USDA Western Human Nutrition Research Center (WHNRC) Cross-Sectional Nutritional Phenotyping Study

Many inflammatory responses can be modulated by specific dietary components. For example, in
cardiovascular disease, macrophages and T-cells react with oxidized LDL (an endogenous
modified antigen) to produce arterial plaque and subsequent blockage of coronary arteries.
High intake of saturated fats (or simple sugars that drive synthesis of saturated fatty
acids) may promote this inflammation by affecting macrophages and T-cells. Conversely,
increased intake of omega-3 fatty acids may decrease inflammation by suppression of
macrophage and T-cell pro-inflammatory activity. Long-term sub-clinical inflammation caused
by intestinal bacteria has been linked to the development of Irritable Bowel Disease and
related disorders. Low intake of fruits, vegetables, or whole grains or high intake of
saturated fats may promote sub-clinical gut inflammation by promoting dysbiosis of the gut
microbiota. Allergic asthma develops in predisposed individuals as a result of an overactive
allergic-type immune response to inhaled environmental allergens. Dietary factors such as
vitamin D and omega-3 fatty acids may diminish pro-inflammatory responses to environmental
allergens by promoting the development of T-regulatory cells and other anti-inflammatory
factors.

Individual variability in chronic disease risk is well recognized. For example, why does
excess adiposity lead to disease in some individuals and not others? The nature of the fat
tissue rather than the abundance, may impact cross-talk with other metabolically-relevant
tissues and affect disease risk. It is important to characterize healthy vs. unhealthy
phenotypes across various tissues and to understand how micro- and macro-nutrients interact
with molecular and metabolic pathways to support a healthy body weight. This study brings
together scientists with expertise in nutritional sciences, immunology, analytical chemistry,
physiology, neuroendocrinology, and behavior to understand how diet impacts metabolism and
disease risk through the interplay and coordination of signals and metabolites arising from
multiple organ systems.

The overall objective is to characterize the phenotypic profile of participants according to
their immunologic, physiologic, neuroendocrine, and metabolic responses to a dietary
challenge and a physical fitness challenge by addressing the specific aims listed below. The
cross-sectional study is organized into two study visits (Visit 1 and Visit 2) separated by
approximately two weeks of at-home specimen and data collection.

Specific Aim 1: To determine if diet quality is independently associated with systemic immune
activation, inflammation, or oxidative stress differentiated by:

1. pro-inflammatory T-helper cells (Th1, Th2, and Th17 cells) and related cytokines

2. anti-inflammatory T-regulatory cells and related cytokines

3. dysbiosis of the gut microbiota and markers of gut inflammation (e.g. neopterin and
myeloperoxidase)

a. and to evaluate the association between dysbiosis of the gut microbiota, gut
inflammation, and systemic immune activation

4. plasma metabolomic response to a mixed macronutrient challenge meal (includes diet
quality and physical activity as independent variables)

5. endothelial (dys)function and vascular reactivity

Specific Aim 2: To determine if a high fat/sugar challenge meal induces differential effects
over time (0-6h postprandial) according to habitual diet characteristics, physical activity
levels, stress levels, age, sex, or BMI on:

1. postprandial monocyte activation

2. plasma lipid metabolomic responses including non-esterified fatty acids, phospholipids,
triacylglycerols, red blood cell fatty acids, endocannabinoids, bile acids, eicosanoids
and related oxylipins, ceramides, sphingoid bases, and acylcarnitines

3. plasma amino acid metabolomics

4. glucose metabolism and metabolic flexibility (i.e. the ability to switch from glucose to
lipid oxidation as energy sources)

5. changes in endocrinology and self-report of hunger and satiety

6. postprandial free cortisol

Specific Aim 3: To determine the mechanisms of:

1. postprandial monocyte activation

2. suppression of challenge-meal induced monocyte activation by docosahexaenoic acid (DHA)
(in an ex vivo experiment using a subset of samples)

Specific Aim 4: To evaluate the associations between eating behavior, physical activity,
and/or anthropometry and the outcomes:

1. endocrinology of hunger and satiety

2. plasma metabolomic responses

3. vulnerability and resistance to stress

4. endothelial (dys)function and vascular reactivity

5. prediction of insulin sensitivity

Specific Aim 5: To determine how genetic variants affect nutrient metabolism, cardiovascular
physiology, and immune function and improve understanding of how dietary factors affect these
metabolic, cardiovascular and immune phenotypes.

Inclusion Criteria:

- 18-65 y

- Male or female

- Body Mass Index 18.5-45.0 kg/m2 (Normal to obese)

Exclusion Criteria:

- Pregnant or lactating women

- Known allergy to egg-white protein

- Systolic blood pressure greater than 140 mm Hg or diastolic blood pressure greater
than 90 mm Hg measured on three separate occasions

- Diagnosed active chronic diseases for which the individual is currently taking daily
medication, including but not limited to:

- Diabetes mellitus

- Cardiovascular disease

- Cancer

- Gastrointestinal disorders

- Kidney disease

- Liver disease

- Bleeding disorders

- Asthma

- Autoimmune disorders

- Hypertension

- Osteoporosis

- Recent minor surgery (within 4 wk) or major surgery (within 16 wk)

- Recent antibiotic therapy (within 4 wk)

- Recent hospitalization (within 4 wk)

- Use of prescription medications at the time of the study that directly affect
endpoints of interest (e.g. hyperlipidemia, glycemic control, steroids, statins,
anti-inflammatory agents, and over-the-counter weight loss aids)