Walnut Ingestion in Adults at Risk for Diabetes: Effects on Body Composition, Diet Quality, and Cardiac Risk Measures
Condition: Diabetes
MeSH terms: Diabetes Mellitus
Study type: Interventional

Summary: 
      Proposed is a randomized, controlled, modified Latin square parallel design study with two
      treatment arms to examine walnut consumption effects on diet quality, body composition, and
      markers of cardiovascular risk in adults at risk for diabetes over a 6-month period. A
      modified crossover design (Latin square)27-29 will allow for both paired and unpaired
      analyses.
    

Detailed description: 
      Specific Aims

        -  To determine the effects of a walnut-included diet (with or without caloric intake
           adjustment) versus walnut-excluded diet on diet quality in adults at risk for diabetes.
           Specifically, to show that a walnut-included diet, as compared to a walnut-excluded diet
           will improve overall diet quality as measured by the Alternative Healthy Eating Index in
           adults at risk for diabetes.

        -  To determine the effects of a walnut-included diet (with or without caloric intake
           adjustment) versus walnut-excluded diet on body composition in adults at risk for
           diabetes. Specifically, to show that a walnut-included diet, as compared to a
           walnut-excluded diet for 6 months will improve body fat percentage in adults at risk for
           diabetes.

        -  To assess the effects of a walnut-included diet (with or without caloric intake
           adjustment) for a 6-month period on endothelial function, lipid panel levels, fasting
           glucose level, fasting insulin level and anthropometric measures in adults at risk for
           diabetes. Specifically, to show clinically meaningful improvement in endothelial
           function, lipid panel, fasting blood glucose, hemoglobin A1c (HbA1c), anthropometric
           measures and endothelial function with inclusion of walnuts in the diet in adults at
           risk for diabetes.

      Hypotheses

        -  A walnut-included diet with or without dietary counseling to adjust caloric intake will
           improve diet quality in adults at risk for diabetes.

        -  A walnut-included diet for 6 months with or without dietary counseling to adjust caloric
           intake will improve body composition in adults at risk for diabetes.

        -  A walnut-included diet with or without dietary counseling to adjust caloric intake will
           improve lipid panel, fasting blood glucose, hemoglobin A1c, endothelial function and
           anthropometric measures in adults at risk for diabetes.

        -  Controlling calorie intake to keep it constant with the addition of walnuts to the diet
           will enhance the beneficial effects of walnut ingestion on diet quality, body
           composition, and vascular function.
    

Intervention name(s): Walnut Ad libitum diet; Walnut Calorie controlled
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Participants will be provided 392 grams of walnuts per week (56g or 2 oz/day) to include in their diet. Their calorie intake will not be subsequently monitored or regulated, and thus will be allowed to float ad libitum; The intervention group participants will meet with a registered dietitian and receive instructions and recipes for inclusion of 392 grams of walnuts per week (56g or 2 oz/day) in their meal plan for 6 months.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Investigator)
Primary purpose: Prevention
Keywords: Obesity; Walnuts; Endothelial Function; Adults at risk