Reviewed by Dietitian Jessica Ball, MS, RD
Photographer: Ali Redmond. Design EatingWell.
Key points
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Eating oatmeal may help lower cholesterol in people with metabolic syndrome.
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The study suggests that the gut microbiome may help create the benefit.
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Adding oatmeal to your diet can be a practical strategy to support heart health.
If your doctor has mentioned that your cholesterol levels could use some work, you’re not alone. Nearly 10 percent of U.S. adults have total cholesterol levels above recommended limits, and many are looking for dietary changes that can make a real difference. You’ve probably heard that oatmeal is good for your heart, but new research suggests that its benefits go beyond what we previously understood—and your gut bacteria may deserve some of the credit.
A new study published in Communication of nature found that eating oatmeal can significantly reduce LDL (“bad”) cholesterol levels in just two days, with reductions of about 10% in people with metabolic syndrome. Even more surprisingly, researchers found that much of this benefit comes from compounds produced when your gut microbiome breaks down the oats you eat.
If you’ve been wondering whether it’s worth adding more oatmeal to your routine—or how much you should eat to see results—this study offers some compelling answers. Here’s what the researchers found and how you can put it into practice.
How was this study conducted?
Researchers at the University of Bonn in Germany conducted two randomized controlled dietary interventions involving a total of 68 adults with metabolic syndrome – a group of conditions that include central obesity, high blood pressure, high blood sugar and abnormal cholesterol levels. All participants were between 45 and 70 years old.
In the first study, 32 participants were randomly assigned to either a short-term, high-dose oat diet or a control diet for two days. Those in the oat group ate three meals of oats daily, each containing about 100 grams (about 1 cup) of rolled oatmeal—a total of 300 grams per day. The control group ate combined macronutrient meals without oats. The oat group was followed for an additional six weeks as they returned to their normal diet.
In the second study, 34 participants were assigned to either replace one meal a day with one meal of oats (80 grams of oatmeal) or to continue their usual Western diet for six weeks. The researchers collected blood and stool samples to analyze cholesterol levels, gut bacteria composition, and metabolomic profiles—essentially, measuring which metabolites were circulating in the participants’ bodies.
What did the study find?
The results were particularly striking for the short-term, high-dose oat diet. After just two days, participants in the oat group experienced significant reductions in both LDL (“bad”) cholesterol (about 10%) and total cholesterol (about 8%) compared to the control group. Perhaps even more interestingly, cholesterol levels tended to remain below baseline during the six-week follow-up period, even after participants returned to their usual diet.
Both oat interventions resulted in increased levels of ferulic acid, a phenolic compound found in oats, in participants’ blood. The high-dose oat diet also increased dihydroferulic acid, a metabolite produced when gut bacteria break down ferulic acid. This is significant because researchers have found strong associations between these microbially produced phenolic compounds and lowering cholesterol levels.
The six-week moderate oat diet showed milder effects. Although it increased some phenolic metabolites and appeared to stabilize cholesterol levels, it did not produce the same dramatic cholesterol reductions as the short-term, high-dose approach. The researchers suggest that this may be because individual differences in the composition of gut bacteria and dietary habits play a greater role when oat consumption is more moderate.
It is worth noting that this study had a relatively small sample size, which means that the results should be confirmed in larger studies. Participants were mainly Caucasian adults in Germany, so the findings may not apply to all populations. Additionally, some dietary information was self-reported, which always leaves room for error.
How does this apply in real life?
If you’re looking to support your heart health, these findings suggest that oatmeal may be an even more powerful tool than we realized, especially when eaten in larger amounts. While eating 300 grams of oatmeal daily (the amount used in the high-dose study) isn’t practical for most people long-term, the study suggests that periodic oat-focused days could be a useful strategy for people looking to improve their cholesterol levels.
Here are some practical ways to include more oats in your routine:
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Start your day with oatmeal. A bowl of oatmeal for breakfast is one of the easiest ways to increase your intake of oats. Try topping it with berries, nuts or a drizzle of honey for added flavor and nutrition.
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Add oats to smoothies. Mixing ¼ cup of oatmeal into your morning smoothie adds fiber and helps you feel fuller for longer.
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Use oat flour in baking. Swap all-purpose flour for oat flour in muffins, pancakes or homemade bread.
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Try overnight oats. If you’re short on time in the morning, prepare overnight oats the night before for a grab-and-go breakfast.
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Consider periodic high-oat days. Based on this study, occasionally eating several oat-based meals in a single day can provide a cholesterol-lowering boost—you could try a fruit smoothie with oats in the morning, then opt for savory oats like Sriracha, Egg & Avocado Overnight Oats for lunch.
This study also highlights the importance of gut health to heart health. The phenolic compounds that helped lower cholesterol were largely produced by gut bacteria, so nurturing a healthy gut microbiome can amplify the benefits of eating oats. To support your gut bacteria, focus on eating a variety of high-fiber foods and fermented foods like yogurt, while limiting ultra-processed foods.
Our expert
A new study published in Communication of nature found that eating oatmeal can help lower cholesterol levels, and the benefits appear to be driven in part by the phenolic compounds your gut bacteria produce when they break down the oats. A short-term high-oat diet lowered LDL cholesterol by about 10% in people with metabolic syndrome, while a moderate daily intake of oats helped keep metabolic markers stable over six weeks. These findings add to the evidence that oatmeal is a heart-healthy food choice and suggest that your gut microbiome plays an important role in how your body benefits from oats. Adding oatmeal to your diet is an easy way to support your cardiovascular health.
Read the original article on EatingWell