Prebiotics may alter bile salt hydrolase activity: Possible implications for cholesterol metabolism

Probiotics secrete bile salt hydrolase (BSH) which catalyses the deconjugation and excretion of bile salts in the GI tract altering cholesterol metabolism in the liver. Many probiotic preparations include prebiotics to promote probiotic growth but little is understood about how prebiotics affect BSH activity. In this study the ability of probiotic Lactobacilli species to deconjugate bile salts in the presence of various prebiotics was determined by measuring cholic acid release. The kinetic properties of BSH was assessed to determine the impact the prebiotics on bile salt deconjugation. When L. acidophilus NCTC 1723 was incubated with inulin (1%) there was a significant (p < 0.01) increase in cholic acid release by 0.16 nmol/min. Lactulose and lactobionic acid at 1% decreased cholic acid release to 0.2 nmol/min and 0.06 nmol/min respectively. In the presence of the pure BSH, inulin and lactulose (0-6%) altered Kₘ and Vₘₐₓ of the enzyme with a Kᵢ of 12% and 10.5% respectively. By contrast, lactobionic acid (2%) increased BSH activity two-fold (p < 0.01).

These results confirm that prebiotics are capable of altering BSH activity in vitro. Similar changes in vivo could potentially affect the claimed health benefits of synbiotics particularly where the desired outcome is lowering of serum cholesterol.