Exam stress has previously been shown to suppress immune response in students so scientists at the CSIC in Madrid tested whether the fermented milk drink Actimel, containing Lactobacillus casei bacteria, could shore up the immune systems of students doing exams.
They divided almost 150 university students into two groups to receive either a glass of semi-skimmed milk or two 100 mL portions of Actimel daily for three weeks prior to exams and continuing throughout the three-week examination period.
Anxiety levels increased significantly in all students, they report in a 14 July online edition of the European Journal of Nutrition (DOI: 10.1007/s00394-004-0517-8).
But while the number of lymphocytes - a kind of white blood cell circulating in the blood - decreased significantly in the control group during the study, the levels increased in the Actimel group, they reported.
Lymphocytes are responsible for the production of antibodies. Probiotics have previously been associated with improved immunity. Recent results found mothers taking probiotic supplements to have higher levels of an anti-inflammatory molecule in their breast milk, which could offer their babies better protection against disease.