The Research Dietitians Role in a Weighed Diet Jamie Garry, MS, RD, LDN, CBDT MGH Clinical Research Center

Nutrient biomarkers may be diagnostic/ therapeutic Clinical Association Diagnosis/ prognosis Nutrient Biomarker New nutritional therapy Proof concept Interventional Study Outcomes trial Effect on other biomarkers In vivo Effects Change in nutrient level Effect on phenotype New pharmacologic therapy New Biology/Mechanism Walford - Nutrition

Clinical Association: Published human studies have demonstrated that tryptophan is a competitive substrate for the organic cation transporter responsible for metformin elimination. Questions: Does dietary tryptophan effect serum tryptophan Does serum tryptophan play a role in metformin response

Clinical Association: Serum BCAA levels are correlated with insulin resistance Questions: Does dietary intake of BCAA effect serum levels of circulating BCAA? Is there a correlation between serum BCAA and insulin resistance?

Nutrients effects of Serum Levels Vitamin D – dietary intake directly effects blood levels Cholesterol – dietary cholesterol not as directly related to serum cholesterol as once believed Calcium - serum levels tightly regulated by body except in cases of disease

Tryptophan Essential amino acids Found in: meat, poultry, eggs, fish dairy, nuts, seeds, beans, grains, and bananas Converts in body to: Serotonin Niacin Tryptophan depletion occurs rapidly (~under 48 hours) Acute Tryptophan Depletion (ATD)

Branch Chain Amino Acids Valine, Leucine and Isoleucine Essential Amino Acids Believed to improve athletic performance and muscle recovery Mixed research Cannot be broken down by patient’s with Maple Syrup Urine Disease (MSUD)

Nutrient biomarkers may be diagnostic/ therapeutic Clinical Association Diagnosis/ prognosis Nutrient Biomarker New nutritional therapy Proof concept Interventional Study Outcomes trial Effect on other biomarkers In vivo Effects Change in nutrient level Effect on phenotype New pharmacologic therapy New Biology/Mechanism Walford - Nutrition

Interventional Studies Proof of concept Pilot studies on healthy individuals Studies on patients with disease states Phase 1 - 4 clinical trials Establish dosage Monitor for side effects Monitor effects of various populations

What is a Weighed diet? Strictly controlled to diet developed to manipulate certain nutrients Examples: Low sodium, TLC diet, renal diet Weighed diets can be one meal, or it can go on for many months. The degree of weighing can also be variable. In some case every food is made from scratch and each ingredient is weighed to the gram or milligram. In other cases, the diets are much less strict such as using “pc” items Help to breakdown confounding factors. Weighed diets can be beneficial in understanding the ‘in vivo’ effects of diet in the short term. Some nutrients themselves have a direct correlation to serum levels of the nutrient and can be used as a useful biomarker. In other cases, dietary intake does not effect serum levels.

Creating a Weighed Diet Considerations: Length of time Cost Study population Allergies/ intolerances Food safety Food procurement Metabolic Kitchen Amenities Staffing

Steps to Developing a Diet Planning diet ProNutra, NDSR Procure Foods Testing Recipes Screen patients Pack Out Weight Back

Screening of Subjects No alcohol, chewing gum, or breath mints Assess typical intake Dietary restrictions Activity Expected compliance Access to storage No alcohol, chewing gum, or breath mints Maintain usual level of physical activity; don’t increase or decrease your usual exercise Consume 100% of the food and beverages given to you No other food or beverages are allowed aside from the following exceptions: Unlimited water (bottled, filtered or tap are fine), please DO NOT consume “enhanced waers” such as Smart Water or Vitamin Water.

Calculating Needs Estimating Current Consumption Equations Food Records 24 hour or 48 hour recalls Equations Mifflin St-Joer Harris Benedict Calories/Kg Activity Factors Resting Energy Expenditure Actual Weight versus Adjusted Weight

Amino Acids Found in foods containing protein Difficult to isolate in whole foods Supplements Pharmacy versus nutrition? If in pill form  pharmacy If in food form  nutrition If in powdered form mixed in food or beverage  Grey Area “Study drug”

Supplements MSUD Express – Low BCAA Solvil – High BCAA Tryptophan Supplements

Practical Implications Increased understanding of metabolic pathways Aid in medication development Dietary recommendations Evidence based practice

Next Steps Pilot study Disease specific Dosing/ Time New pharmalogical therapies

Thank You!