The purpose of the study is to assess the effect of dietary intervention that includes the daily consumption of a novel biscuit (enriched with the selected mushrooms rich in β-glucans) on gut health related parameters of healthy subjects over 60 years old.

After having been informed about the study and the potential risks, all subjects giving written informed consent will undergo screening to determine eligibility for study entry (inclusion criteria). At baseline, the participants will provide biological samples and they will be randomly assigned in a double-blind manner (investigator and participant) to one of the intervention groups, i.e. consumption of the novel biscuit (biscuit enriched with mushroom powder containing 3g of β-glucans) or consumption of the placebo biscuit for 3 months,. After a washout period of 2 months, the subjects will consume the novel biscuit or the placebo biscuit in a cross-over design for 3 more months. Throughout the interventional period subjects' dietary intake, anthropometrical data and gastrointestinal symptoms will be monitored. Meanwhile at baseline and at the end of each trimester physical activity, mental health and sleep habits will be evaluated with the use of questionnaires and biological samples will be provided for further analysis.

Inclusion Criteria:

• healthy individuals aged 60-80 years old, of both sexes/genders

Exclusion Criteria:

• no recent weight loss and extreme dietary behaviors;
• no history of gastrointestinal disease, chronic constipation, chronic/acute diarrhea, autoimmune disease, coronary disease, liver and/or kidney malfunction;
• no consumption of antibiotics two months prior to the initiation of the intervention;
• no consumption of probiotics and/or prebiotics and/or dietary fiber supplements two weeks prior to the initiation of the intervention.