. Yes, HOT, not cold. The trick our body uses is evaporative cooling. When we sweat, that fluid exuded evaporates to the air, cooling our skin and dropping our temperatures. And, now, Dr. Ollie Jay (with two graduate students, AR Bain and NC Lesperence) of the University of Ottawa has shown that our temperature sensors (in the mouth, throat, and stomach) will exude more sweat if we imbibe hot, rather than cold, beverages. The results will be published in Acta Physiologica.

Body Thermoregulation

At the Thermal Ergonomics Lab of the University of Ottawa, 9 male volunteers were asked to bicycle at a moderate rate for 75 minutes. (Moderate exercise was determined by maintaining the body at 50% of maximum oxygen demand [VO2, max]) While they cycled, they were afforded drinks at 1.5, 10, 37 and 50 C, at intervals of -5, 15, 30, and 45 minutes. Instead of just monitoring body temperature via rectal thermography, the group examined the metabolic rate and employed eight thermometers about the body, an esophageal probe, and a rectal thermometer. This afforded them the ability to effect partitional calorimetry, which means they could determine (maybe estimate is a better choice) the total amount of heat entering and leaving the body.

If they had just used rectal thermography, cold water (or ice water) lodged in the stomach would radically affect the measurements- even if the rest of the body was unchanged in its temperature. Which is why all the other measurements were required to put this theory to the test.

And, the results? Drinking hot water elicted a sweat response that cooled the body far in excess of the temperature rise resulting from the heat of the drink. Cooler drinks elicited the opposite response, which meant the cooler drink effected less cooling.

But… this all assumes that we can effect evaporative cooling. If the humidity is high- evaporative cooling is virtually non-existent. If we are wearing too many clothes- same result. Or, if we are exercising vigorously- also the same result. if we can produce more sweat than can safely evaporate, our core temperature will rise, and not be lowered. (Dr. Jay proclaims that if sweat is dripping off our bodies, then choose the cold drink and not the hotter one.)

Another approach is to drink those ice drinks- you know, slushies or ice rages. Because these icy drinks will undergo a phase change (from solid to liquid) in our bodies that will draw significant heat from the body. This may be better to do before we exercise, so that we can lower our core temperature before the event.

Which brings up another query. What happens if we drink mentholated drinks or capsaicin (hot peppers)? The former activates our mouth’s cooling sensors, the latter our heating sensors. Or, if we bypass the mouth and feed water directly to our stomach via nasogastric intubation? I guess we’ll have to wait for Dr. Jay’s next publication.

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25 thoughts on “Don’t reach for that cold one, just yet!”

  1. Not being a scientist (or PhD), sometimes I lose a bit in the vernacular. Still, I learned a lot working for a client who published ‘The Chinese Almanac.’ Food choices do affect how our body responds to temperature and other issues. One surprising idea he shared with me is green tea is cooling and ginger tea is warming. The whole ancient Chinese medicine philosophies make a lot of sense when you think about it (food choices that draw on those naturally available during particular seasons) and even more so when you start to notice what happens when you apply them. I’m not sure if the ingredients in the hot vs. cold drinks were factored in during this study, but this would be worth noting.
    Nanette Levin recently posted..Marketing strategies are useless without people

    1. The ingredients were non-existent. To keep things equal, Nanette, it was hot water or cold water.
      I will have to check that out with green tea and ginger tea- both of which are not among my even abnormal drinks.

      Thanks for the information AND the comment.
      Roy

  3. Hi again Sir Roy. I live in a tropical country and I’m used to having a hot and humid environment. My grandma once told me that to keep my body cool, I have to drink hot beverages such as coffee, tea or “salabat” (ginger tea). Well, it works since I can really feel the cooling effects as I sweat. Also, I eat spicy foods. But then again, its all about control since when I drink too much coffee, I can’t sleep. :). Anyway, thanks for the insight Sir Roy. 🙂
    deanne sotero recently posted..בני ברוך

    1. Ah, the issue of coffee. I have always been lucky that coffee does not have the affect upon me (it also means it won’t wake me up, should I need that pickup, though).
      Glad to see you’ve known about these facts for a while, Deanne!

      Roy

  4. Interesting. You always provide posts worth thinking about. I usually use ice chips rather than drink water. I find that drinking water often bothers my stomach. I can down ice chips all day though. I think the other thing to consider is to drink water like smart water that has electrolytes. If you’ve been sweating, that’s essential.
    Julia Neiman recently posted..Top 3 Tips to Cultivate Gratitude

  5. Hi Roy!
    another informative blog by you .i like your blog.you really care about us and aware to us.this is interesting.i usually use hot drink rather than cold drink.
    thanks to advice.

    1. Actually, Gordon, you should drink a cold drink BEFORE you exercise. It will hydrate you (letting you “sweat” without losing too much water) AND lower your core temperature before you exercise.

      Thanks for the visit and the comment.

  7. I wonder if it works the other way around? I love eating ice-cream in winter, I feel as though my body works to warm up from the cold ice-cream. Maybe that is just my long term habitual excuse for eating ice-cream. When I lived in Singapore it was common to have a warm drink or luke warm, drinks were rarely served cold unless specified as the Singaporeans in general claim that cold drinks are not good for us.
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        1. It depends if you consider it just a league or a collection of teams? I consider it the latter…
          re: The ever-changing helmets… Not fast enough. Moreover, the data demonstrates that they do little other than encourage folks to hit harder, thinking they are protected…
          We need docs to determine who can go back in after a hit- not a coach, whose only determinant is winning (or money).

          (Of course, I believe this sport is now akin to that of boxing- not really as “important” as one thought it was, at first, Gordon…

  10. I need to try this. The current temperature here is over 110 F and I always use lemonade or iced tea to “cool off”. Summers are when I have absolutely no coffee, and just green tea once in the morning. I might try using hot tea to cool off!

    I am making myself the guinea pig in this little experiment… though I have subjective influences of judgment to totally mess the results!

    1. Hajra, I love scientific experiments!
      Don’t forget what I also said… it’s best to cool your core temperature BEFORE your exercise. That is even more effective than cooling it after you start. (Of course, if it’s 110 in the shade I doubt you are doing exercise outside, anyway.)

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