July 9, 2026, 6:27 pm | Read time: 4 minutes
The gut flora has been a focus of heart research for several years. It influences inflammation processes and metabolism, and could therefore also affect the course of cardiovascular diseases. A new study examined whether a diet that supports gut flora is associated with better survival chances in people with coronary heart disease.
Gut-Friendly Diet Linked to Lower Mortality Risk
Researchers investigated whether a gut-friendly diet is associated with a lower mortality risk in people with coronary heart disease. The gut flora includes billions of microorganisms that can influence inflammation, fat metabolism, and blood vessel function.
The result was that patients with a particularly gut-friendly diet had a significantly lower risk of dying during the observation period. The connection was especially evident from a certain value of the so-called “Dietary Index for Gut Microbiota” (DI-GM).
How the Study Was Conducted and What It Examined
For the study, scientists analyzed data from 1,537 adults with coronary heart disease from the U.S. health study NHANES. Participants were recorded between 2005 and 2018 and followed up until the end of 2019.1
Using a 24-hour dietary record, researchers calculated the DI-GM for each participant. This index evaluates how beneficial the diet is for the gut flora. The higher the value, the more the diet supports the gut microbiome according to this rating system. For the analysis, scientists divided participants into four groups with DI-GM values of 0 to 3, 4, 5, and at least 6 points.
Positively rated are fiber, whole grains, fermented dairy products, coffee, green tea, and various plant-based foods. Conversely, red and processed meat, refined grains, and a high-fat diet are less favorable.
Subsequently, scientists compared mortality between participants with different DI-GM values. In the analysis, they considered numerous other factors, including age, gender, smoking, alcohol consumption, body weight, high blood pressure, diabetes, and various lab values.
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The median age of participants was 68 years, with about two-thirds being men. During the follow-up period, 37.4 percent of study participants died.
When the DI-GM was evaluated as a continuous value, the association with mortality was no longer statistically clear after considering all influencing factors. However, when comparing individual DI-GM groups, a clearer picture emerged: Participants with a DI-GM value of 5 had a 40.7 percent lower mortality risk than those with the lowest values. With a DI-GM of at least 6, the mortality risk was 35.1 percent lower. The results thus suggest a plateau effect: From a DI-GM of about 5, most of the protective effect seems to be achieved. Paradoxically, an even more gut-friendly diet was rather disadvantageous for mortality risk. Experts call this phenomenon the “plateau effect.”
A significant advantage only appeared from a certain DI-GM value. Moreover, the association persisted in most patient groups studied. It was somewhat different for diabetics. A gut-friendly diet was also associated with a lower mortality risk for them, but the potential protective effect was less pronounced than for non-diabetics. This suggests that the metabolic disorder could influence the relationship between diet and mortality risk.
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What This Specifically Means
The results suggest that a diet supporting gut flora could be associated with a lower mortality risk in people with coronary heart disease. As a possible explanation, the authors mention that fiber-rich and plant-based foods promote the growth of beneficial gut bacteria. These produce substances that can reduce inflammation and support blood vessel health.
It was also notable that the association was more pronounced in people without diabetes than in patients with diabetes.
Study Context and Possible Limitations
The authors point out that the association between a gut-friendly diet and mortality in patients with coronary heart disease has been scarcely studied. The analysis is based on a large, representative health study from the U.S. Additionally, researchers considered numerous factors such as age, smoking, diabetes, or high blood pressure that could influence the results.
However, the study also has limitations. As an observational study, it cannot prove that the diet is actually the cause of the lower mortality risk. Moreover, the diet was recorded on only one day, so it may not fully reflect long-term eating habits.