Lipid Challenge in Adults

Participants in this study will have one visit to the Emory University Hospital Clinical Research Unit. Participants will consume, over 5 minutes, a single standardized fat challenge (100 grams), using a commercially available liquid high-energy long chain triglyceride fat emulsion (Calogen), which provides 50 grams of long chain triglycerides per 100 mL. Participants will have 20 mL blood withdrawn at six successive time points over an 8-hour period, where the first time point after fasting (baseline) is followed by 5 time-points after fat consumption. Blood will be analyzed for a wide panel of blood lipids.

Cardiovascular disease (CVD) is the leading killer of Americans, accounting 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. CCB of the CDC has developed a comprehensive analytical method to measure levels of protein and lipid constituents of lipoprotein size/density classes (e.g. high-density lipoprotein (HDL), low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) in blood. CCB plans to eventually apply this method in future investigations of cohorts with different CVD states. The measurement of this wide array of CVD-linked biomarkers has the potential to improve the assessment of CVD risk over current clinical methods based on lipoprotein classes.

However, limited information is available about how the advanced tests developed by CCB are affected by blood collection conditions, such as fasting/non-fasting state of the subjects. The purpose of this study is to determine the relative significance of these pre-analytical variables and determine optimal conditions for future cohort studies.

This study will recruit up to 32 healthy individuals, with and without obesity, to participate. The study involves one visit to the Emory University Hospital Clinical Research Unit where participants will consume, over 5 minutes, a single standardized fat challenge (100 grams), using a commercially available liquid high-energy long chain triglyceride fat emulsion (Calogen; http://www.nutricia.ie/calogen#), which provides 50 grams of long chain triglycerides per 100 mL. Participants will have 20 mL blood withdrawn at six successive time points over an 8-hour period, where the first time point after fasting is followed by 5 time-points after fat (Calogen) consumption. Blood will be analyzed at the CCB for a wide panel of blood lipids and potential biomarkers for CVD.

Specific expected outcomes of the study include the following: 1) Determination of typical intra-individual differences between fasting and post-prandial states; and 2) Changes in the levels of the various analytes after fat consumption will be indicative of inter-individual differences in the rate of triglyceride depletion, and the rate of accumulation/depletion of HDL or LDL of different particle size range and composition. The results will allow the assessment of significant differences in lipid metabolism between individuals with a normal BMI (20 to 25 kg/m\^2) versus those with a BMI in the obese range (30-35 kg/m\^2).

Eligibility Criteria:
Inclusion Criteria:

* functionally ambulatory
* BMI between \>20 to 40 kg/m\^2
* available for an 8 hour visit to the Emory University Hospital Clinical Research Center

Exclusion Criteria:

* has taken any diabetic or lipid lowering prescription medications within the past 12 months
* history of chronic diseases
* hospitalized within the last year
* currently pregnant
* current active malignant neoplasm or history of malignancy (other than localized basal cell cancer of the skin) during the previous 5 years
* current chronic autoimmune or pro-inflammatory disease
* history of tuberculosis, HIV, or other chronic infection
* previous diagnosis of type 1 or type 2 diabetes with active treatment with insulin or other glucose lowering medication
* advanced (\>= stage 3) renal disease
* recreational or prescription drug or alcohol abuse
* any history of gastrointestinal diseases, including malabsorption
* any history of intolerance to dietary fat
* inability to provide informed consent