Probiotics are foods that contain live bacteria, which are beneficial to health. Kefir is a stirred beverage made from milk fermented with a complex mixture of bacteria, including various species of lactobacilli, lactococci, leuconostocs and aceterobacteria and yeasts (both lactose-fermenting and non-lactose-fermenting) (Thoreux & Schmucker, 2001). A number of studies suggest stimulation of immune function and suppression of cancer by consumption of probiotics, as well as improved intestinal microbial balance (Collins & Gibson, 1999).

The aim of the present study is to report data about effects of kefir on enzymes and proteins of the gut. Kefir was incubated with pepsin (20 mg (g protein)^-1) after acidification to pH 2.5 with HCl, and this mixture was mixed for 1 or 2 h at 37 °C. The proteolysis was stopped by neutralization of pH by NaOH addition. Nitrogen content was measured by the Kjeldahl method. Jejunal brush-border membrane vesicles (BBMV) were isolated from adult pigs (humanely killed) by the method of Shirazy-Beechey et al. (1990). After protein determination BBMV were incubated with digested kefir for 30 min at 37 °C. Intestinal sucrase and maltase activities were determined in control and with kefir conditions by the methold of Dahlqvist (1964).

The protein quantity of kefir and kefir digested for 1 or 2 h was 2.89, 1.47 and 1.76 %, respectively. Sucrase activity was diminished (P < 0.05, Student’s paired t test) after incubation of digested kefir for 2 h and maltase activity was also reduced (P < 0.05) with the probiotic.

These data indicate that kefir intake appears to modify the intestinal disaccharidase activities due to the bioactive components. Further studies are needed to confirm this conclusion.

This work was supported by the Government of Navarra.