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Mediterranean Diet Modulates Human Gut Microbiota

by Lewis Chang, PhD

Gut microbiota, a community of trillions of microorganisms living in the gastrointestinal tract, play an important role in health and disease in humans. A loss in species richness and diversity in the microbiota has been associated with many metabolic disorders and disease states.1

Nutrition can have a significant impact on the microbiota composition. The Mediterranean diet is known for its various health benefits.2 However, little is known on how the Mediterranean dietary pattern affects the composition of the gut microbiota. Researchers from the Institute of Agrochemistry and Food Technology, Spanish National Research Council (Valencia, Spain), aimed to shed light on the effect of Mediterranean diet on gut microbiota, especially in healthy individuals.3

Twenty-seven healthy adults, some with normal body weight and some with elevated body mass index, participated in the study.3 Habitual dietary information was assessed using a validated food frequency questionnaire. Adherence to the Mediterranean diet was determined using a specific score (0 = minimal adherence and 14 = maximal adherence). Fecal samples were collected for microbiome analysis.

When evaluating the effect of adherence to the Mediterranean diet, they found:3

  • Higher adherence was associated with higher levels of short-chain fatty acids (an indication of a healthier gut microbiota)
  • Lower adherence was associated with a higher ratio of Firmicutes-Bacteroidetes (an increased ratio has been seen in individuals with metabolic disorders)

When evaluating the effect of specific dietary components, they found:3

  • Higher consumption of animal protein and saturated fat was associated with a lower microbial diversity
  • Higher consumption of simple sugars was associated with lower microbial richness
  • Higher consumption of plant-based nutrients was associated with higher bifidobacterial counts and higher levels of short-chain fatty acids

There is still much to learn from future studies on how to improve health and prevent disease via modulation of microbiota composition and diversity. Nevertheless, these findings3 illustrate that diet and gut microbiota are highly interconnected.

Why is this Clinically Relevant?

  • Diet, gut microbiota and human health are closely connected
  • Specific dietary components and dietary patterns associated with the Mediterranean diet may beneficially influence the gut microbiota composition and diversity

View the abstract


  1. Le Chatelier E, Nielsen T, Qin J, et al. Richness of human gut microbiome correlates with metabolic markers. Nature. 2013;500(7464):541-546.
  2. Dinu M, Pagliai G, Casini A, Sofi F. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. Eur J Clin Nutr. 2018;72(1):30-43.
  3. Garcia-Mantrana I, Selma-Royo M, Alcantara C, Collado MC. Shifts on gut microbiota associated to Mediterranean diet adherence and specific dietary intakes on general adult population. Front Microbiol. 2018;9:890.


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