New York, Feb 3 (IANS): Eating too much fat and sugar as a child can alter your microbiome for life, even if you later learn to eat healthier, a new study suggests.

The microbiome refers to all the bacteria as well as fungi, parasites, and viruses that live on and inside a human or animal.

Most of these micro-organisms are found in the intestines, and most of them are helpful, stimulating the immune system, breaking down food and helping synthesize key vitamins, the researchers said in the mice-based study.

"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," said researcher Theodore Garland from the University of California, Riverside, US.

For the study, published in the Journal of Experimental Biology, the team looked for impact on the microbiome after dividing the 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.

They found that 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.

The analysis also showed 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.

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.

One other effect of note was the increase in a highly similar bacteria species that were enriched after five weeks of treadmill training in a study by other researchers, suggesting that exercise alone may increase its presence.

Overall, the researchers found that early life Western diet had more long-lasting effects on the microbiome than did early life exercise.