Diet influences type and mix of gut bacteria more than genes.

gutAnother study, from the University of California, has demonstrated that diet has a stronger influence in regulating genes than determining the mix of bacteria in a gut. Numerous studies have demonstrated how crucial gut bacteria are in regulating the immune system and their impact on a number of adverse health conditions.

The study published in the journal Host & Microbe, used mice models to investigate whether the variation in genes is due mostly to genes (nature), or environmental influence such as diet and lifestyle and revealed that the level of bacteria and type can easily be modified.

Mice were fed two different diets, altering between a high-fat, high-sugar diet (14.8% protein, 44.6% fat and 40.6% carbohydrate) and a low-fat, plant-based diet (22.2% protein, 16.0% fat and 61.7% carbohydrate). Switching the mice to a high-sugar, high-fat diet altered the mix of microbes in their gut to a new, stable mix within 3 days. The effect could be replicated and was mostly independent of the genetic variations among the mice. Regardless of the mice’s genetic makeup, the high-fat, high-sugar diet increased the abundance of Firmicutes bacteria and reduced the abundance of Bacteroidetes bacteria.

“These new results emphasize that, unlike a mammalian genome – which is relatively constant – the microbial genomes that comprise the gut microbiome are relatively plastic,” Peter Turnbaugh, an assistant professor of microbiology and immunology at the University of California San Francisco (UCSF) said.

The researchers suggest that one day it may be possible to treat diseases by shaping the balance of bacteria in the gut. The microbial response to a given diet may be similar for many people’s microbial communities.

When mice were returned to their original diets, changes in the gut microbe mix were largely reversible. However, the imprint of past diets played a role in determining gut microbe mix.

“Repeated dietary shifts demonstrated that most changes to the gut microbiota are reversible. But we also identified bacterial species whose abundance depends on prior consumption,” said Prof. Turnbaugh.


Diet Dominates Host Genotype in Shaping the Murine Gut Microbiota, Rachel N. Carmody et al., Cell Host & Microbe, doi:10.1016/j.chom.2014.11.010, published online 18 December 2014, abstract.

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