Which type of fiber is associated with increasing favorable bacteria and decreasing serum cholesterol levels?

Soluble fiber is known for its beneficial effects on gut health, particularly in promoting the growth of favorable bacteria and managing cholesterol levels. This type of fiber dissolves in water to form a gel-like substance in the digestive tract, which can bind to bile acids. The binding of bile acids helps lower serum cholesterol levels since the body uses cholesterol to synthesize new bile acids, thereby reducing overall cholesterol levels in the bloodstream.

Moreover, soluble fiber serves as a fermentable substrate for gut bacteria. As these bacteria ferment the soluble fiber, they produce short-chain fatty acids (SCFAs) which contribute to an improved gut environment and have been shown to have various health benefits, including anti-inflammatory effects and positive impacts on glucose metabolism.

In contrast, other types of fiber, such as insoluble fiber, primarily aid in promoting bowel regularity and do not have the same effects on cholesterol or gut flora. Resistant starch offers benefits like improved insulin sensitivity but is not as directly associated with cholesterol reduction as soluble fiber is. Nonfermentable fiber typically does not support bacterial growth in the gut, as it remains unchanged throughout digestion. Therefore, soluble fiber stands out for its ability to increase beneficial bacteria while effectively decreasing serum cholesterol.