for people ages 25-75 (full criteria)
Healthy Volunteers
healthy people welcome
at UC Davis
study started
completion around



Flavanols are compounds present in plants, including apples, berries, peaches, cocoa-derived products and certain beverages like tea. Following intake, they are absorbed and broken down into smaller compounds called 'metabolites'. Some of these metabolites are excreted in urine. In this study, we hope to collect urine and examine the metabolites to learn more about the types and amounts of flavanols that people are consuming as part of their usual diet.

Official Title

Flavanol Intake in Davis (FID) Study: Biomarker-estimated Habitual (-)-Epicatechin and Flavanol Intake in Adults


Flavanols, including the monomers (-)-epicatechin and (+)-catechin, and their related oligomeric derivatives, the procyanidins, are a group of plant-derived, dietary bioactives amply present in the diet. Supported by accumulating epidemiological studies and outcomes from the first large-scale randomized study with bioactives, the COcoa Supplement and Multivitamin Outcomes Study (COSMOS), the Academy of Nutrition and Dietetics released the first dietary recommendation for flavan-3-ols intake in the United States (US). This recommendation suggests the consumption of 400-600 mg/d of flavan-3-ols to mediate cardiometabolic beneficial effects, including the reduction of cardiovascular disease risk. While previous studies have aimed at assessing dietary intake of this group of bioactives, the tools used for these assessments were based on dietary questionnaires and food content databases. These tools are subjective and known to present significant limitations. Recently, our laboratory developed a series of nutritional biomarkers to objectively assess flavanol intake and thus, overcome limitations inherent to previous methods. These biomarkers are based on the quantification of a series of flavanol metabolites, including the 5-(3,4-dihydrophenyl)-γ-valerolactone metabolites (gVLM) and the structurally related (-)-epicatechin metabolites (SREMs). These biomarkers provide complementary information; as while gVLM provide information about the intake of flavanols in general, SREMs are specific biomarkers of (-)-epicatechin intake. In addition, gVLM are surrogate biomarkers, which means that this biomarker allows ranking volunteers from low to high flavanol consumers without providing information on absolute intake. On the other hand, SREMs proved to perform as a recovery biomarker when assessed in 24-hour urine, thus providing absolute amount of (-)-epicatechin consumed. While gVLM and SREM biomarkers have been used to assess the intake of flavanols and epicatechin in the United Kingdom, little is known about biomarker-estimated intake of flavanols in the US, and even less when considering the use of SREM as a recovery biomarker. Therefore, the characterization of flavanol and epicatechin intake in a US population will provide essential information to understand efforts to promote flavanol intake based on current dietary recommendations and thus increase access of the health benefit related to the consumption of these bioactives to the public in general.


Adults, Flavanols, Dietary flavanols, Phytonutrients, Bioactives, Observational, (-)-epicatechin


You can join if…

Open to people ages 25-75

  • 25 - 75 years old
  • Male or female
  • BMI 18.5 - 34.9 kg/m2
  • Weight ≥ 110 pounds
  • Computer, tablet or smart phone with cellular data/Wi-Fi to establish video call communication

You CAN'T join if...

  • Adults unable to consent
  • Prisoners
  • Non-English speaking*
  • BMI ≥ 35 kg/m2
  • Indications of substance or alcohol abuse within the last 3 years
  • Cancer of the GI tract, previous GI surgery (except appendectomy) or GI stoma
  • History of difficult blood draws
  • Diarrhea, defined as 3 or more loose or liquid stools/day, within the last 3 months or antibiotic intake within the last 3 months
  • Currently participating in a clinical or dietary intervention study
    • Non-English speaking volunteers will be excluded for safety reasons, as we do not have staff that can adequately provide interpretation services that can explain and answer questions with regard to study procedures.


  • University of California Davis accepting new patients
    Davis California 95618 United States


accepting new patients
Start Date
Completion Date
University of California, Davis
Study Type
Expecting 200 study participants
Last Updated