Abstract
Elderly adults have alterations in their gut microbiota and immune functions that are associated with higher susceptibility to infections and metabolic disorders. Probiotics and prebiotics, and their synbiotic combinations are food supplements that have been shown to improve both gut and immune function. The objective of this randomised, double-blind, placebo-controlled, cross-over human clinical trial was to study immune function and the gut microbiota in healthy elderly adults. Volunteers (n 37) consumed prebiotic galacto-oligosaccharides (GOS; 8g/d), probiotic Bifidobacterium lactis Bi-07 (Bi-07; 10(9) colony-forming units/d), their combination (Bi-07+GOS) and maltodextrin control (8g/d) in four 3-week periods separated by 4-week wash-out periods. Immune function was analysed by determining the phagocytic and oxidative burst activity of monocytes and granulocytes, whole-blood response to lipopolysaccharide, plasma chemokine concentrations and salivary IgA levels. Gut microbiota composition and faecal SCFA content were determined using 16S ribosomal RNA fluorescence in situ hybridisation and HPLC, respectively. Primary statistical analyses indicated the presence of carry-over effects and thus measurements from only the first supplementation period were considered valid. Subsequent statistical analysis showed that consumption of Bi-07 improved the phagocytic activity of monocytes (P<0·001) and granulocytes (P=0·02). Other parameters were unchanged. We have for the first time shown that the probiotic Bi-07 may provide health benefits to elderly individuals by improving the phagocytic activity of monocytes and granulocytes. The present results also suggest that in the elderly, the effects of some probiotics and prebiotics may last longer than in adults.
Highlights
Adults have alterations in their gut microbiota and immune functions that are associated with higher susceptibility to infections and metabolic disorders
The number and diversity of beneficial bifidobacteria have been shown to decline in some studies, indicating that a detrimental shift in the balance of microbial species occurs with ageing[1,4]
A randomised placebo-controlled cross-over clinical trial was designed to study the effect of probiotic Bifidobacterium animalis subsp. lactis Bi-07 (Bi-07), prebiotic GOS or their synbiotic combination Bi-07 + GOS on gut and immune functions in healthy non-institutionalised elderly adults
Summary
Adults have alterations in their gut microbiota and immune functions that are associated with higher susceptibility to infections and metabolic disorders. Changes to the physiology and function of the gastrointestinal tract and immune system status occur[1] These changes are associated with increased susceptibility to infections, metabolic disorders and frailty that have significant impact on the quality of life in elderly individuals and healthcare costs to society. Despite the increased levels of pro-inflammatory cytokines, it seems that the reactivity of the innate and adaptive immune systems in the elderly is poorer In vivo these findings are perhaps best highlighted by low vaccination responses that lead to higher susceptibility to infections[10,11]. An appealing approach to modulate gut microbiota, poor immune response and detrimental effects of the ageing population is through the use of dietary interventions that have an impact on both the gut microbiota and immune function
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