GLOSSARY

Mucus Layer is a mucin-rich coating regulating contact, distinct from the whole mucosal tissue.

The intestinal barrier permits selective exchange while mucus, cell junctions and immunity limit inappropriate passage. Complete closure is not its physiological goal. Some claudins form selective pathways, and junction proteins have different roles. Increased expression of one protein in an experiment does not prove complete human barrier function. Functional measures and personal context remain necessary alongside molecular names when judging a proposed nutrition intervention.

The mucosa actively interfaces with food and microbes, combining selective uptake with defense. The intestinal barrier includes cells, junctions, mucus and immune functions rather than one sealed wall. Research permeability changes do not diagnose disease from fatigue or bloating alone. Persistent athlete symptoms warrant assessment; a promise to repair the gut immediately does not replace identifying the cause and maintaining adequate nutrition.

Villi are multicellular mucosal projections; microvilli are tiny extensions of individual absorptive cells. Microvilli form the brush border containing enzymes and transporters. Crypts are invaginations with renewing and specialized cells. These organizational levels differ. Greater surface supports absorption, but the appearance or name of a structure does not calculate the absorbed percentage of a person's meal or prove a supplement increases it.