Welcome to Straight Talk on Health, I’m your host Dr. Chet Zelasko. Together with WGVU in Grand Rapids MI, I examine the world of health and health research. Whether it’s research that makes the news, another miracle diet, or a new food fad, I look at the science behind them, and let you know whether it’s real or not. You can check out other things that I do on my website Drchet.com and sign up for my free emails.
In one of the first jobs I ever had, the foreman would pour a half-cup of coffee and fill the rest up with water; he’d had a heart attack and his doctor told him to limit his coffee intake. Fifty years later, many physicians still recommend that people avoid coffee if they have high blood pressure or had a cardiac event such as a heart attack. The thought was and is to lower the stimulating effect of caffeine to keep heart rate and blood pressure lower. In the interim, some studies showed that coffee contributes to cardiovascular disease in some way and more recently, that it may not. So if you love coffee the way I love coffee, you may be encouraged by a couple of recent studies--all the while realizing that a couple of studies are not overwhelming evidence.
The first study was published in the New England Journal of Medicine in March of 2023. (N Engl J Med 2023;388:1092-100). Researchers examined the effect of coffee on heart rhythms in 100 subjects with a mean age of 39. The subjects served as their own controls. All subjects had a variety of blood tests as well as genetic tests to determine if they were fast or slow processors of caffeine. A little more about the genetics later. They also wore a new-age heart rhythm monitor for the 14 days of the study. I’ve worn that monitor. It gives accurate EKGs to monitor heart rate and heart rhythm abnormalities such as premature atrial contractions and atrial fibrillation.
The subjects were notified the evening before whether they were going to be on a two-day coffee drinking cycle or two-day caffeine avoidance; the idea was to track immediate impacts, Not long term effects. The good news: there were no differences in abnormal rhythms on coffee days versus non-caffeine days and no impact of caffeine processing. One interesting observation: on the days subjects drank coffee, they walked more steps. Did the caffeine in coffee caused them to have more energy and thus just walk more steps? The study didn't address that issue.
I think it's important to understand that coffee is not just about its caffeine content. It is a plant with a bean that contains over 1000 phytonutrients. Some of those fighter nutrients are being examined for potential benefits in the lungs and other organs in the body. Caffeine is just one of those nutrients. So while there is no question that caffeine does have a stimulatory effect, especially on the CV system, we have to understand there is a difference between drinking coffee and having an energy drink or a soda that has had caffeine added to it. Let's look at another study.
“Coffee consumption and associations with blood pressure, LDL‐cholesterol and echocardiographic measures in the general population is the title of a study published in the journal Nature in March of 2023. (Nature, Scientific Report. (2023) 13:4668.
Researchers in Germany used a unique approach in the Hamburg City Health Study: they selected the first 10,000 volunteers for these study and divided them into coffee drinkers and non-coffee drinkers. The subjects for the health study who didn’t drink coffee were eliminated from the study, so they ended up with 9,009 subjects. Is in Hamburg, just over 90% of the people drink coffee, at least One Cup per day
The researchers collected dietary data along with a variety of other demographic and physiological variables, integrating lifestyle-related behavior like smoking and exercise, comorbidities such as having present CVD or T2D, biomarkers like serum lipids and abnormal heart rhythms, electrocardiographic and echocardiographic data, and finally major cardiovascular diseases (CVDs). They divided up the subjects by coffee intake: low = less than three cups a day, medium = three or four cups per day, and high = more than four cups of coffee per day.
Here are the major findings.
This epidemiological cross-sectional study showed that:
High coffee consumption correlated with slightly higher LDL cholesterol. I was surprised it did not raise serum TG as caffeine can stimulate their release. However, this was not a randomized controlled trial so they dictate when they should and should not drink coffee. They just tested their levels after an overnight fast.
Moderate and high coffee consumption correlated with lower systolic blood pressure and lower diastolic blood pressure
Different levels of coffee intake didn’t impact heart rhythms or function
Most important, coffee intake did not impact the presence of CVD nor prior cardiac events such as heart attacks and heart failure.
Were the results of coffee and LDL cholesterol concerning? No—the difference was just five mg/dl, well within measurement error.
That begs the question: Is Coffee Safe to Drink? Here's what I think.
Coffee was always safe to drink; the question was how our bodies responded to consuming it. Neither of these studies was perfect, but they show that even high coffee consumers, including myself, may not be at any significant risk for promoting or advancing CVD or cardiovascular events.
I think for most people, coffee and caffeine are closely linked. Let me repeat what I said earlier in a slightly different way, relying on a quote from the Hamburg researchers: Most of us don’t realize that coffee is a complex liquid, consisting of more than 1,000 bioactive substances, including phytochemicals that have proven beneficial for many organ systems; it’s not only a nervous system stimulant because of the caffeine content. What we can't always predict this is how it will affect an individual.
Let me tell you a quick story about a young man in my toastmasters group. He decided, after reading about coffee and caffeine, to do a little self-examination. He noted that when he drank too much coffee with maybe an energy drink or two thrown in, he would start to feel a little jittery, he didn't sleep as long, and on those days when he really overdid the coffee intake, he felt his heart flip flopping as he described it. So he wanted to see what would happen if he cut back on his coffee drinking.
What's interesting is that he didn't try to quit cold. For a week or two he decreased his intake by 1 cup per day. Then the next time. By another cup. After decreasing intake by that amount, the heart flip flopping had disappeared, he felt more calm, and he started sleeping a little bit longer although by his own admission he hated getting up in the morning anyway. After about 90 days, he was down to 1 cup per day and he had that cop about 90 minutes after waking up in the morning. Now given that this was a speech where he was supposed to research a topic he was not familiar with, he did a very good job. He had found someone who suggested that your circadian rhythms don't finish until 90 minutes after you wake up the next morning and so he decided to follow that pattern. Whether that's true or not is not the purpose of this podcast. However, a responsible approach to changing his lifestyle is always what I'm about. So after the self examination, he feels better and he knows exactly how coffee and the caffeine it contains impacts his health. I think it's a good lesson for any of you listening on how to change your diet or your exercise level or even your sleep patterns. My experience is that people who like numbers, and he is a financial planner, do well in tracking things and I think that that assisted him in his quest to find out how coffee impacted his health.
So what's the bottom line? When it comes to coffee, I think it’s person-specific. Remember I said that there is a genetic component to processing caffeine? Some people genetically process caffeine quickly while others process it slowly. What that means is someone like myself can drink coffee in the 30 minutes before bed and fall right to sleep while others would not be able to sleep at all during the night. That's why I say, Taste aside, some people may process caffeine differently, which may impact how much coffee someone could enjoy. These studies add to a body of work which shows that coffee is safe for the heart and other organs; other benefits or issues require further study. For me, time for another mug of Sumatra Roast, my favorite roast that's all the time we have for this show remember, health is a choice. Choose wisely today and every day. I'm Dr. Chet Zelasko.
