[Fresh versus pasteurized yogurt: comparative study of the effects on microbiological and immunological parameters, and gastrointestinal comfort].
OBJECTIVE
To determine whether the beneficial effects of yogurt are dependent on the viability of lactic bacteria and exclusive to fresh yogurt, by comparison with the effects of yogurt that is pasteurized after fermentation.


METHODS
Using a double-blind design in a healthy adult population over 75 days, we compared the effects of fresh and pasteurized yogurt on microbiological (presence of viable bacteria in yogurt and DNA detection in feces) and immunological (nephelometry, hematometry, and flow cytometry) parameters. A questionnaire was used to assess gastrointestinal comfort. Differences in lactose absorption after ingestion of fresh or pasteurized yogurt were determined by breath hydrogen analysis.


RESULTS
There were no significant differences in the results obtained for microbiological or immunological parameters, gastrointestinal comfort, or lactose test between the two types of yogurt ingested. Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) was isolated in 0.7% of the fecal samples analyzed. Streptococcus thermophilus was not found in any sample. DNA from lactic bacteria was detected in only 12.5% of the samples analyzed.


CONCLUSIONS
Transit through the gastrointestinal tract affects survival of L. bulgaricus and S. thermophilus. No differences were found in the immunological parameters, gastrointestinal comfort, or lactose overload after intake of fresh or pasteurized yogurt.
Ballesta
Sofía
S
Departamento de Microbiología de la Facultad de Medicina. Universidad de Sevilla, Avenida de Sánchez Pizjuán s/n, Seville, Spain. mudarra@us.es
Velasco
Carmen
C
Borobio
Ma Victoria
MV
Argüelles
Federico
F
Perea
Evelio J
EJ
D001944:Breath Tests; D004269:DNA, Bacterial / Q000032:analysis; D004311:Double-Blind Method; D004415:Dyspepsia / Q000209:etiology; D005243:Feces / Q000382:microbiology; D005414:Flatulence / Q000209:etiology; D005511:Food Handling; D041981:Gastrointestinal Tract / Q000382:microbiology; D006358:Hot Temperature; D006801:Humans; D007136:Immunoglobulins / Q000097:blood; D007408:Intestinal Absorption; D007778:Lactobacillus / Q000302:isolation & purification / Q000502:physiology; D007785:Lactose / Q000009:adverse effects / Q000493:pharmacokinetics; D007787:Lactose Intolerance / Q000453:epidemiology / Q000209:etiology; D007958:Leukocyte Count; D048249:Streptococcus thermophilus / Q000302:isolation & purification / Q000502:physiology; D011795:Surveys and Questionnaires; D015014:Yogurt / Q000009:adverse effects / Q000382:microbiology*
D004269:DNA, Bacterial; D007136:Immunoglobulins; D007785:Lactose