Effect of diester and diether phosphatidylcholine on intestinal absorption of neutral and acidic sterols.

The effects of nondigestible diether phosphatidylcholine on intestinal absorption of cholesterol and dihydroxy and trihydroxy conjugated bile salts were studied in bile fistula rats using radioactive substrates. No inhibition of absorption of either dihydroxy or trihydroxy bile salts was observed. Nondigestible phospholipid did, however, significantly inhibit cholesterol absorption. Under control conditions with natural phosphatidylcholine in the intestinal perfusate, absorption of cholesterol was significantly greater when infused with taurocholate (TC) as compared to results obtained after infusion with taurochenodeoxycholate (TCD). Studies were repeated using radioactive rat liver phosphatidylcholine to determine whether the observed decrease in cholesterol absorption could be correlated with a decrease in digestion and absorption of rat liver phosphatidylcholine. No evidence was found for decreased absorption of this phospholipid when given with TCD. It is concluded that less cholesterol is absorbed in the presence of TCD as compared to TC, but the mechanism for this remains unexplained.