Define Absorption, Storage and Elimination of Riboflavin?

Riboflavin is absorbed from the small intestine through the portal vein and is passed to all tissues via general circulation. Absorption occurs in the upper part of the gastrointestinal tract by specialized transport involving a phosphorylalation dephosphorylalion mechanism more than by diffusion. This process is sodium- dependent and involves an ATP ase active transport system. Delaying intestinal transit time may result in an increase in the total amount of riboflavin absorbed from the intestine.

Intestinal uptake is increased in cellular riboflavin deficiency and decreased with a high riboflavin status. Riboflavin is also synthesized by intestinal bacteria and then absorbed by the colon. This riboflavin produced by bacterial synthesis also contributes to overall riboflavin nutrition. Transport of' riboflavin involves loose binding to albumin and tight binding to a number of globulins -several classes of immunoglobulins (IgA, IgG and IgM). Riboflavin is not stored in the body. A major part is excreted in urine and the rest is broken down in the tissues.