“Novel Dietary Index for Gut Microbiota (DI-GM) linked with Lower Risk of Constipation”
Background
Different dietary patterns are associated with alterations to the gut microbiota and frequency of bowel movements. High-fibre fruits,vegetables and wholegrains are generally recommended to support microbial diversity and alleviate constipation, while the high fat, high sugar, processed foods typical of a Westernized diet are associated with gut dysbiosis..
The Dietary Index for Gut Microbiota (DI-GM) is an innovative classification tool designed following meta-analysis of 106 studies assessing the association between different foods and gut microbiota composition. It includes 14 dietary elements shown to significantly affect the gut microbiota. Influenced by the Mediterranean Diet Score and the Healthy Eating Index-2015, it includes 10 foods with beneficial effects on the microbiota (cranberry, chickpeas, avocado, broccoli, coffee, fermented dairy products, fibre, green tea, soybean, and wholegrains) and 4 with unfavourable effects (refined grains, processed meat, red meat, and high fat).
Method
Data were gathered from 3 consecutive cycles of the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2010. Researchers analysed information from 11,405 eligible participants who were >20 years old and experiencing constipation defined as <3 bowel movements a week.
Self-reported potential confounding variables were gathered. These included sex, age, marital status, race, poverty income ratio, education level, physical activity, smoking and alcohol status, BMI, and diagnosis of cardiovascular disease, diabetes, hypertension, and depression.
Results
After adjusting for all covariates, the results showed an 18% drop in the rate of constipation for each single point rise in the DI-GM score.
The prevalence of constipation decreased significantly as the intake of foods favourable to the gut microbiota increased.
DI-GM scores >6 demonstrated a 52% lower risk of constipation.
Subgroup analysis by age, sex, and diagnosis of cardiovascular disease, hypertension, diabetes, or depression revealed no statistically significant interactions. The association between DI-GM and constipation was relatively stable in every subgroup.
Conclusion
Greater intake of foods favourable to the gut microbiota is associated with a lower rate of constipation, even when accounting for other potential confounding variables such as age, sex, and physical activity levels.
Key Clinical Takeaways
Whilst the DI-GM has been researched in various contexts since its publication last year, this is the first study to demonstrate an association between the DI-GM and constipation. It adds weight to the growing body of evidence exploring the relationship between gut microbiota and digestive health. While there are limitations to this study (e.g. lack of microbiota analysis) and to the DI-GM (e.g. lack of data on the individual effects of each food), the results support nutritional strategies that focus on diversity, fibre, polyphenols, prebiotics, and fermented foods for promoting bowel regularity and a healthy microbiome.