How do nonpathogenic bacteria contribute to human health?

Nonpathogenic bacteria play a crucial role in human health, particularly through their contribution to digestion. These beneficial bacteria, commonly found in the human gut, assist in breaking down complex carbohydrates and fibers that the body cannot digest on its own. By fermenting these substances, nonpathogenic bacteria produce short-chain fatty acids, which provide energy to gut cells and support overall digestive health.

In addition to aiding digestion, nonpathogenic bacteria help maintain a balanced microbiome in the intestines, which is essential for robust immune function and nutrient absorption. This balance can prevent the overgrowth of harmful bacteria, thereby reducing the risk of digestive disorders and infections.

The other options are less relevant to the positive impact of nonpathogenic bacteria. While they might serve important functions in other contexts, they do not focus on the specific ways these bacteria contribute to human health. For instance, not all bacteria that decompose organic matter are beneficial to humans, and the presence of bacteria only in water does not accurately represent their diverse roles in environments such as the human body.