Use of Stable Carbon And Nitrogen Isotopes to Improve Dietary Assessment for Cardiovascular Disease

Study Overview
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Brief Summary
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In this research study, the investigators will use a novel approach to measure what people eat. The goal is to find out whether stable isotopes that can be measured in blood, hair, and fingernails are better at measuring what people eat than the surveys that are currently used. To meet the goal, the investigators will do three things. First, the investigators will feed study participants known amounts of foods and nutrients. Second, after study participants have eaten the food, the investigators will measure stable isotopes in samples of study participants' blood, hair, and fingernails. Third, the investigators will determine how well these samples reflect what was eaten. The investigators will also give surveys to study participants to determine how well the surveys reflect what was eaten. This will allow the investigators to do a relative comparison of the measurements from isotopes and surveys.

Detailed Description
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This is a controlled feeding study in which the relative validity of stable carbon and nitrogen isotope ratio analysis as a biomarker of dietary intake is compared to controlled feedings and multiple 24-hour recalls. Participants will be randomly assigned to a sequence of diets to be fed on four occasions. Participants will undergo 24 hours of controlled feeding on four non-consecutive days over a month-long period. On the day after feeding, participants will complete 24-hour dietary recalls, and provide blood, hair, and fingernail samples for isotope ratio analyses. The investigators will use a crossover design and the diets will be either high or low in C4 plants (i.e., corn and cane products). A 24-hour urine collection will be done at home during each 24-hour feeding period. Participants will have height and weight measured at the screening visit. Weight will also be measured at each study visit. Additionally, data will be collected via questionnaires administered at each study visit.

Official Title
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Use of Stable Carbon And Nitrogen Isotopes to Improve Dietary Assessment for Cardiovascular Disease

Conditions
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Healthy Adults

Intervention / Treatment
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* Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level
* Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + one serving sugar sweetened beverage
* Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + two servings sugar sweetened beverage
* Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + three serving sugar sweetened beverage


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: men and women; aged 21 and 74 years; no history of chronic disease and in general good health; able to provide primary study outcome; and willing to tolerate study diets designed for controlled feeding. Exclusion Criteria: recent dietary changes, restrictions, allergies or preferences; health conditions that require management beyond the scope of the study (e.g. heart failure, kidney disease, liver disease, gastrointestinal disorder); history of drug or alcohol abuse; plans to leave the San Diego area before study completion; and lack of suitability per investigators' discretion.

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 74 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Health Services Research
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Dietary intervention consisting of four 24-hour feeding periods (1 feeding period per week for 4 weeks).
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 50g added sugar<br>Crossover design and each participant receives all 4 experimental arms/doses in random order | Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level<br>* 50g added sugar<br>|
| Experimental: 90g added sugar<br>Crossover design and each participant receives all 4 experimental arms/doses in random order | Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + one serving sugar sweetened beverage<br>* 90 grams added sugar<br>|
| Experimental: 130g added sugar<br>Crossover design and each participant receives all 4 experimental arms/doses in random order | Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + two servings sugar sweetened beverage<br>* 130 grams added sugar<br>|
| Experimental: 170g added sugar<br>Crossover design and each participant receives all 4 experimental arms/doses in random order | Dietary Supplement: one 24 hr cycle of meals at a 2000 kcal level + three serving sugar sweetened beverage<br>* 170 grams added sugar<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Carbon isotope values from blood | The ratio of carbon 13 to carbon 12 in human blood will be determined. | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Carbon isotope values from hair | The ratio of carbon 13 to carbon 12 in human hair samples will be determined. | 30 days | 
| Carbon isotope values from fingernails | The ratio of carbon 13 to carbon 12 in human fingernail samples will be determined. | 30 days | 
| Nitrogen isotope values from blood | The ratio of nitrogen-15 to nitrogen 14 in human blood will be determined. | 30 days | 
| Nitrogen isotope values from hair | The ratio of nitrogen-15 to nitrogen 14 in human hair will be determined. | 30 days | 
| Nitrogen isotope values from fingernails | The ratio of nitrogen-15 to nitrogen 14 in human fingernails will be determined. | 30 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Isotopes, Sugar, Diet, Health