2.2. Study Design
BLOOD
The first phase consisted of a cross-sectional study performed to compare gut permeability in 24 young well-trained male elite football athletes and 23 sex-matched amateur athletes as controls by measuring the levels of LPS, zonulin, and occludin, three biomarkers that can accurately detect alterations in intestinal barrier integrity [Blood levels of LPS, zonulin, and occludin were assessed at baseline (T0) and 30 days (T30d) after the last ingestion of chocolate. During the study, the participants followed a diet adjusted according to their anthropometric and clinical characteristics and to the number of calories coming from chocolate intake while also avoiding foods with a high polyphenol content and/or additional chocolate.