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Early-Life Diet and Exercise Impact Later-Life Microbiome

Excess fat and sugar in your diet during childhood can change your microbiome later in life, even if your eating habits become healthier, a new study measuring nutrition in mice suggests.

The research study, conducted by the University of California (UC), is one of the first nutritional reports to explore the juvenile diet and its lasting effect on the microbiome following a significant washout period, which is the equivalent in mice of approximately six human years.

Carried out by lead researcher, biologist Theodore Garland of the UC Riverside (UCR) research team, the study shows a high-fat, high-sugar diet had a long-term impact on the microbiome of mice, raising questions as to whether the same findings may be true for humans.

Malnutrition can refer to the effects of undernutrition as well as overnutrition. Undernutrition stems from an insufficient intake of nutrients due to not having enough to eat. Overnutrition refers to the excessive intake of nutrients, which can lead to adverse health effects usually arising from an accumulation of body fat. Garland and his team focused their study on overnutrition.

Understanding Long-Lasting Effects of Diet and Exercise

Explaining what spurred the UCR researchers to explore the long-term impact of childhood diet, Garland said, “Children are dependent on their parents and other aspects of their environment for the availability of food, but within those constraints, they and their parents make choices as to what foods to eat.”

These food choices that children and parents make and their eating habits can have immediate health impacts. “But the possibility of long-lasting effects, over the course of years, have been less studied,” Garland added, “As have the possible long-term effects of early-life exercise such as riding your bike versus sedentary behavior like playing video games.”

The study, entitled, “Early-Life Effects of the Juvenile Western Diet and Exercise on Adult Gut Microbiome Composition in Mice,” was inspired by the transition in actions and habits that take place from childhood to adulthood. Commenting on what inspired the study, Garland shared that the impetus related to: “Our lab's general interest in what determines adult patterns of exercise behavior.”

“We have been studying the genetic side of things in mice for decades, and more recently turned to studying possible early-life environmental effects,” added Garland.

The study sprang from an interest in what determines adult patterns of exercise behavior.   ©Ty Swartz/Pixabay
The study sprang from an interest in what determines adult patterns of exercise behavior. ©Ty Swartz/Pixabay

The Role of the Microbiome

The microbiome refers to all bacteria, along with fungi, protozoa, and viruses that live both on and inside animals or humans. The majority of these microorganisms that reside in the gastrointestinal tract (GIT) are found in our intestines. On the whole, the microorganisms constituting our microbiome are beneficial, as they help us digest food, regulate our immune system, develop vitamins, and protect against other bacteria that cause disease.

A healthy person or animal with a healthy microbiome will have both the beneficial microorganisms and those that cause disease, known as pathogenic microorganisms. If healthy gut bacteria are detrimentally impacted by factors such as changes in diet or antibiotic use, the resulting shift in microorganisms may result in the host becoming more prone to illness.

Measuring Microbiome Impact of Diet and Exercise

A paper published in the Journal of Experimental Biology on the study saw the research team explore implications on the microbiome by splitting the mice into four groups:

  1. One group of mice was fed the standard ‘healthy’ diet, with no access to a running wheel for exercise;

  2. Another group was fed the less healthy ‘Western’ diet, with no access to the running wheel;

  3. Some of the mice had a standard ‘healthy’ diet, with access to the running wheel; and

  4. The final group was given the ‘Western’ diet, with access to the running wheel.

The mice remained in these four groups and continued to have their diet and exercise monitored for three weeks. After this time, the animals returned to their typical laboratory conditions, where they received a standard diet and no exercise. After 14 weeks, the researchers assessed the diversity, composition, and amount of bacteria in the mice.

How Did Diet and Exercise Affect the Microbiome?

Key findings reveal that the abundance of bacteria such as Muribaculum intestinale—a type of bacteria used in carbohydrate metabolism—was considerably lower in the mice that received the Western diet.

Examining their results, the team identified a decrease in the total number and diversity of gut bacteria in the mature mice that were fed unhealthy diets as juveniles.

“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,” noted Garland in a recent UCR news article.

After analysis, the researchers also found that gut bacteria were sensitive to the amount of exercise the mice received. The abundance of Muribaculum bacteria grew in the group of mice fed a standard diet and who had access to a running wheel. Simultaneously, it reduced in mice on a high-fat diet regardless of whether they exercised.

Based on the study’s findings, the researchers believe that the specific bacteria species, Muribaculum bacteria, and its wider family might affect the amount of energy belonging to the host.

Overall, the UCR research team found that an early-life Western diet in the mice had more long-lasting effects on the animal’s microbiome than exercise in early life did.

The researchers say it is notable that the effects were still visible for such a long period after changing their eating habits and after returning to their standard diet.

As parents, we should think carefully about what we feed our children.”   ©Camarynn Miller, U.S. Navy/Wikimedia
As parents, we should think carefully about what we feed our children.” ©Camarynn Miller, U.S. Navy/Wikimedia

Key Research Takeaways

As Garland opined that the average person does not consider the lifelong ramifications of what they feed their children, the study asserts a clear message regarding the possible implications of its findings for human health: “As parents, we should think carefully about what we feed our kids and how we encourage them to be physically active.”

Emphasizing that information and guidance are also a crucial part of supporting parents with their children’s nutrition, Garland continued, “We should educate them as to the possible long-term consequences of their choices.”

Commenting on how the study’s findings might inform campaigns to end our global nutrition crisis, Garland warned, “What you eat (or cannot eat) as a child may haunt you or help you for years to come.”

Further Research is Underway

Focusing on the next steps following the nutritional study, the researchers are continuing to expand their exploration of the early-life effects of diet and exercise. In a companion paper, Garland noted how the research team reports effects on adult behavior, physiology, and anatomy.

To further understand the longer-term implications of our diets and exercise in childhood and how they affect us into adulthood, the researchers are also conducting a similar study with early-life fructose in the diet.


*Natasha Spencer-Jolliffe is a freelance journalist and editor. Over the past 10 years, Natasha has reported for a host of publications, exploring the wider world and industries from environmental, scientific, business, legal and sociological perspectives. She has also written for market intelligence companies like Innova Market Insights and WGSN. Natasha has also been interviewed herself as an insights provider for research institutes and conferences.


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