Consumption of a fermented dairy beverage improves hippocampal-dependent relational memory in a randomized, controlled cross-over trial

ABSTRACT

Objectives: We aimed to determine whether consumption of a fermented dairy beverage containing probiotic microorganisms influences negative mood states, stress, and hippocampal memory performance in healthy adults. Methods: Adults (25-45 yrs, N = 26) free of gastrointestinal and mental illness were enrolled in a single-blind, randomized, controlled, crossover trial. Participants completed testing prior to and after 4-week consumption, with a 2–4 week washout between treatments of: (1) 8 oz of a dairy-based fermented beverage containing 25–30 billion colony forming units of live and active kefir cultures or (2) 8 oz isocaloric, non-fermented, 1% low-fat lactose-free dairy-based control beverage. Hippocampal-dependent relational memory was assessed using a spatial reconstruction task. Negative mood states of depression and anxiety were assessed using the Depression Anxiety Stress Scales-42 (DASS-42). Pooled 24-hour urine samples were analyzed using an enzyme-linked immunosorbent assay to determine urinary free-cortisol (UFC) concentrations. Fecal microbiota composition was assessed using 16S rRNA gene sequencing. Results: Lactobacillus was increased by 235% following fermented dairy consumption compared to the control (p < .01). Furthermore, the fermented dairy beverage improved performance on two metrics of relational memory, misplacement (p = .04) and object-location binding (p = .03). UFC and DASS-42 scores (all p’s > .08) were not significantly changed by either arm of the intervention. No correlations were observed between the change in Lactobacillus and memory performance. Conclusions: Fermented dairy consumption increased the presence of certain microorganisms in the gut and improved relational memory in healthy adults. However, the benefits observed for relational memory were not related to changes in Lactobacillus.

Trial registration: ClinicalTrials.gov identifier: NCT02849275.

KEYWORDS:

• Probiotics
• intestinal microbiota
• cognition
• stress
• depression
• anxiety
• fecal microbiota
• hippocampus

Acknowledgements

C.N.C. wrote the first draft of the manuscript. A.R.M. recruited and scheduled participants. C.N.C., A.R.M., and M.A.B collected and scored the data. N.J.C. assisted in interpretation of memory data and conceived of the task. N.A.K. and H.D.H. conceived of the study and acquired funding. All authors contributed to editing the manuscript.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

USDA National Institute of Food and Agriculture, Hatch Project 1009249

Notes on contributors

Corinne N. Cannavale

Corinne N. Cannavale is a Postdoctoral research assistant in the Department of Kinesiology and Community Health at the University of Illinois Urbana-Champaign. She completed her PhD in Neuroscience at the University of Illinois Urbana-Champaign.

Annemarie R. Mysonhimer

Annemarie R. Mysonhimer is a doctoral candidate in the department of Food Science and Human Nutrition at the University of Illinois Urbana-Champaign.

Melisa A. Bailey

Melisa A. Bailey completed her Master's in Food Science and Human Nutrition at the University of Illinois Urbana-Champaign.

Neal J. Cohen

Neal J. Cohen is a Professor of Psychology and the Director of the Interdisciplinary Health Science Institute at the University of Illinois Urbana-Champaign. He received his PhD in Psychology from the University of California, San Diego.

Hannah D. Holscher

Hannah D. Holscher is an Associate Professor of Nutrition in the Department of Food science and Human Nutrition and Division of Nutritional Sciences at the University of Illinois Urbana-Champaign. She completed her PhD in Nutritional Sciences at the University of Illinois Urbana-Champaign. She is also a Registered Dietitian.

Naiman A. Khan

Naiman A. Khan is an Associate Professor in the Department of Kinesiology and Community Health, Neuroscience Program, and Division of Nutritional Sciences at the University of Illinois Urbana-Champaign. He completed his PhD in Nutritional Science at the University of Illinois Urbana-Champaign. He is also a Registered Dietitian.