The Mixed Meal Challenge Study
Condition: Cardiovascular Diseases; Hyperlipidemias
MeSH terms: Cardiovascular Diseases; Hyperlipidemias; Hyperlipoproteinemias
Study type: Interventional

Summary: 
      The purpose of this study is to assess sample collection conditions for various dietary
      challenges (fat, sugar, and mixed) and determine the optimal fasting and post-meal sample
      collection time points for future studies on a larger group of individuals. Study
      participants will attend three study visits where they take part in lipid, glucose, and mixed
      meal challenges. At each of the three visits, participants will provide venous blood samples
      and a urine sample before consuming the test meal and will provide 6 additional venous finger
      blood samples post-meal.
    

Detailed description: 
      Cardiovascular disease (CVD) is the leading killer of Americans, accounting for more than
      800,000 deaths each year. A vital step in reducing the number of heart disease-related deaths
      in the U.S. is to identify those at probable risk. The Clinical Chemistry Branch (CCB) in the
      Division of Laboratory Sciences (DLS) at the Centers for Disease Control and Prevention (CDC)
      has developed advanced analytical methods for assessing the risk for lipid metabolism related
      diseases, including CVD. This comprehensive analytical method measures levels of protein and
      lipid constituents of lipoprotein size and density classes (e.g. high-density lipoprotein
      (HDL), low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL)) in blood. The
      analytical method uses asymmetric flow-field flow fractionation (AF4) to separate lipoprotein
      classes (HDL, LDL, VLDL) in serum or plasma into size fractions, and in each fraction
      quantifies over 50 CVD-linked biomarkers by isotope dilution tandem mass spectrometry. The
      CCB plans to apply the measurement of this wide array of biomarkers in future epidemiologic
      investigations of CVD. These studies have the potential to expand the number of
      diagnostically relevant CVD risk factors that currently are limited to cholesterol and
      triglyceride measurements.

      However, there is limited information about how the CVD-linked biomarkers measured with the
      CCB's method are affected by blood collection conditions and the fasting/non-fasting state of
      individuals. Furthermore, lipid metabolism is very dynamic and the absolute levels of
      biomarkers are strongly affected by each individual's diet, lifestyle, gender, age, and
      physiology. Thus, assessing biomarkers related to lipid metabolism is most effective in a
      pre- and post-test comparison (i.e. fasting vs. after a test meal) with controlled lipid and
      carbohydrate content.

      The study involves three different meal challenges on three separate days with approximately
      two weeks in between. The first meal challenge will involve the consumption of a standardized
      mixture of dietary fats (lipid challenge), the second meal challenge will be a sugar
      sweetened beverage (glucose challenge) and the third meal challenge will be a nutrition shake
      (mixed meal challenge). At each of the three visits, each individual will provide both venous
      and finger-prick blood samples and a urine sample before consuming the test meal (in a
      fasting state) and 6 additional venous and finger-prick blood samples post-meal at described
      intervals. Each study visit will last approximately 8 hours.
    

Intervention name(s): Lipid Challenge; Glucose Challenge; Mixed Meal Challenge
Intervention type(s): Dietary Supplement; Dietary Supplement; Dietary Supplement
Intervention description(s): For the lipid challenge, participants consume 100 grams of a long chain triglyceride emulsion in the form of liquid drink, which is the commercially available brand called Calogen, from Nutricia, Inc.; For the glucose challenge, participants consume 75 grams of glucose in 200 milliliters of water, which is the World Health Organization (WHO) recommended drink for the Oral Glucose Tolerance Test.; For the mixed-meal challenge, participants consume 237 milliliters of the Ensure Enlive nutrition drink , which contains 11 grams of fat, 22 grams of sugar and 20 grams of protein.
Other intervention name(s): Calogen; Ensure Enlive
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Prevention; Hyperlipidemia; Cardiovascular disease