2.3 Measures
2.3.1 Gut microbiome. The gut microbiome was assessed using fecal specimens. According to the Human Microbiome Project (HMP) protocol27, parents and children were taught to collect fecal specimens using the stool collection kit and store them in freezer at home before shipping to the laboratory. During the hospital visit, the trained research staff provided the parent with the fecal sample collection kit. The samples were frozen before being shipped to the Biobehavioral Laboratory at School of Nursing, Emory University. Once received by the research staff, the stool samples were stored in a -80℃ freezer until DNA extraction and assaying.
2.3.2 Dietary intakes. The dietary intake of nutrients was measured using the Block Kids Food Screener (BKFS), which includes 41 items developed by NutritionQuest (Berkeley, CA, US). This instrument has been validated to evaluate dietary intake of nutrients and food groups among children aged 2-18 years. Parents, together with their child, completed the BKFS to estimate the child’s intake of fruit, vegetables, dairy, whole grains, protein sources, saturated fat, and sources of added sugars. The frequency of food and beverage consumption ranges from “none” to “every day”. Studies have proved that BKFS has good relative validity to examine the nutrients and food groups in children and adolescents. Overall correlations with 24-hour dietary recalls and with the Food Frequency Questionnaires (FFQ) were high and Bland-Altman plots showed strong agreements between BKFS and FFQ28. In this study, macronutrients and antioxidant nutrients were analyzed 29,30.
2.3.3 Demographic and clinical variables. Child’s demographic data (e.g., age, gender, race/ethnicity, height, weight, and BMI percentile), health history (e.g., use of antibiotics and disease history), cancer diagnosis and treatment data (e.g., diagnosis and cycles of chemotherapy) were obtained from the electronic medical record.