Background: Diet is one of the most modifiable behaviors affecting health. But diet assessment measures that are based on self-report can be inaccurate. Researchers want better ways to address the role of diet in chronic disease. They want to see if stable isotopes can be used to better assess what people eat. Objective: To see if stable isotopes can help scientists identify things people eat. Eligibility: Healthy adults ages 18 to 65 Design: Participants will be screened with a medical history and physical exam. They will have blood and urine tests. These tests will be repeated during the study. Participants will stay in the inpatient unit of the NIH in Phoenix, Arizona, for 13 weeks. For 7 days, participants will eat a diet prepared by the NIH kitchen. They will get balanced meals that are 50% carbohydrates, 20% protein, and 30% fat. Then participants will be randomly placed on one of 3 diets containing different percentages of carbohydrates from soda. Participants height and weight will be measured. The amount of fat and muscle in their body will be measured by body scans that are similar to x-rays. Participants will have oral glucose tolerance tests. They will consume a sugar drink and then give blood samples over 3 hours. Participants will give hair and stool samples. Participants will complete a diet questionnaire. It assesses their food intake over 24 hours. Participants will complete behavioral questionnaires and computer performance tests. Participants will have fat biopsies taken from their stomach and thigh. Participants will have three 24-hour stays in a metabolic chamber. It is used to measure metabolism.
Study Description: This study will be an inpatient study in which highly specific diets will be fed to volunteers for approximately 12 weeks and stable isotopes will be measured in blood, hair, and adipose. Ultimately, the goal is to develop biomarkers to be used to validate food intake patterns in outpatient clinical and epidemiological studies. Objectives: The primary objective of this study is to validate the use of stable isotope biomarkers as representatives of specific dietary intake patterns. Secondary objectives include evaluation of the effect of the amount of soda on urinary sucrose and fructose excretion, extracellular vesicles levels and content, and gut microbiota. Endpoints (Outcomes): Primary Endpoints: Primary Endpoints: Changes in the blood, hair, and adipose carbon (13C/12C) and nitrogen (15N/14N) stable isotope ratio from baseline to 12 weeks. Secondary Endpoints: Changes in urinary sucrose and fructose excretion, extracellular vesicles levels and content, gut microbiota from baseline to 12 weeks.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
60
Weight-maintaining diet without soda, with all carbohydrates originating from sources other than corn and sugar cane
Weight-maintaining diet with 50% of carbohydrates provided as soda, and all other carbohydrates originating from sources other than corn and sugar cane
Weight-maintaining diet with 20% of carbohydrates provided as soda, and all other carbohydrates originating from sources other than corn and sugar cane
NIDDK, Phoenix
Phoenix, Arizona, United States
RECRUITINGChange in the blood carbon stable isotope ratio (13C/12C) from baseline to 12 weeks.
We will test biomarker diet relationships at the week 8, 10 and 12 sampling time points, using linear mixed effects models to evaluate single CIR biomarkers of SSB in plasma. Specifically, we will also test the time x group interaction by including it as a fixed effect in the mixed model analysis to evaluate the differences in the rate of CIR change over time across groups. Baseline CIR will be included as covariate in the mixed model analysis.
Time frame: Baseline, Week 8, Week 10, Week 12
Change in the hair carbon stable isotope ratio (13C/12C) from baseline to 12 weeks.
We will test biomarker diet relationships at baseline and 12 weeks to determine differences in values over time and dose.
Time frame: Baseline, Week 12
Change in the carbon stable isotope ratio of alanine from baseline to 12 weeks.
We will examine the time response of CIR-alanine. We will use a difference of 1.5 (Infinite) (+/-) from baseline as a preliminary criterion and adjust to ensure balanced representation of treatments in the 'time response' subset of participants. From these participants we will measure CIR-alanine at all timepoints. We will assess temporal change in CIR- alanine by examining week-to-week correlations to identify the time point at which biomarker measurements become independent of baseline, and by using linear mixed models to model the longitudinal trends over time.
Time frame: Baseline, every two weeks through Week 12
Change in urinary sucrose/fructose over time and with varying levels of SSB intake.
Repeated measures two-way ANOVA will be employed to assess the between-subjects effect and to compare the daily sugars excretion during different levels of sugars intake.
Time frame: Baseline, every two weeks through Week 12
24h EE and its components from the metabolic chamber.
Diet-induced changes in EE will be assessed for significance using a paired t test (before/after intervention) and ANCOVA (dose).
Time frame: Baseline, Week 1, Week 12
To determine the effect of dietary changes on the microbiome of the gut, single stool samples will be collected upon admission and completion.
We will measure 16s rRNA on stool samples before and after dietary intervention.
Time frame: Baseline, Week 12
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