Dietary Supplementation with Fermented Milk Containing Probiotics Improves Behaviour and Immune Response of Aged Mice

Aging is associated with an impairment of the regulatory systems, including the nervous and immune systems as well as the communication between them. The consumption of fermented milk containing live probiotic bacteria seems to have neurological and immunological benefits. The aim of the present study was to evaluate the effects of the supplementation with a fermented milk containing yogurt cultures and the probiotic Lactobacillus casei DN-114001 on behaviour and immune functions of old mice as well as on their life span. Also, the in vitro properties of these probiotics on functions of peritoneal leukocytes were analysed. Old female ICR-CD1 mice were supplemented with fermented milk containing probiotics. After 1 and 4 weeks of supplementation, behavioural tests were performed and immunological functions in peritoneal leukocytes studied. The results showed that a short-term (one week) supplementation with fermented milk containing probiotics was able to improve behavioural aspects (such as motor coordination, equilibrium, muscular vigour, exploratory activity and anxiety-related behaviour) as well as immune functions in old mice that had been impaired by age, reaching similar levels to those found in adult controls. Furthermore, a longer-term supplementation (four weeks) was able to maintain these improvements in the immunological parameters. Probiotics seem to have a direct effect on several immune functions. In conclusion, the supplementation with fermented milk containing probiotics could be a good nutritional strategy to improve behaviour and immune system functions in old individuals and, consequently, to promote healthier aging.