digest
Introduction
On one hand, most health agencies consider oats a health food. And yet, on the other hand, you have social media influencers, including some doctors, that claim that oats are a detriment to our health. It's odd. In the end, the only thing that matters is what the data says. And what would be even more compelling is if the data came from several studies, not just one.
So, we covered the impact that oats, including oatmeal, has on cardiovascular disease. But there's much more to this story because oats have been recently discovered to impact our heart through an unexpected mechanism. Before we get into that mechanism, let's remind ourselves of the impact that oats have on our heart health.
Oats: Eat 'em or Leave 'em?
Specifically, if you look at the studies like this one that correlate oatmeal consumption with the risk of having coronary heart disease, we can see the relationship outlined in the data. If the lines go down from the horizontal dotted line, that indicates reduced risk. Now, the horizontal axis is the amount consumed. So clearly, while the data is limited to only going up to one serving per day consumed, there seems to be a dose response relationship. That's to say, eating half a serving of oatmeal per day is better than none, but eating a whole serving is better than half.
We see those kinds of relationships repeated in other studies as well, including looking at overall oat consumption. And I want to emphasize because I'm aware that some people hear the word correlate and get activated into a sleeper agent to put a hit out on studies claiming the tired correlation is not causation. These studies also adjust for many factors including other aspects like nutrition, physical activity, and much more. But we also won't be relying on these correlation studies alone either. The takeaway right now is that oats and oatmeal are linked to reduced risk of heart disease.
Now what's often described in these studies is that the main mechanism by which oats offer this heart disease protecting effect is through reductions in blood cholesterol levels. More specifically, having an overabundant amount of cholesterol containing particles called lipoproteins leads to more being trapped in the arteries, therefore causing plaque to begin forming. Obviously, this is something very easy to verify because we have many randomized control trials that test it. Just as one, we can see the change in these cholesterol containing lipoproteins right here. The blue is the control condition and the orange is the oatmeal condition. If the violin plots drop down from the starting zero there, that means a reduced lipoprotein cholesterol. And that's what we find compared over time as well as between groups.
But the thing that troubles me with this kind of work is that we're only looking at a mediator, which means that we're just inputting oats into the diet and then measuring something that is involved in heart disease. None of this tells us exactly how oats are having this effect. And that's where this unexpected mechanism comes into play, coming out of this new study. Now, what if we extend things to whole grains, not just oats? Or even if we stick to oats, are there cancer benefits, too? I have all of that in my full main analysis, the one available for the Physionic Insiders. If you're so inclined to learn more and want access to other analyses with applicable takeaways, then check out the Physionic Insider membership. You get videos, articles, podcasts, live sessions with me, and much more. I work on it every day. The link to check out the Physionic Insiders is in the description. I'll see you there.
The Traditional
The idea was that oats might be having these effects through not just the traditional understanding of fiber in oats. The traditional mechanism was that oats contain a molecule, a fiber called beta-glucan. And that beta-glucan, because it is considered a viscous fiber, can physically block cholesterol reabsorption and increase bile excretion. Bile excretion is important because the liver dumps cholesterol already found in the body into bile and dumps it into the intestines to be pooped out. In addition, the loss of bile means that the liver has to produce more. And as bile is made up of cholesterol, it creates a cholesterol sink, allowing the cholesterol to go somewhere other than the blood.
Something Suspicious about Oats…
This study attempts to add to that classic understanding and claims that oats contain molecules beyond beta-glucan fibers. These molecules are phenolic compounds found in oats. Specifically, it argues that when we consume oats, they get digested. The free molecules, the phenolic compounds, interact with our gut microbiome and the bacteria in our intestines, which then convert them into new molecules. These new molecules then get absorbed into our bloodstream, interact with our liver cells, and cause this cholesterol-lowering effect.
Beyond that, oats seem to have a direct effect at changing our microbiome. There were significant reductions in microbes linked to worse health outcomes and larger numbers of microbes linked to better health outcomes. It's also important to note that this main study that we've been going over looked at oat consumption in the short term and in the long term, so over weeks, and identified different effects of oats based on the time and dose. The microbiome changes, for example, are prominent in the short term and they remain present, just less pronounced in the long term. In addition, some of the harmful associated microbes didn't truly fall in number until several weeks of oat consumption. So, the point being that it needs to be a long-standing habit of consumption.
I will readily admit, which I've detailed more in my extended video, that I was unimpressed with some of the data and disagree with the interpretations of the researchers on some of the mechanisms that they describe. But these microbiome shifts are also characterized in other studies. This all means that eating oats is linked to reduced risk of cardiovascular disease. It also means that some of the explanation, though maybe not all, is through this reduced blood cholesterol containing lipoproteins found in the blood. We also know now that oats shift our microbiome over the long term to a more beneficial profile. However, there are still several aspects that need to be fleshed out.
I think now the amount to consume is based on a stitching of these randomized control trials and the much larger associative studies that we went over, including some from my previous analysis. I'd guess that the amount to consume to affect positive cardiovascular changes is around 75 grams or more of dry oats, two or more times per week, with possibly greater benefits consuming more than twice per week. If you're interested in considerations of processing of oats and some additional nuances as it relates to heart disease, be sure to check out my main analysis, which is right here.
While I did find certain aspects of the presented data to be disappointing, I think that it's cool to know that eating oats can meaningfully change our microbiome. I hope you can agree. I'll catch you in the next one. See you.