REDUCED DIGESTIBILITY OF BEEF TALLOW AND COCOA BUTTER AFFECTS BILE-ACID EXCRETION AND REDUCES HEPATIC ESTERIFIED CHOLESTEROL IN RATS

We investigated stearic add (18:0) digestibility and how it affects bi le acid excretion in male Sprague Dawley rats fed diets containing (g 18:0/100 g fatty acids): pork lard (13); beef tallow (19); cocoa butte r (35); corn oil (2) or corn oil plus cholestyramine for 25 d. Apparen t lipid digestibility was reduced with increased dietary intake of 18: 0 as follows: lard (90%), beef tallow (82%), cocoa butter (78%), chole styramine (87%), and corn oil (94%); P < 0.001, pooled sD = 2. Hepatic : concentrations of total and esterified cholesterol were significantl y less in cocoa butter-, beef tallow- and cholestyramine-fed groups co mpared with lard- and corn oil-fed groups. Fecal bile acid excretion w as significantly greater in rats fed cocoa butter or cholestyramine co mpared with those fed corn oil. The half-life of intraperitoneally adm inistered C-14- cholic acid was significantly longer in rats fed cocoa butter (1.36 +/- 0.02 d) compared with cholestyramine (0.98 +/- 0.03 d) and intermediate in those fed corn oil, lard or beef tallow (1.11-1 .21 +/- 0.05 d). Fecal excretion of muricholic adds (bile acids) corre lated strongly with dietary intake of 18:0 (r(2) = 0.98, P < 0.01), wh ereas excretion of bile acids derived from cholic and chenodeoxycholic acids was similar among groups, In summary, the lower digestibility o f cocoa butter is associated with increased fecal bile acid excretion, reduced hepatic concentration of esterified cholesterol, decreased fr actional turnover of C-14-cholic acid and increased excretion of muric holic acids In rats, The mechanism by which stearate-rich dietary fats alter bile acid and cholesterol metabolism is, however, uncertain.