SAFETY AND TOLERANCE OF LACTOBACILLUS-REUTERI IN HEALTHY ADULT MALE-SUBJECTS

Thirty healthy, male subjects (age 18 to 75 yrs) were used in a two-gr oup, double-blinded, parallel design to evaluate the safety and tolera nce of a potential probiotic organism, Lactobacillus reuteri. Subjects (15/treatment) consumed two gelatin capsules daily for 21 d that cont ained either a freeze dried L. reuteii preparation in a cryoprotectant , or a placebo (cryoprotectant). The concentration of L. reuteri was s uch that subjects consumed 1 x 10(11) CFU per day. The study was 28 d in length with daily documentation of the presence of gastrointestinal symptoms (nausea, diarrhoea, cramping, distention, flatulence, vomiti ng, constipation, burping and reflux). In addition, serum chemistries, haematology, urinalysis, urinary indican excretion, and faecal microb iota (L. reuteri and total Lactobacillus spp. enumeration) were measur ed weekly (day 0, 7, 14, 21 and 28). A physical exam was given on day 0, 21, and 28. An additional faecal sample was obtained on day 77 for microbial enumeration. Subjects could consume their regular diets; how ever, alcohol was not allowed. Physical exam and urinalysis parameters were not clinically different between treatments. Supplemental L. reu teri reduced (P<0.05) urinary indican excretion at day 7, but had no e ffect (P>0.05) on subsequent urine collections. Although significant d ifferences were observed for a few of the serum chemistry and haematol ogy variables, all of the values remained within the expected normal r ange for healthy adult males. Subjects consuming supplemental L. reute ii had increased (P<0.01) levels of L. reuteri in their faeces on day 7, 14, 21, and 28. However, colonisation was lost within 2 mths of ter mination of L. reuteri consumption (day 77). Levels of total Lactobaci llus spp, never differed (P>0.05) between treatments; however, the rat io of L. reuteri : total Lactobacillus spp. increased (P>0.05) for sub jects consuming supplemental L. reuteri. Incidence of subjective toler ance factors was infrequent and similar for both treatments. In conclu sion, supplemental L. reuteri may be fed at 1 x 10(11) CPU/day without any clinically significant safety or tolerance problems. Intake of L, reuteri (1 x 10(11) CFU/day) results in colonisation (as measured by faecal level) within 7 d of consumption and is maintained for at least 7 d post consumption; however, colonisation is lost within 2 mths of washout.