Fruit and Vegetable Biomarker Discovery

The purpose of this research is to find a set of markers in the blood and/or urine that can be linked to consumption of specific fruits and vegetables. This will allow for better understanding of the link between diet and health-related outcomes. Furthermore, the results of this study will lead to the development of new methods to evaluate the nutritional status of individuals in both community and clinical settings. Food frequency questionnaires and diaries/recalls can be affected by intentional or unintentional misreporting, and thus can create errors in determining nutritional status. This study will lead to the development of an objective way to assess the consumption of specific fruits and vegetables by the general population.

This study includes 3 aims to identify and then validate urine and plasma biomarkers associated with fruit and vegetable intake. Aim 1 will use a randomized crossover dietary intervention to determine the dose and time response of metabolites in plasma and urine associated with exposure to a mixture of MyPlate fruits and vegetables. Aim 2 will use a parallel design, controlled diet intervention to determine whether the biomarkers of fruit and vegetable intake determined in Aim 1 are predictors of consumption in the context of a defined dietary pattern. Aim 3 will be a cross-sectional validation arm that determines if the biomarkers of food intake developed in Aims 1 and 2 have predictive value reflecting recent and habitual consumption of these foods in a heterogeneous and diverse population.

Inclusion criteria

• Body Mass Index (BMI) 18.5-39.9 kg/m^2
• Willingness to provide urine and have blood drawn

Exclusion criteria

• Pregnancy or lactation
• Allergy or aversion to foods provided in test diet
• History of gastrointestinal disorders including the following:

• Ulcerative colitis or Crohn's disease
• Celiac sprue
• Hereditary non-polyposis colorectal cancer (HNPCC)
• Familial adenomatous polyposis
• Pancreatic disease
• Liver disease
• Previous gastrointestinal resection or bariatric surgery
• Bleeding disorders that preclude blood draws
• Recent hospital admissions (past 6 months) for myocardial infarction (MI), cerebrovascular accident (CVA), or congestive heart failure (CHF)
• Cardiovascular disease (CVD) under physician guided therapy that is not medically stable
• Cancer under radiation or chemotherapy treatment that is active or within 6 months of treatment
• Weight change (± 5% in the last 3 months)
• Regular alcohol intake of > 2 drinks/day (equivalent to 720 mL of beer, 240 mL of wine, or 90 mL of spirits), and unwilling to abstain during feeding periods
• Use of tobacco and/or marijuana, hookahs, e-cigarettes, or vapes and not willing to abstain during feeding periods
• Use of illicit drugs and not willing to abstain during feeding periods
• BMI >40 kg/m^2
• Regular (daily to weekly) use of over-the-counter (OTC) weight-loss aids and unwilling or unable to stop taking these during feeding periods
• Regular (daily to weekly) use of OTC anti-inflammatories and unwilling or unable to stop taking these during feeding periods
• Unwilling to stop taking OTC dietary supplements that interfere with the test foods being studied including pills, chewables, liquids or powders for the following (may continue if vitamin supplement is prescribed by a medical doctor):

• Protein supplements
• Soy
• Fiber
• Flaxseed
• Fish oil (including cod liver oil)
• Probiotics
• Carotenoids
• Selenium
• Other antioxidants
• Other phytochemicals
• Glucosamine
• Chondroitin
• Oral or IV antibiotic use in the past 6 months (could defer participation until 6 months post-completion of course of antibiotics)
• Seated blood pressure >140/90 mmHg
• Fasting clinical lab values outside of the following ranges:

• Fasting Glucose: 54-125 mg/dL
• Urea: 6-50 mg/dL
• Creatinine: 0.4-1.3 mg/dL
• Estimated Glomerular Filtration Rate (eGFR): >60 mL/min
• Sodium: 133-146 mmol/L
• Alanine Transaminase (ALT): 5-60 U/L
• Aspartate Aminotransferase (AST): 5-40 U/L
• Alkaline Phosphatase (ALP): 20-135 U/L
• Total Bilirubin: 0.0-1.9 mg/dL
• Total Protein: 5-9.0 g/dL
• Albumin: 3.5-5.9 d/L
• Low-density Lipoprotein (LDL) Cholesterol: <160 mg/dL
• Triglycerides: <500
• White Blood Cells: 3-10.5 Kl/µL
• Hematocrit: 35-48 g/dL (women), 37.5-49 g/dL (men)
• Current use of the following prescription medications:

• Diuretics
• Steroids (oral): daily oral any dose within 1 month of study (except for oral contraceptive pills)
• Opiates: any use within 1 month of study
• Hypolipidemic agents that affect GI or renal function (ie. fibrates)
• Hypoglycemic medications other than metformin (ie. insulin, SGLT2 inhibitor, α-glucosidase inhibitor)
• Psychiatric medications that affect metabolism/renal function (anti-psychotics, lithium)
• Biologics/immune modulators (ie. rheumatoid arthritis, psoriasis, other rheumatologic/hematologic active disease)
• Anti-coagulants (coumadin, heparin, Eliquis, etc.)
• HIV/HAART medications (dyslipidemia inducing)
• Inability to freely give informed consent