Introduction

Coronary heart disease (CHD) remains one of the leading causes of morbidity and mortality worldwide, accounting for a substantial proportion of cardiovascular disease (CVD)-related deaths. In 2015, approximately 111 million of the 400 million global CVD cases were attributed to CHD, and the World Health Organization projects CHD to remain among the three leading causes of death globally by 2030, with an estimated 9.3 million annual deaths.^1-2 The development and progression of CHD are influenced by both non-modifiable factors, including age, sex, and genetic predisposition, and modifiable factors such as hypertension, diabetes mellitus, dyslipidemia, obesity, smoking, physical inactivity, and poor dietary habits.^3-5 Among these, dietary modification represents one of the most effective preventive strategies for reducing cardiovascular risk and improving long-term outcomes.⁶

Gut microbiota and coronary heart disease

Growing evidence has established the gut microbiota as an important regulator of cardiovascular health. The intestinal microbiome influences lipid metabolism, glucose homeostasis, immune regulation, and vascular function through the production of bioactive metabolites. Beneficial metabolites such as short-chain fatty acids (SCFAs), generated from dietary fiber fermentation, exhibit anti-inflammatory properties, improve endothelial function, and maintain intestinal barrier integrity. Conversely, microbial metabolism of dietary choline and L-carnitine produces trimethylamine (TMA), which is subsequently converted into trimethylamine-N-oxide (TMAO), a metabolite strongly associated with atherosclerosis, endothelial dysfunction, platelet activation, and adverse cardiovascular events.^7-11 These findings highlight the gut microbiota as a critical mechanistic link between dietary intake and CHD progression.

Dietary patterns and gut microbial health

Diet is one of the most influential determinants of gut microbial composition and diversity. Diets rich in dietary fiber, fruits, vegetables, legumes, and whole grains promote the proliferation of beneficial bacterial species and increase SCFA production, whereas diets high in saturated fat, processed meat, and refined carbohydrates contribute to gut dysbiosis and systemic inflammation. The Mediterranean diet, characterized by high consumption of plant-based foods, olive oil, fish, and nuts, has consistently demonstrated cardiovascular benefits by improving lipid profiles, reducing insulin resistance, lowering blood pressure, and attenuating chronic inflammation.^12,13 Recent studies suggest that many of these cardioprotective effects are mediated through favorable alterations in gut microbiota composition and metabolic activity.¹⁴Consequently, evaluating dietary quality based on its influence on gut microbial health has become an emerging area of cardiovascular nutrition research.

Dietary index for gut microbiota (DI-GM)

The DI-GM is a recently developed dietary assessment tool that evaluates diet quality according to its potential effects on gut microbiota. The index incorporates 14 dietary components, including foods and nutrients known to either promote or adversely affect microbial diversity and function. Beneficial dietary components receive higher scores when intake exceeds sex-specific median values, whereas adverse dietary components receive lower scores when intake is excessive. The cumulative DI-GM score ranges from 0 to 14, with higher scores indicating dietary patterns more favorable for maintaining healthy gut microbiota. Unlike conventional dietary indices that primarily evaluate nutritional adequacy, DI-GM specifically captures the interaction between diet and intestinal microbial ecology, making it a promising tool for assessing diet-related cardiovascular risk.¹⁵

Association between DI-GM and mortality in CHD

Recent evidence has demonstrated a significant association between higher DI-GM scores and reduced all-cause mortality among patients with CHD. In a retrospective cohort study utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2005–2018, 1,537 adults with CHD, representing approximately 8.1 million U.S. adults, were evaluated to determine the relationship between DI-GM and mortality. During follow-up, the overall all-cause mortality rate was 37.4%. Participants with DI-GM scores ≥6 exhibited a 40.7% lower risk of all-cause mortality compared with those scoring 0–3 (hazard ratio [HR] 0.593; 95% confidence interval [CI] 0.413–0.851), while individuals with a score of 5 had a 35.1% lower mortality risk (HR 0.649; 95% CI 0.432–0.975). Restricted cubic spline analysis further demonstrated a nonlinear inverse association between DI-GM and mortality, indicating that mortality risk progressively decreased with increasing DI-GM scores. Interestingly, subgroup analyses suggested that diabetes mellitus significantly modified this association, implying that individuals with diabetes may derive greater survival benefits from diets supportive of gut microbial health.¹⁵

Clinical implications and future perspectives

The emerging evidence supporting DI-GM highlights the importance of integrating gut microbiota-targeted nutritional strategies into cardiovascular care. Since dietary modification is a cost-effective, non-pharmacological intervention, incorporating DI-GM into routine nutritional assessment may facilitate individualized dietary counseling for patients with CHD. Furthermore, DI-GM may serve as a useful prognostic marker for identifying high-risk patients who could benefit from intensive lifestyle interventions. Nevertheless, current evidence is largely observational, and prospective cohort studies and randomized controlled trials are needed to establish causal relationships and determine whether improving DI-GM scores through dietary intervention directly reduces cardiovascular mortality.

Conclusion

The DI-GM represents a novel approach to evaluating dietary quality by considering its influence on gut microbial composition and function. Current evidence suggests that higher DI-GM scores are significantly associated with lower all-cause mortality among patients with coronary heart disease, potentially through mechanisms involving reduced inflammation, improved endothelial function, enhanced SCFA production, and decreased TMAO synthesis. Although further longitudinal and interventional studies are warranted, DI-GM has considerable potential as a practical nutritional biomarker for improving cardiovascular risk stratification and guiding personalized dietary interventions in patients with CHD.

References

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