848. An episode we did earlier this month about coffee prompted questions from many listeners. Does coffee spike your cortisol? How does it affect the bladder? Is espresso healthier than drip? Answers to your questions here.
848. An episode we did earlier this month about coffee prompted questions from many listeners. Does coffee spike your cortisol? How does it affect the bladder? Is espresso healthier than drip? Answers to your questions here.
Related episodes:
846 - Fact check: Is it bad to drink coffee on an empty stomach?
Find a transcript here.
Clearly Nutrition Diva listeners enjoy their java because I got an unusual number of emails from listeners in response to my recent episode about drinking coffee–-including many great questions about coffee, cortisol, caffeine, and more. Grab a cup and sidle up for the answers.
Hello and welcome to the Nutrition Diva podcast, a show where we take a closer look at nutrition headlines, research and trends and answer your food and nutrition questions. I’m your host, Monica Reinagel and I heard from a lot of you in response to my recent episode on whether or not it’s OK to drink coffee on an empty stomach, with some really good questions–and I wanted to share the answers with all of you.
Abbey wrote in to say: “My colleagues have been afraid to drink coffee before breakfast because they read caffeine raises cortisol which will impact blood sugar and without food there’s nothing to stabilize blood sugar. What would you say to that?”
I would say that your colleagues are mashing together a few real phenomena in a way that doesn’t really make sense. Let’s see if we can help them (and you) sort it out.
First, it is true that caffeine can cause an increase in cortisol secretion, but the effect is pretty modest and even more so if you are a regular coffee drinker. However, even if you are not a regular coffee drinker, morning is the time of day that your cortisol levels are already likely to be their highest. This is just part of the normal circadian rhythm.
Cortisol plays a specific role in maintaining your blood sugar during long periods without food…as is usually the case overnight. This is probably why cortisol levels tend to be at their peak in the morning, and it’s also why any small bump that you might get from a cup of coffee is not going to have much impact.
The relationship between caffeine and blood sugar is a bit more complex. Caffeine does tend to temporarily blunt insulin sensitivity. If you were to follow a dose of caffeine with a dose of sugar, your blood sugar might peak a bit higher than if you had the sugar without the caffeine beforehand.
This is the type of thing that can be measured in a lab, but I’m not sure how much relevance it has to everyday life (especially if you do not have diabetes). It’s perfectly normal for your blood sugar to go up after meals. As long as it gradually returns to normal, this is not a concern.
In fact, regular coffee drinkers actually have a reduced risk of developing Type 2 diabetes. This effect is seen with both regular and decaf coffee and not observed in tea drinkers. This suggests that the protective effects may not be directly related to the caffeine but to other compounds in the coffee. But it may be reassuring to your co-workers.
And finally, the argument that “without food, there’s nothing to stabilize blood sugar” is the most muddled of all. If you haven’t eaten, your blood sugar is already being “stabilized” or maintained by your various organs and hormones, not by food. And adding food doesn’t really affect your cortisol levels one way or another. But as the food is digested and absorbed, it will generally raise your blood sugar and insulin levels (not “stabilize” them).
The bottom line is that drinking a cup of coffee before breakfast is unlikely to have any meaningful impact on cortisol or blood sugar regulation over the course of the day.
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Here’s a question from Lyn on whether coffee irritates the bladder. “I’ve been told caffeine is a bladder “irritant”. Are there other foods or drinks that should be avoided by people with an overactive bladder?”
People with overactive bladder frequently report that drinking coffee or other caffeinated beverages worsens their symptoms. Many people assume this is because caffeine is a diuretic. However, caffeine’s diuretic effects disappear almost entirely when it is consumed regularly. It probably has more to do with its effects on smooth muscles and nerves, which contribute to that sensation of “urgency.”
In any case, limiting caffeine to less than 100mg a day (that’s one small coffee a day or a couple of cups of black tea) is good advice for those with this condition. There is also good evidence to support limiting or avoiding alcohol and carbonated beverages. Advice to avoid artificial sweeteners, acidic or spicy foods is not as well-grounded in evidence. If you find it helps, great. But if it doesn’t seem to have any impact, there may be no benefit to avoiding those foods.
(In general, food restrictions can make life more effortful, isolating, and inconvenient. So, I’m always on the lookout for opportunities to lift unnecessary embargoes.)
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And here’s one last question from Ben: “I used to drink percolator coffee but after living in Italy, I upgraded. Now, I drink espresso made either in a stove-top coffee maker or from an espresso machine. How does espresso compare to brewed coffee?”
Different brewing methods (percolator, french press, drip, and even whether you make espresso in a moka pot or espresso maker) all impact the final product.
Now obviously, taste and texture is subjective--what tastes bold to one may taste burned to another. And my full bodied cup may be your cup of sludge. But there are some objective differences as well. Let's start with caffeine.
Espresso is more concentrated: about 60 to 80 milligrams of caffeine per one-ounce shot. That’s roughly two to three times the caffeine concentration of brewed coffee. But we also tend to drink it in much smaller quantities. Then again, if you’re pulling multiple shots, the caffeine adds up quickly.
Next, antioxidants.
The high temperature and pressure used to make espresso extract more antioxidants per ounce than most other brewing methods. Again, though, we’re back to volume: You may get more antioxidants per ounce, but fewer ounces overall.
Among the non-espresso methods, French press tends to extract the most antioxidants because the grounds are immersed in hot water for a longer time. Drip and pour-over are a bit lower in antioxidant content. Percolators may be the worst of the bunch, because repeatedly cycling hot water through the grounds can actually degrade some of those antioxidant compounds.
And as you may remember from the previous episode, chlorogenic acids and antioxidants tend to travel together, for better or worse. So, French press may be higher in antioxidants but it will also likely be higher in chlorogenic acid–which may be a concern if your stomach is sensitive, because both chlorogenic acid and caffeine stimulate gastric acid secretion.
If you’re looking for the most stomach-friendly brew, that would probably be a darker roast (roasting reduces chlorogenic acid) made in a drip coffee maker or pour-over setup. Adding milk can also help, not because it makes the coffee less acidic, but because the proteins in the milk bind to the chlorogenic acids.
Finally, there’s the cholesterol question. Paper filters trap compounds called diterpenes that can modestly raise LDL cholesterol. For most people, this isn’t a problem. But if you drink a lot of coffee every day and you’re concerned about cholesterol, you might want to favor paper-filtered drip coffee. French press and percolators let more of those compounds through. Espresso and moka pot coffee fall somewhere in between.
Thanks to all of you who write in week after week with your great questions and comments. I always enjoy hearing from you and answering your questions on the show. If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com. And if you'd like to find out about having me speak at your next live or virtual event, you'll find more information at wellnessworkshere.com.
Nutrition Diva is a Quick and Dirty Tips podcast. Holly Hutchings is our Director of Podcasts. Steve Riekeberg is our audio engineer, Morgan Christianson heads up Podcast Operations & Advertising, Rebekah Sebastian is our Manager of Marketing and Publicity, and Nat Hoopes is our Marketing and Operations Assistant. I also wanted to say a special welcome to Maram Elnagheeb, our new Podcast Associate. Thanks to all of them and thanks to you for listening!