Which of the following are absorbed in the Colon?
Ans. B. Short-chain Fatty Acids. (Ref. Harrion 18th/ Table 294-3 \Ganong 23rd/ pg. 464 & 466; Ch.27)# Short-chain fatty acids (SCFAs) are produced in the colon and absorbed from it.Comparison of Different Types of Fatty Acids Long-ChainMedium-ChainShort-ChainCarbon chain length>128-12<8Present in dietIn large amountsIn small amountsNoOriginIn diet as triglyceridesOnly in small amounts in diet as triglyceridesBacterial degradation in colon of nonabsorbed carbohydrate to fatty acidsPrimary site of absorptionSmall intestineSmall intestineColonRequires pancreatic lipolysisYesNoNoRequires micelle formationYesNoNoPresence in stoolMinimalNoSubstantial SHORT-CHAIN FATTY ACIDS IN THE COLON# Short-chain fatty acids (SCFAs) are produced in the colon and absorbed from it. SCFAs are two- to five-carbon weak acids that have an average normal concentration of about 80 mmol/L in the lumen. About 60% of this total is acetate, 25% propionate, and 15% butyrate. They are formed by the action of colonic bacteria on complex carbohydrates, resistant starches, and other components of the dietary fiber, that is, the material that escapes digestion in the upper GIT and enters the colon.# Absorbed SCFAs are metabolized and make a significant contribution to the total caloric intake. In addition, they exert a trophic effect on the colonic epithelial cells, combat inflammation, and are absorbed in part by exchange for H+, helping to maintain acid-base equilibrium. SCFAs are absorbed by specific transporters present in colonic epithelial cells. SCFAs also promote the absorption of Na+, although the exact mechanism for coupled Na+-SCFA absorption.
Long chain fatty acids
Short chain Fatty Acids
Medium chain FA
None
G.I.T.