1. Long-term plant-based diet was associated with more variance in microbial structure and future cardiometabolic biomarkers, suggesting a possible protective role

Evidence Rating Level: 2 (Good)

Plant-based dietary pattern is gaining increasingly more attention from both the scientific community and general public. Prior research suggests that plant-based foods are associated with lower risk of cardiometabolic diseases, such as obesity, cardiovascular disease, and type 2 diabetes, and lower risk of cardiovascular mortality. Gut microbiota provides a key connection between diet and metabolic health. It is unclear how plant-based dietary pattern may influence gut microbiota profiles. Hence, this study aimed to examine the associations of long-term habitual plant-based dietary pattern with gut microbiota profiles in a population-based prospective cohort study in China. A total of 3096 participants from 15 provinces across China were included. A healthful plant-based diet index (hPDI), unhealthful plant-based diet index (uPDI), and overall plant-based diet index (PDI) were created. The average PDIs were calculated using repeat food frequency questionnaires (FFQs) collected in 2011 and 2015, representing a long-term dietary pattern. In 2015, 3-day 24-hour dietary recalls were collected to estimate a short-term dietary pattern. Fecal samples were collected and measured using 16S rRNA sequencing. The association of long- and short-term plant-based dietary patterns with gut microbial diversity were investigated. There was a significant association between short-term hPDI and microbial alpha-diversity. Long-term plant-based diet was correlated with more variance in microbial overall structure. Only microbes related to long-term estimates showed association with future cardiometabolic biomarkers. These findings may offer insights into the protective role of long-term plant-based dietary pattern for cardiometabolic health.

Click here to read the study in BMC Medicine

Relevant Reading: Influence of diet on the gut microbiome and implications for human health

In-Depth [Prospective Cohort Study]: The present study was based on data from the China Health and Nutrition Survey (CHNS). To examine the relationship between the long-term plant-based dietary pattern and gut microbiome, 3096 adult participants who completed FFQs were included. To link short-term plant-based dietary pattern with gut microbiome, 3066 participants who completed 3-day 24-hour dietary recalls during stool sample collection were included. A hPDI, uPDI, and overall PDI were calculated based on 15 food groups. Healthy plant food groups included whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and potatoes, while less healthy plant food groups included refined grains, beverages and fruit juices, and sweets and desserts. Animal food groups included eggs, meat, animal oils, dairy, and fish or seafood. Stool samples were used for microbial DNA extraction and paired-end 16S rRNA gene sequencing and subsequently, taxonomic and functional profiles were generated. Statistical analyses included linear regression. In 2015, the mean (± SD) PDI were 45 ± 5 and 46 ± 6 for long-term diet and short-term diet, respectively. Participants with a higher long-term or short-term PDI score were less likely to be smokers or alcohol drinkers. Long-term PDIs and all 15 constituent food groups were significantly correlated with corresponding short-term estimates (p < 0.05). The correlation coefficients were 0.26, 0.28, and 0.22 for PDI, hPDI, and uPDI, respectively. Higher short-term hPDI was associated with higher Shannon’s diversity index and Pielou’s measure of species evenness. However, no statistically significant association was seen between the long-term PDIs and microbial alpha-diversity. Furthermore, the association between long-term PDIs and microbial beta-diversity was stronger than short-term PDIs. Four gut microbial features (Shannon’s diversity index, observed features, Peilou’s measure of species unevenness, and Faith’s phylogenetic diversity) of long-term plant diet were significantly associated with future fasting cardiometabolic risk biomarkers, including fasting insulin, HDL-C, LDL-C, TG, and CRP. However, gut microbial features related to short-term dietary estimates showed no significant association with future cardiometabolic risk biomarkers. These results provide information regarding possible associations between diet-related gut microbial features and cardiometabolic health.

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