What is the primary cause of a diverse and balanced human microbiome that contributes positively to overall health?

A diverse and balanced human microbiome mainly comes from the wide variety of microbes we meet early in life through food, pets, nature, and everyday activities. When we eat different foods, touch soil or plants, and share spaces with people and animals, our gut and skin pick up many harmless bacteria that help digest food and fight off bad germs. This constant exposure trains our immune system to stay calm and protects us from infections. For example, a child who plays outside and eats fruits, grains, and fermented foods will develop a richer mix of bacteria than someone who stays indoors and eats only processed foods. The more microbes we encounter, the healthier our bodies stay.