Cognitive and mood effects of a dietary supplement containing probiotics, vitamins and zinc: a randomized, double-blind, placebo-controlled crossover study in healthy humans.

Anxiety and depression are highly influenced by stress. These three conditions
are often intertwined and can impact the normal cognitive functioning.
Developing a novel therapeutic methods for treatment of these mood disorders,
as well as exacerbation from outside stressors, is necessary to moderate their
impact on the quality life and boost cognitive performance. A novel class of
probiotic microorganisms, called psychobiotics, is emerging as able to convey
benefit upon the host*s mental health via the bidirectional dynamic
microbiota-gut-brain crosstalk. Growing evidence in animal models is confirming
that treatments targeting the gut microbiota with specific probiotic strains
appear an appealing strategy to ameliorate anxiety symptoms. Furthermore,
vitamins like B6 and D, and mineral like zinc have claimed effects to
contribute to the normal functioning of the nervous system. Several studies
have demonstrated the synergistic impact of combined vitamins or mineral and
probiotic administration to affect hormonal, inflammatory and oxidative stress
parameters, but no study on humans have investigate this synergic effect on
mood and cognitive functions. Therefore, this study aim to evaluate the
efficacy of a novel treatment composed of probiotics plus vitamin B6, D and
zinc on relieving stress and boost cognitive performance in healthy humans, by
modulating the microbiota-gut-brain axis.

To evaluate a probiotic formula, including selected strains able to produce
neurotransmitters, vitamin D, B6, and zinc to provide new, safe and effective
therapeutic option for:

- Boosting cognitive performance
- Prevent the onset of memory impairment age and stress related
- Manage psychological reaction to stress
- Alleviate anxiety symptoms

A 12 week randomized, double-blind, crossover, placebo-controlled trial.
Subjects will be evaluated at a screening visit for eligibility in the study
based on inclusion and exclusion criteria. The participants will be randomized
in two arms and they will receive the product or placebo for 4-weeks and then
they will switch to the alternative treatment for 4 weeks after a wash-out
period of 4 weeks. Following the enrollment of participants, repeated measures
of DASS-42, LEIDS-R, CogState task and stool will be collected at baseline and
at the end of each intervention, until the end of the trial to evaluate the
effects of the probiotic formula compared to placebo on the psychobiological
responses to stress and assess cognitive performance.

The participants are assigned randomly to 2 equal-size groups on the first
testing day. During the intervention period, one-half of the total sample
receive once daily the active product as a stick, whereas the other half
receive once daily the placebo stick for four weeks. The study includes a
4-week washout period in which subjects receive no treatment for the indication
under study and the effects of a previous treatment are eliminated. After 4
weeks of washout, the treatment order is reversed with a length of four weeks.
Cognitive performance (CogState battery), mood questionnaires (LEIDS-r and
DASS-42), biological samples (stool) are collected and assessed in each
session, pre-and post-intervention periods.

There are several burdens subjects can experience during the study. Subjects
will be recruited at the Division of Human Nutrition, Helix Building,
Wageningen University Department four times (test sessions). The volunteers are
invited to complete online or by phone call for being selected based on the
inclusion and exclusion criteria. After the enrollment, subjects have to ingest
1 stick of the probiotic supplementation or placebo daily. Each participant
will undergo four test sessions, one at baseline and others after each
intervention of 4-week duration, including the washout period. Each test
session will take approximately 60 minutes, and includes the mood
questionnaires LEIDS-r and DASS-42, and cognitive function test through
CogState Battery. In the first session it will be asked to fill also the Food
Frequency Questionnaire. Furthermore, the participants have to follow their
habitual diet but avoid the intake of food enriched in probiotics as fermented
food (kefir, kombucha) or other dietary supplement containing probiotics and
vitamins, and avoid excessive intake of coffee and alcoholics drink for all the
12 weeks.

The subjects can benefit from the dietary supplements as composed of probiotic
strains that have *generally accepted as safe* status. Indeed the term
probiotic includes all the live microorganisms able to confer a health benefit
on the host when administered in adequate amounts as defined by the Food and
Agriculture Organization of the United Nations and WHO (FAO/WHO, 2002).
The vitamin B6, contained inside the dietary supplementation contributes to the
normal functioning of the nervous system, to normal psychological function, and
to the reduction of tiredness and fatigue. Vitamin D3 contributes to the normal
absorption and utilization of calcium and phosphorus and to the normal
functioning of the immune system. The zinc contributes to normal cognitive
function and to the protection of cells from oxidative stress
This study will lead to knowledge about the effect of probiotic strains on
cognitive functioning in healthy stressed human, which can lead to general
benefits for the public in the future
The subjects will receive a final compensation of ¤ 98 for their participation
if they complete the whole study.