‘Pie hole’, colloquial for one’s mouth, is believed to have evolved in the USA in the 1980s from the British expression ‘cake hole’ (coined in the mid 20th century). Pie hole refers to a mouth, as in: Shut your pie hole or, in this case: Put less in your pie hole.

Wednesday, June 5, 2013

I Take Mine Tall, Dark and Rich... And Early

Coffee is one of the 5 most traded commodities worldwide. It's natural, it's a stimulant, it's brown, and you can drink it in your favourite mug whilst reading the paper (or, if you're under 50, your iPhone). The spotlight has been on coffee in recent months with new studies shouting praises for coffee in regards to health. Findings suggest coffee drinking (>3 cups/day) can decrease risk of heart disease, type II diabetes and even obesity. These are great findings, but they don't address the question many people ponder: "Will a cup of coffee with dinner keep me up tonight?" Join us as we escape the daily grind with a cup of Joe to explore the coffee grind.

Some evidence suggests that coffee consumption with lunch can reduce the risk of diabetes due to changes in glucose metabolism, compared to not drinking coffee at lunch. This association was found for both caffeinated and decaffeinated coffee. Sadly for the tea drinkers like me, no association was found between tea slurping and diabetes.

Very few studies have examined the effect of a 'normal' dose of caffeine in real life situations. Most studies evaluate very high caffeine doses (250-1200mg), mainly in men and in artificial lab settings.

A recent study examined the effect of a single cup of coffee on sleep in men and women with 'coffee sensitivity'. This was defined as subjects identifying an afternoon or evening coffee disturbing their sleep. Coffee sensitivity is thought to be caused simply by individual differences in coffee metabolism.

Participants were given a 3g bag of instant decaffeinated coffee (4.5mg caffeine) and a 3g bag of instant caffeinated coffee (90mg caffeine). Participants didn't know which bag contained which treatment. One bag was chosen and consumed after dinner and the other bag was brewed another night within 7 days. These conditions were kept as similar as possible:
  • Day of week
  • Activity during the day
  • Timing and content of dinner
  • Alcohol and cigarette consumption during the day
  • Bed time and rise time
The morning following coffee consumption, participants were asked to rate their quality of sleep between 0-100 (0 being excellent and 100 being poor), estimate how long it took them to fall asleep (sleep latency) and their frequency of waking during the night.

Results showed:
  • Quality of sleep was significantly worse with the caffeinated coffee
  • Significant sleep latency was reported with the caffeinated coffee
  • Frequency of waking was higher with the caffeinated coffee
Other findings:
  • The greater the time between drinking coffee and going to bed reduced the number of awakenings
  • At the conclusion of the study, 68% of participants correctly guessed which night they drank which coffee due to the effects
Very simple take home message this week: if you believe drinking coffee at night prevents you sleeping well, don't put it in your pie hole!


  1. Thanks for talking about coffee, Ms. Pie Hole!! Luckily, I'm one of those people without a coffee sensitivity. With or without a late night java, my sleep is relatively unaffected. Of course, I suffer from insomnia, so I'm limiting that analysis to the effects on nights when I'm not in the middle of an insomnia attack.

    But I do know several people who can't join me in an evening coffee. So sad!

    Also, thanks for linking to the science, I'm going to go read the source articles before bed :)

    I'm very interested in the benefits you cited. I wonder where the point of diminishing return is. >3 cups of coffee is correlated with decreases in risk that are pretty awesome, but how does this hold up at >5 cups or even >10! I know a LOT of people who pretty much mainline coffee for several hours a day, with some in the *dozens* of 6-8oz cups of coffee per day.

    I'd be interested in reading a follow-up to this article if you know anything about the other end of the spectrum, (a.k.a., NO MODERATION of intake).


    1. Hi Chris! I'm so glad you liked the article. Thank YOU for your comment and questions.

      It's interesting you ask about the no moderation aspect. I actually found an article that does show excessive coffee consumption (>5-6 cups/day) can have adverse effects. The study (in mice) found that excessive consumption of chlorogenic acid (found in coffee) inhibited fat loss and lead to insulin resistance (a characteristic of type II diabetes).

      So I guess, "everything in moderation" also extends to coffee.

    2. Wow, I didn't know that that CGA inhibited fat metabolism, but taking a deeper look at the chemistry it makes some sense. It's an antioxidant, but that on it's own doesn't mean it's a positive. It also slows glucose release to the blood stream, so I guess it kind of makes sense that it might have other effects on that particular pathway (insulin resistance). Crazy!

      I've had a partial blog post about coffee/caffeine and weight loss in my drafts for quite awhile, your article has definitely made me put some more thought into finishing it. When I do, I'll definitely need to link out to you for the nutrition end of the discussion!!

      Thanks again! I'm really enjoying your thoughtful (and researched) posts! Too few nutrition blogs (and others) actually link out to the hard science.

  2. Thalia, I enjoyed the article, of course with a great blend of coffee - Mclaughlin Max's Blend. ( Great dark coffee, beans are oily right out of the bag). Good research info to back up the claims. So much contradictory information on coffee that this sounds more credible with the science behind it. But sigh, I love my 5-6 cups on some days so will have to look at moderating. Keep up the good work.

    1. Thanks for your comment Randall. There is lots of research out about coffee lately. I guess the important thing is making sure whoever wrote it is credible and cites their sources (and that their sources are recent, peer reviewed journal articles, not wikipedia or something like coffeewillkillyou.com)