NutriPlant - Opportunities for Increasing Consumption of Local Fruits and Vegetables

1. Inclusion criteria: * Signed informed consent of the participant to participate in the study * Age between 18 and 70 years * Functional constipation or irritable bowel syndrome * Expressed willingness to eat the investigated food daily (sauerkraut, apples, dried apples or psyllium; period of four weeks) 2. Exclusion criteria: * Known allergy to the investigated foods (fresh apples, dried apples, sauerkraut or psyllium) * Pregnancy or breastfeeding * Previous gastrointestinal surgery with the exception of cholecystectomy and appendectomy * Other gastrointestinal diseases (chronic inflammatory bowel disease, celiac disease, gastroparesis, etc.) * Serious chronic diseases * Introduction of extensive changes in diet or physical activity in the last 4 weeks before the inclusion examination * Regular use of laxatives or inability to stop using laxatives for the duration of the study * Concurrent participation in another study