Is There a Link Between Skipping Breakfast and Heart Disease?
That Old Breakfast Adage
As a nutritionist, I was definitely trained to believe that eating three meals a day was a good idea, with extra importance given to breakfast. I mean who hasn’t heard the old adage about breakfast being the most important meal of the day. The curious thing about this sage advice is that I don’t actually follow it myself, not in the strictest sense of the word anyhow.
I practice intermittent fasting on most days, which for me means I eat within a window of time that is roughly between 10 AM to 4 PM with the caveat that I drink a cappuccino in the early morning hours. If you’re interested in intermittent fasting, be sure to check out this post.
Given my breakfast skipping ways, I was compelled to read an epidemiological (or epi for short) study published recently called Association of Skipping Breakfast With Cardiovascular and All-Cause Mortality. The study uses what’s known as NHANES data to examine the relationship between skipping breakfast and outcomes related to heart health like cardiovascular disease, heart disease, stroke and what gets dubbed all-cause mortality. That last bucket is a bit of a catch-all, but hey, we do all die of something someday.
Using an NHANES sample of 6,550 adults ages 40-75 years old, the researchers found that after adjusting for age, size and race/ethnicity, people who never consumed breakfast had a 75% higher risk of all-cause mortality than those who consumed breakfast daily. Well, “Eek!”
Digging into the Epi Data
When it comes to epi, researchers are looking at the presence or absence of associations in large data sets to see what variables may be related to one another by more than random chance alone.
In this case, they want to parse out any relationship between breakfast eating (or not eating as the case may be) and heart health. They want to not get bogged down in other factors that could in theory impact this relationship. These factors include things like marital status, family income level, smoking status, alcohol intake, physical activity and the like. The researchers also want to ‘control for’ dietary factors like caloric intake and healthfulness.
The 75% number that I mentioned earlier goes down to 17% when we use what’s referred to simply as Model 3 in the paper. It’s a more elaborate and perhaps more accurate model because it controls for more variables including total calorie intake and overall diet quality. So, a little less eek (!), but I’m still raising my eyebrow at that 17%.
Let’s look at stroke mortality. Again, we all die of something someday, so hang with me. In the data model controlling for as much as possible (Model 4), people who never eat breakfast are more than 3 times likely to die of stroke than those who eat breakfast every day. They also find that those who rarely eat breakfast have a 44% lower chance of dying from stroke compared to those who eat breakfast every day. Yes, that’s right - lower. The little wrinkle appears to be eating breakfast rarely versus never. And to complicate this little wrinkle, remember, the participants have been asked, “How often do you eat breakfast?” with no further specifics probed. The possible answers include ‘every day,’ ‘some days’, ‘rarely,’ ‘never’ and ‘weekends only.’ So, we don’t know the quantifiable difference between rarely and never as the interviewee was allowed to answer based on their own interpretation of the possible answers. In other words, an exact number, like: “I eat breakfast 2 days a week”, is not reported in these data. That means the little wrinkle remains.
A More Discerning Look
This study does suggest there may be something going on between skipping breakfast and heart health. It does not, though, tell us the nature of how to best characterize that apparent relationship. For instance, the following elements could be at play:
Late Night Snacking: It could be that breakfast skippers are also late night snackers, and it’s actually the late night snacking causing cardiovascular disease. If this were to be the case, then the advice to eat breakfast to improve heart health would not be too useful.
Definitions of Breakfast: Unclear and varying definitions of what constitutes a breakfast may be impacting these data results. Suppose some participants interpreted breakfast as a sit-down type meal complete with waffles and eggs, in which case they reported, “Oh, I never eat breakfast” when interviewed by the data collector. Or, suppose others heard the word breakfast and thought immediately of that protein bar eaten during their daily car commute, in which case they reported, “Oh, I eat breakfast every day.” The point here is the researchers were not defining what constitutes a breakfast for the interviewees. It was just a question of frequency - “How Often Do You Eat Breakfast?” and nothing more.
Healthy Diet Specifics: In order to control for diet (meaning: giving some statistical credit to those who eat healthier foods) the researchers used what’s known as the Healthy Eating Index (HEI) which ranks the quality of a person’s diet on a scale from 0-100. This HEI element was added into Models 3 and 4 in the paper, making them relatively more robust than Models 1 and 2. However, the lingering issue is there are no known specifics about any breakfasts eaten. What foods did a person actually eat, one serving or two, prepared with butter or olive oil, any OJ, how about 100% whole grain toast, how many slices. You get the picture. So many questions, and all without answers.
Some nutrition researchers and food policy makers that I know choose to mostly ignore epi data, in part because it looks at population-level associations and tries to draw conclusions which end up being more specific than the data really allow for. Personally, I find that epi data can point us toward a reasonable research path. We then need to take a closer look with more robust studies like clinical trials in order to figure out what’s really going on to the degree where dietary recommendations can be reasonably made.
These findings, in my opinion, suggest meal timing and meal patterns do impact cardiovascular health in some way. This can be a bad thing like maybe breakfast skipping does lead to stroke. Or, it could be a good thing, like eating breakfast, but only every so often guards against stoke. It depends, but would it be wise to ignore this study completely and not look further into the details? Probably not.
My suspicion is this breakfast/stroke association has less to do with the actual breakfast skipping and much more to do with the downstream behavioral factors that may be associated with breakfast skipping that weren’t recorded in this study.
Imagine a hurried, frazzled corporate worker who drinks black coffee first thing in the morning, with just a dash of creamer if there’s any in the fridge. The morning is just too busy to eat because the kids have to be shuttled to school in the rain and traffic always seems to be wretched thanks to road construction. Her first food of the day is typically during the 11 AM staff meeting where she has to report on whether or not she is hitting her weekly sales targets. It was also just announced that there will be no corporate bonuses this year. Well, sigh. This breakfast-skipping person might have heart issues that have nothing to do with skipping breakfast.