Microbiome Discovery: You Are What You Eat … As a Child

Eating a poor diet as a child can alter one’s microbiome for life, even if one learns to eat healthier later in life, suggests a study published in the Journal of Experimental Biology. Granted it’s a mice study, but researchers at University of California Riverside showed a significant decrease in the total number and diversity of gut bacteria in mature mice fed an unhealthy diet as juveniles. There is one caveat, exercise may overcome some of the damage.

microbiome, childhood eating habits

“We studied mice, but the effect we observed is equivalent to kids having a Western diet, high in fat and sugar and their gut microbiome still being affected up to six years after puberty,” explained UCR evolutionary physiologist Theodore Garland.

As is well known, in a healthy body there is a balance of pathogenic and beneficial organisms, which stimulate the immune system, synthesize key vitamins and are central to the gut-brain axis. However, if the balance is disturbed, through the use of antibiotics, illness, or eating an unhealthy diet, the body could become susceptible to disease.

In this study, Garland’s team looked for impacts on the microbiome after dividing mice into four groups: half fed the standard, ‘healthy’ diet, half fed the less healthy ‘Western’ diet, half with access to a running wheel for exercise, and half without.

After three weeks spent on these diets, all mice were returned to a standard diet and no exercise, which is normally how mice are kept in a laboratory. At the 14-week mark, the team examined the diversity and abundance of bacteria in the animals. Here is what they found:

  • The quantity of bacteria such as Muribaculum intestinale was significantly reduced in the Western diet group. This type of bacteria is involved in carbohydrate metabolism.
  • Analysis shows that the gut bacteria are sensitive to the amount of exercise the mice got. Muribaculum bacteria increased in mice fed a standard diet who had access to a running wheel and decreased in mice on a high-fat diet whether they had exercise or not.
  • This latter finding supports previous research showing an increase in a highly similar bacteria species, which was enriched after five weeks of treadmill training. This suggests that exercise alone may increase its presence.
  • Overall, the UCR researchers found that early-life Western diet had more long-lasting effects on the microbiome than did early-life exercise.

Researchers believe this species of bacteria, and the family of bacteria that it belongs to, might influence the amount of energy available to its host. Research continues into other functions that this type of bacteria may have.

Garland’s team would like to repeat this experiment and take samples at additional points in time, to better understand when the changes in mouse microbiomes first appear, and whether they extend into even later phases of life.

Regardless of when the effects first appear, however, the researchers say it’s significant that they were observed so long after changing the diet, and then changing it back.

The takeaway, Garland said, is essentially, “You are not only what you eat, but what you ate as a child!”

Conclusion/ These results constitute one of the first reports of juvenile diet having long-lasting effects on the adult microbiome after a substantial washout period. Moreover, the researchers found interactive effects of diet with early-life exercise exposure, and a dependence of these effects on genetic background.


Source: Monica P. McNamara, Jennifer M. Singleton, Marcell D. Cadney, Paul M. Ruegger, James Borneman, Theodore Garland. Early-life effects of juvenile Western diet and exercise on adult gut microbiome composition in mice. The Journal of Experimental Biology, 2021; jeb.239699 DOI: 10.1242/jeb.239699