Cardiometabolic Effects of Pecan Snacking in Prediabetes

Glycemic Effects of Substituting Pecans for Snacks Higher in Saturated Fat and Added Sugars in Individuals With Prediabetes

The purpose of this study is to investigate the effects of replacing snacks higher in saturated fats and added sugars with pecans on blood sugar control, heart health and diet quality in individuals with prediabetes. Participants will be randomized into one of two groups. Group 1 will consume 1.5 oz of pecans per day in place of normally consumed snacks higher in saturated fat and added sugars for 16 weeks. Group 2 will be asked to continue consuming their current diet for 16 weeks. Measures will be taken to evaluate blood sugar, heart health and dietary intake at the beginning and 16 weeks later.

This is a 16-week randomized controlled trial. Participants will be randomized to either: 1) replace current snacks higher in saturated fat and added sugars with 1.5 oz/day of pecans; 2) continue their habitual diet. At the beginning and the end of the 16-week study period, testing will be conducted.

Inclusion Criteria:

• Age 25-65 years
• Prediabetes assessed by an HbA1c of 5.7-6.4% at screening
• BMI 25-40 kg/m2 at screening
• Low habitual nut consumption (<3.5 oz-eq/week) assessed at the telephone screening
• Regularly eats snacks higher in saturated fat and/or added sugars assessed at the telephone screening

Exclusion Criteria:

• LDL-C ≥190 mg/dL at screening
• Hemoglobin <13.2 g/dL at screening
• Fasting triglycerides >350 mg/dL at screening
• ≥10% change in body weight within the 6 months prior to enrollment
• Blood pressure >140/90 mmHg at screening
• Type 1 or type 2 diabetes
• Prescription of anti-hypertensive, lipid-lowering, or glucose-lowering drugs
• Intake of supplements or over-the-counter medications that affect the outcomes of interest (i.e., lipid, blood pressure, or glucose lowering; vitamin C or multi-vitamins containing vitamin C) and are unwilling to cease during the study period.
• History of liver, kidney, or autoimmune disease
• Prior cardiovascular event (e.g., stroke, heart attack)
• Current pregnancy or intention of pregnancy within the next 12 months
• Lactation within the prior 6 months
• Pecan allergy/intolerance/sensitivity/dislike
• Unwilling/unable to eat 1.5 oz of pecans every day as a snack during the duration of the study
• Antibiotic use within the prior 4 weeks
• Oral steroid use within the prior 4 weeks
• Use of tobacco or nicotine-containing products within the past 6 months
• History of cancer at any site within the past 10 years (eligible if ≥10 years without recurrence) or non-melanoma skin cancer within the past 5 years (eligible if ≥5 years without recurrence)
• Participation in another clinical trial within 60 days of baseline
• Unwilling to contact study staff before enrolling in other health-related research and avoid participating in any research that may interfere with this study.
• Currently following a restricted or weight-loss diet
• Prior bariatric surgery
• Intake of >14 alcoholic drinks/week and/or not willing to avoid alcohol consumption for 48 hours prior to test visits
• Principal Investigator discretion related to the potential participant's ability to adhere to the study requirements, including being able to come to attend visits
• Does not speak and/or understand English
• Unwilling to refrain from donating blood or plasma during the study
• Weight <110 lb
• If a potential participant takes thyroid medicine, abnormal thyroid stimulated hormone (TSH) concentration (TSH outside of normal range), or change in dose of thyroid medication within the last 6 months