According to a large-scale randomized controlled trial, the green Mediterranean diet (MED) has a striking effect on the microbial population of our gut microbiome. The DIRECT-PLUS trial found that the gut microbiomes of green MED dieters were enriched with bacteria known to have a significant effect on body weight and blood sugar control.
The novel analysis revealed that the health-promoting effects previously attributed to the green MED diet are mediated by the changes in the gut microbiome.
What is the “green” Med Diet?
The DIRECT-PLUS trial research team was the first to introduce the concept of the green-Mediterranean diet. This modified Mediterranean diet is further enriched with dietary polyphenols and lower in red/processed meat than the traditional healthy MED diet.
On top of a daily intake of walnuts (28 grams), the participants consumed 3 to 4 cups of green tea/day and 100 grams (frozen cubes) of duckweed green shake/day. The aquatic green plant duckweed substituted meat intake at dinner; it is high in bioavailable protein, iron, B12, vitamins, minerals and polyphenols.
These findings may explain previously published beneficial effects of the green-MED diet that were observed in the DIRECT PLUS trial, including reducing fatty liver, improving LDL (“bad”) cholesterol, blood glucose control, inflammation and blood pressure and slowing age-related brain atrophy as compared to the traditional, healthy MED diet.
Related: "Green" Mediterranean diet may slow brain aging
Gut microbiome effects
The results showed that while all diets (traditional MED diet, green-MED diet, healthy diet guidelines) induced substantial changes to the gut microbiome community, the changes seen in the green-MED dieters were much more pronounced.
Interestingly, the beneficial changes in the gut of green MED dieters were attributed to the tendency of this novel diet to specifically affect the rare bacteria in the subjects’ intestines. This was possibly due to the fact that a prominent component of the diet, duckweed, is new to the Western palate, allowing usually concealed microbes to flourish under the new gut environment induced by the aquatic plant.
The green MED diet induced specific microbial changes, including enrichments in the genus Prevotella, a bacteria known for its positive effects on glucose metabolism and insulin sensitivity.
"These findings may strengthen our understanding regarding the significant cross-talk between our nutritional intake, the microbiome and clinical outcomes," said the lead researcher.
Source: Genome Medicine, March 10, 2022.
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