The effect of milk fermented by yogurt cultures plus Lactobacillus casei DN-114001 on the immune response of subjects under academic examination stress.
BACKGROUND
A suppressed immune response has been documented in students under examination stress.


OBJECTIVE
The current study aimed to evaluate the effect of milk fermented with yogurt cultures plus Lactobacillus casei DN-114001 (Actimel) on the immune system of subjects under academic examination stress.


METHODS
University students were allocated to one of two groups, receiving during 6 weeks (3 weeks prior to, as well as the 3-week duration of the examination period) either: a) a glass of semi-skimmed milk each day (control group, n=63) or b) two 100mL portions per day of fermented milk (treatment group, n=73). Anxiety and immunological measurements were monitored at baseline (Phase 0) and study end (Phase 1).


RESULTS
The results were expressed as the differences between the data obtained from Phase 0 and Phase 1. This was calculated by subtracting Phase 1 results from the Phase 0 and it is denominated "Treatment effect". Mean (+/- SE) anxiety increased significantly (P<0.05) over the 6-week study in all students, from 40.74+/-2.50 to 61.19+/-2.64 (in percentiles). There was no significant treatment effect since this increase was similar in the control and the treatment groups (21.65+/-5.09 vs 19.14+/-3.67, respectively). However, there was a significant treatment effect (P<0.05) on the mean change in absolute number of lymphocytes during the 6-week study, which decreased in the control group (-0.04+/-0.12 cells x 10(3)/mm(3)) and increased in the treatment group (0.37+/-0.11 cells x 10(3)/mm(3)). There was also a significant treatment effect (P<0.05) on the change in absolute numbers of CD56 cells during the 6-week study. Mean absolute CD56 cells significantly decreased (P<0.05) in the control group (-51.97+/-21.33 cells/mm(3)),while remaining similar in the treatment group (17.29+/-17.27 cells/mm(3)). During the study, mean serum cortisol increased 4.30+/-0.98 microg/dL in the control group, and 1.75+/-1.05 microg/dL in the treatment group and no significant differences were found between both values (P=0.062).


CONCLUSIONS
Milk fermented with yogurt cultures plus Lactobacillus casei DN-114001 was able to modulate the number of lymphocytes and CD56 cells in subjects under academic examination stress.
Grupo Inmunonutrición, Depo. de Metabolismo y Nutrición, Instituto del Frío, CSIC, C/Jose Antonio Novais 10, 28040 Madrid, Spain. amarcos@if.csic.es
Ascensión
A
Marcos
Julia
J
Wärnberg
Esther
E
Nova
Sonia
S
Gómez
Alberto
A
Alvarez
Rocío
R
Alvarez
José A
JA
Mateos
José M
JM
Cobo
D000293:Adolescent; D000328:Adult; D000818:Animals; D001007:Anxiety / Q000097:blood / Q000276:immunology*; D019002:CD56 Antigen / Q000276:immunology*; D043302:Cultured Milk Products / Q000276:immunology / Q000382:microbiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007109:Immunity / Q000502:physiology; D007780:Lacticaseibacillus casei / Q000378:metabolism*; D018655:Lymphocyte Count; D008297:Male; D008892:Milk
D019002:CD56 Antigen; D006854:Hydrocortisone