Is coffee dangerous? I have said for years that one day, the studies will point towards Starbucks being a leading cause of mortality in the U.S. This week the first large study of that type appeared. It showed that men and women who drink 4 or more small cups of coffee a day have between a 50-100% greater risk of dying over 31 years. The coffee industry, after funding many miracle drug studies for their product, reacted with a bevy of paid university talking heads to refute the study. However, IMHO caffeine is an epigenetic public health disaster that’s fueling the expanding American waistline. Let me explain.
First, how much coffee are we talking about? A Starbucks venti has 20 fluid ounces for a hot drink and 24 for a cold one. This study called a cup of coffee 8 ounces, so if you have a venti iced coffee, you’re 3/4 of the way there. If you like shots of espresso instead, two shots have about the same amount of caffeine as an 8 ounce cup of coffee, so that quad shot latte gets you half way there.
Second, what’s epigenetic? This is when people with certain genes in a population respond a certain way to something, while others with different genes do not. As a result, epigenetics is how genes interact with the environment and as a result, these phenomena can be very tough to study. In this case, I believe some of us have a gene set that was selected at the time of ice ages that allows our bodies to run a slightly higher blood sugar. This is explained nicely in the book, Survival of the Sickest. In an ice age this can be a huge survival advantage, as it acts like anti-freeze for the blood. On the other hand, the same phenomenon that helps protect blood from freezing (a high blood sugar) also produces a tendency for early onset diabetes. The good news is that this problem won’t appear unless the conditions are right. So if you’re living on the edge of starvation all the time and burning massive calories just staying alive, like our distant ancestors, these diabetes genes are relatively quiet. On the other hand if you’re driving everywhere, don’t exercise, and eat way too many supersized calories (like most Americans), they become very active. This is where Starbucks comes in, which in this latter situation is like throwing gasoline on a fire.
We’ve known for a very long time that caffeine can have a profound effect on diabetics. Any good diabetes educator will tell adult onset diabetics that caffeine raises blood sugar and therefore drinking coffee will raise their blood sugar. Large studies looking at many different controlled trials have confirmed this effect. However, this effect isn’t the same for everybody. For example, caffeine given to normal rats does nothing to their blood sugar (but they can sure run the heck out of that little wheel), whereas it whacks out the blood sugar of diabetic rats. And there’s the rub. Many of the caffeine as miracle drug studies you’ve seen are small (and funded by the coffee industry). If they happen to have a large fraction of people in them without these ice age genes, coffee may be a big net benefit. In addition, the effects of the fact that caffeine raises blood sugar may not be seen for decades, just like you’d be hard pressed to tell over a few years that smoking cigarettes did anything negative.
So how does this effect you? After all, while you may have some older diabetics in your immediate family, you’re not a diabetic. As I like to tell patients, if you have the genes and live like the average American, you’re always a diabetic in training. To explain that, I need to tell you a tale of my wife and I and our different genes. I have multiple type 2 diabetics in my immediate family and as I entered my 30s I had a difficult time controlling my weight and my sweet tooth went out of control. My wife has never had this issue. Once I learned how to control my blood sugar by controlling my diet, I was able to lose weight. Why? Humans can only shed pounds when insulin levels are low. So since eating too many carbs and sugars spiked my insulin levels (and did nothing to hers), no amount of exercise would let the pounds melt away. However, eating a diet that didn’t spike my insulin levels (low carb, low sugar), allowed the pounds to be worked off. However, as you’ll see, adding in too much caffeine is a real problem for people with my genes.
I’ve often told my wife that if I drank coffee like she did, I’d weigh 300 pounds. Why? Caffeine for me causes my body to over release insulin, which drops my blood sugar too low and makes me artificially ravenous. For her, it has no effect. I describe in our book, Orthopedics 2.0, how I didn’t learn what true hunger was like until I was in my 40s. Up until that time, I thought hunger was the feeling that you would gladly hold up a 7-11 for a candy bar, rather than the gnawing general sensation that you should eat. Coffee pushes my insulin levels high enough and my blood sugar levels low enough that there better not be a candy bar in my immediate vicinity.
At this point you’re likely thinking, but I’m not a diabetic, so this doesn’t apply to me. Well here’s a test to see if you and I share these ice age genes. If you had a hard time controlling your weight as you moved into your 30s and 40s, you likely share my crazy genes. First, you’re at very high risk for becoming a diabetic (you likely have a few in the family tree). If this happens, it will dramatically increase your chances of a being sick at a younger age and dying early. Second, Starbucks is getting you there quicker, just like gasoline at a bonfire. On the other hand, if you’ve never had a hard time controlling your weight and you only weighed a bit more at 40 than you did at 20, you likely share some of my wife’s genes. For you, your trips to Starbucks may be a net positive.
The upshot? Did you ever wonder why they sell lots of sweets at Starbucks and many of their drink concoctions are very sweet? Now you know. Mark my words, once we get to the level of sophistication in large studies where each study participant’s genes are measured and known (maybe ten years from now), we will find that for some of us, caffeine is a ticking time bomb, and coffee is dangerous. For others it’s a great way to wake up and may stave off dementia. However, if you share my ice age genes, Starbucks is likely slowly killing you by pushing you towards that diabetic cliff.