By Joseph E. Scherger, MD, MPH

Core Faculty, Eisenhower Health Family Medicine, Residency Program, Eisenhower Health Center, La Quinta, CA; Clinical Professor, Keck School of Medicine, University of Southern California, Los Angeles

Dr. Scherger reports no financial relationships relevant to this field of study.

SYNOPSIS: A randomized, multicenter study showed that eating a Mediterranean diet for one year improved the diversity of the gut microbiome in older subjects and was associated with reduced frailty and better health.

SOURCE: Ghosh TS, Rampelli S, Jeffery IB, et al. Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. Gut 2020; Feb 17. pii: gutjnl-2019-319654. doi: 10.1136/gutjnl-2019-319654. [Epub ahead of print].

This study was based at a Microbiome Institute in Cork, Ireland. The authors profiled the gut microbiota of 612 non-frail or pre-frail elderly subjects from five European countries: the United Kingdom, France, Netherlands, Italy, and Poland. The randomized study group was placed on a standardized Mediterranean diet that has been used in other European studies.1,2

The microbiota initially reflected both the diets of the participants and the countries where they lived. After one year, the microbiota of those on the Mediterranean diet became more diverse among the intervention group on the diet, regardless of country. The control group remained on their standard diet.

Besides improving the diversity of the microbiome, the study group showed improvements in markers of frailty, including hand strength, walking speed, and cognitive function. The more diverse microbiome also was associated with fewer inflammatory markers, including C-reactive protein and interleukin-17. The more diverse microbiota in the intervention group produced more short-chain fatty acids that have been associated with better health. Conversely, the microbiome diversity decreased in the control group, with an increase in detrimental effects such as insulin resistance and fatty liver disease.


Microbiome science still is in its infancy, and this observational study is compelling. However, this work does not establish cause and effect. The expression “we are what we eat” has been conveyed in different ways for centuries. A revision of this concept would be “we are what we feed our microbiome.”

Recently, Mark Hyman, MD, has explored the many problems of the modern Western diet, loaded with sugary carbs and overly processed foods.3 Too many Americans (and plenty of others around the world) carry excess body fat; there’s a good chance many in this group are at least prediabetic. We have been poisoning ourselves, including the “gut bugs” that protect us. There are healthy culinary alternatives, and the Mediterranean diet is a clear winner. Every clinician should consume a healthy diet and be able to recommend one to all patients. That way, we become agents for good health, including among the frail elderly.


  1. Marseglia A, Xu W, Fratiglioni L, et al. Effect of the NU-AGE diet on cognitive functioning in older adults: A randomized controlled trial. Front Physiol 2018;9:349.
  2. Santoro A, Pini E, Scurti M, et al. Combating inflammaging through a Mediterranean whole diet approach: The NU-AGE project’s conceptual framework and design. Mech Ageing Dev 2014;136-137:3-13.
  3. Hyman M. Food Fix: How to Save Our Health, Our Economy, Our Communities, and Our Planet — One Bite at a Time. New York: Little, Brown Spark; 2020.