Cognitive and Metabolic Effects of a Probiotic Supplement

Placebo-controlled Randomized Trial of Cognitive and Metabolic Effects of a Probiotic Supplement

To examine the cognitive and metabolic effects of a probiotic supplement that is readily and already available for purchase in public drug stores. This study is a double-blinded randomized cross-over placebo-controlled intervention study. Participants will be randomized to receive either the probiotic supplement or the placebo during the first intervention period which will last 2 weeks. This will be followed by a washout period, after which they will proceed to the second intervention period, also lasting 2 weeks and also followed by a washout period.

Inclusion Criteria:

• Male
• Age 18-28y
• Healthy (self-reported) and not on medication
• Non-smoking
• Normal sleep-wake rhythm (i.e. 7-8 h per night, self-reported via diaries)
• Regular meal patterns with daily breakfast

Exclusion Criteria:

• Major illness
• Taking any serious medications
• Any sleep conditions (e.g. irregular bedtimes, sleep complaints)
• Any dietary issues with the food items provided
• Current or history of endocrine, neurological or psychiatric disorders
• Shift work in the preceding three months or for a long duration
• Time travel over a significant number of time zones in the preceding two months
• Too much weight gain or weight loss in the preceding three months
• Excessive intake of fermented dairy products
• Intake of probiotics
• Recent antibiotic treatment (last 6 months)
• Recent intake of certain dietary supplements
• Excessive caffeine (>5 cups daily) or alcohol intake (>2 alcohol units daily)