Effect of Functional Foods on Gut Microbiota in Metabolic Syndrome

This study was a single-center, randomized, controlled, double-blind, parallel versus placebo that consisted of five visits. The first visit was a screening evaluation to determine whether subjects met the inclusion criteria. The selected subjects were invited to a second visit that consisted of a medical history, 2-h oral glucose tolerance test (OGTT), the collection of stool samples for DNA isolation and collection of 5 ml blood sample. The participants received during the first stage, a low saturated fat diet (LSFD) for 15 days. In the third visit and second stage of dietary treatment, subjects were randomized to receive the dietary portfolio (DP) or placebo (P) treatment + an LSFD accompanied of a reduced energy diet for 1 mo. In the fourth visit, with a 1 mo interval, dietary assessment and compliance to the DP or P were evaluated. During each follow-up visit, a 24-h dietary recall was collected, a physical activity questionnaire was filled out and anthropometric and clinical parameters were assessed. In the fifth visit, a 2 -h oral glucose tolerance test (OGTT) was performed, and a stool sample for DNA isolation and 5 ml blood were collected.

Dietary intervention in the first stage, the participants consumed a reduced-energy diet tailored to provide a 500-kcal/d deficit as recommended by NIH with respect to their habitual diet for 15 days. The diet plan consisted in 50-60% carbohydrates, 15% protein, 25-35% fat, <7% saturated fat, ≤ 200 mg, 20-35 g fiber, 2000 mg/d sodium based on total energy. In the second stage, the participants continued to consume the reduced energy diet with the addition of a combination of functional foods (DP). The DP provided 200 kcal that were subtracted from the diet. The DP consisted of a mixture of 14 g de dehydrated nopal, 4 g of chia, 25 g of soy protein, 14 g of oat, 4 g of inulin, 0.15 of flavoring. The placebo (P) consisted of 30 g of calcium caseinate, 30 g of maltodextrin and 0.2 g of flavoring. The kcal, appearance, and flavor were similar in DP and P. The DP and P were given in a package in the dehydrated form ready to be dissolved in water. The DP was divided into two packages, the first package contained 17.3 g of DP or P given in the breakfast and dissolved in 250 ml and the second package was given at the dinner time, and contained 34.7 g of P and DP dissolved in 300 ml of water.

Dietary compliance. Dietary compliance was assessed with a 24-h dietary recall and 3-d food record (food lo), during each visit that was analyzed by food processor nutrition analysis software. The compliance of the consumption of the DP or P was evaluated with the number of empty packages returned at the following visit. Physical activity was assessed using the International physical activity questionnaire (IPAQ)