Crude fiber (CF)

Crude fiber is an analytical term representing the indigestible portion of plant material, primarily cellulose and lignin, that remains after sequential chemical extraction with dilute acid and alkali (AOAC International, 2023). It is not a specific therapeutic target, such as a receptor or enzyme, but rather a heterogeneous mixture of structural plant components used historically in nutritional labeling (StatPearls, 2023). Biologically, crude fiber and the broader category of dietary fiber function by increasing fecal bulk and promoting regular bowel movements, which is essential for preventing constipation and reducing the risk of diverticular disease (Mayo Clinic, 2022). Additionally, fiber components serve as substrates for colonic bacteria, leading to the production of short-chain fatty acids that support gut barrier integrity and systemic metabolic health (NIH, 2023). While not a drug target itself, high fiber intake can interfere with the pharmacokinetics of various medications, such as digoxin and metformin, by slowing gastric emptying or physically sequestering drug molecules in the intestinal lumen (PubMed, 2021). Consequently, it is a critical dietary factor in the management of chronic conditions like type 2 diabetes and cardiovascular disease (American Heart Association, 2023).

Other names

Dietary fiberRoughagePlant cell wall residueIndigestible residueNon-starch polysaccharides

Physical bulking of stool through water retention, acceleration of colonic transit, and microbial fermentation into short-chain fatty acids (SCFAs) such as butyrate.