The trillions of microorganisms that live in all of our guts can play an integral role in our wider health, and it’s well-established that a healthy diet – as well as exercise – can help to manage this important ecosystem. However, a new study in mice suggests that eating an unhealthy diet as a child may alter your microbiome for life, even if you learn to eat healthier in later life.
In particular, the findings suggest that eating too much fat and sugar as a young'un may permanently decrease the total number and diversity of gut bacteria. Once again, this study was only carried out on mice in the lab, so the findings should be taken with a pinch of salt (no pun intended). Nevertheless, the researchers argue their findings highlight the importance of providing kids with a healthy diet.
“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," Theodore Garland, study author and evolutionary physiologist at the University of California, Riverside, said in a statement.
"You are not only what you eat, but what you ate as a child!"
As reported in the Journal of Experimental Biology, the researchers gathered a collection of juvenile mice and subjected them to two different diets: the standard “healthy” diet, or one rich in salt and sugar (which the researchers call a “Western diet”). Half of each of these groups were given access to a running wheel for exercise, while the other half had no access to exercise. Once they hit sexual maturity at around 6 weeks of age, they were then housed individually and fed on a standard diet.
After 14 weeks, the team then analyzed the diversity and abundance of bacteria in the animals by looking at their poop samples. One of the key findings was that the mice fed the “Western diet” had notably lower levels of Muribaculum intestinale, a bacteria involved in carbohydrate metabolism. This species of bacteria also increased in mice fed a standard diet who had access to a running wheel, and decreased in mice on a high-fat diet regardless of whether they exercised.
In sum, the findings suggest that eating an unhealthy diet at a young age had a more noticeable and long-lasting effect on the gut microbiome than early-life exercise.
The bacteria, fungi, parasites, and viruses that live in the intestines of humans and other animals can have a surprisingly profound effect on the rest of the body, known to play a central role in stimulating the immune system, breaking down food, and obtaining nutrients and vitamins. Scientists are only just starting to understand how our microbiome can impact humans, but it’s becoming increasingly clear that these microorganisms are linked to many diseases. A recent study linked the richness of a person’s gut bacteria to how severely they fall ill with COVID-19, while another found a robust link between neurodegenerative illnesses such as Alzheimer’s disease and compounds released by gut bacteria.