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

2. 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

3. 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

4. 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?

5. 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

6. 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)

7. 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)

8. 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

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

10. 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.

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

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

13. 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.

15. 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

16. 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”

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

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

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

20. Thank You!