Fiber-enriched Croissant Consumption and Effects on Metabolic Status, Appetite and Gut Microbiota

Associations between human health, diet and gut microbiota composition and functionality have been widely highlighted by the scientific literature in this field. Evidence shows that population adopting a Western dietary model, with a reduced intake of dietary fiber, undergo an adaptation of the gut microbiota characterized by the loss of some bacterial species and a general reduction in microbial biodiversity. The national guidelines for a healthy diet suggest to include daily fruit, vegetables, whole grains and legumes (the main sources of fiber in the diet) in the habitual diet to reduce the risk of diseases and to improve health. However, the compliance with these nutritional recommendations is generally low among individuals. Therefore, the commercial availability of dietary fiber-enriched products could be advantageous.

Breakfast is an important meal that should provide at least 20% of the daily calories with an adequate supply of all nutrients. Having fiber-enriched foods for breakfast could bring numerous nutritional benefits and if they are made with sourdough may be even better. Indeed, sourdough leavened baked products provide compounds with potential prebiotic activity, reduce the glucose and insulin response, increase satiety and reduce gastro-intestinal disorders upon consumption.

The hypothesis is that the combination of sourdough and dietary fiber in baked products could further ameliorate glucose metabolism in consumers compared to sourdough products.

The aim of this study is to evaluate the effects of a daily consumption at breakfast for 2 weeks of a sourdough croissant enriched with dietary fibers from 10 different sources vs a sourdough croissant with no fiber added (control) on daily energy intakes, metabolic and inflammatory status, appetite feelings, body weight, body mass index (BMI), waist and hip circumferences, body composition, blood pressure, gut microbiota composition and gastrointestinal functionality in healthy subjects.

Inclusion criteria

• healthy subjects;
• men and women;
• age 18-50 years;
• 20 kg/m2 ≤ BMI ≤ 35 kg/m2;
• habitual daily breakfast consumption (≥ 250kcal/day);
• habitual diet characterized by absence of any food supplements and alternative medication, probiotics and prebiotics, whole grain and/or fiber enriched foods;
• intake of fruit/vegetables < 3 servings/day;
• low level of physical activity;
• signed written informed consent.

Exclusion criteria

• food allergies and intolerances and celiac disease;
• gastrointestinal diseases;
• relevant diseases;
• pregnant or breastfeeding;
• previous abdominal surgery;
• hypertriglyceridemia (Triglycerides > 200 mg/dL);
• hypercholesterolemia (Total cholesterol > 200 mg/dL);
• hyperglycaemia (glycaemia ≥ 110 mg/dL);
• hypertension (arterial blood pressure ≥140/90 mm Hg);
• weight loss ≥ 3 kg within 2 months before the study;
• antibiotics treatment within 3 months before the study;
• any medication (different from antibiotics) at the enrollment and within 2 months before the study;
• habitual diet characterized by high fruit and vegetables intakes (>3 portion/die);
• high level of physical activity;
• alcohol consumption ≥ 3 alcohol units per day;
• simultaneous participation in other trial.