A two-period randomized crossover study will be conducted to evaluate the effect of nighttime pistachio consumption (i.e., after dinner and before sleep) on fasting blood sugar levels, longer-term blood sugar control, and risk factors for heart disease. This study will also investigate how pistachios affects gut health.
A two-period randomized crossover trial will be conducted. Participants will be randomized to receive each treatment for 12 weeks followed by a minimum 4-week wash-out period. During the pistachio treatment, participants will consume two ounces per day (57 g) of pistachios as an evening snack. During the control phase subjects will be given advice to consume 1-2 exchanges of carbohydrate as an evening snack, which is consistent with usual care. Markers of glycemic control, cardiovascular risk factors and gut health will be assessed at the beginning and the end of each treatment period.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
66
Unsalted pistachios
Advice and resources will be provided
Pennsylvania State University
University Park, Pennsylvania, United States
Fasting plasma glucose concentration
Fasting blood glucose (mg/dL)
Time frame: 12 weeks
HbA1c
HbA1c (%) will be assessed at the beginning and end of each treatment period
Time frame: 12 weeks
Serum insulin concentration (mIU/L)
fasting serum insulin levels assessed by blood draw
Time frame: 12 weeks
Peripheral systolic and diastolic blood pressure (mm Hg)
Blood pressure measured assessed using a SphymoCor Xcel (Atcor Medical).
Time frame: 12 weeks
Central systolic and diastolic blood pressure (mm Hg)
Blood pressure measured assessed using a SphymoCor Xcel (Atcor Medical).
Time frame: 12 weeks
Carotid-femoral pulse wave velocity (m/s)
A measure of arterial stiffness assessed using a SphymoCor Xcel (Atcor Medical). A higher percentage value is indicative of greater arterial stiffness.
Time frame: 12 weeks
Augmentation Index (%)
A measure of arterial stiffness assessed using a SphymoCor Xcel (Atcor Medical). A higher percentage value is indicative of greater arterial stiffness.
Time frame: 12 weeks
LDL cholesterol concentration (mg/dL)
Assessed using fasting blood draw
Time frame: 12 weeks
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HDL cholesterol concentration
Assessed using fasting blood draw
Time frame: 12 weeks
Total cholesterol concentration
Assessed using fasting blood draw
Time frame: 12 weeks
Triglyceride concentration
Assessed using fasting blood draw
Time frame: 12 weeks
HOMA-IR
Assessed using fasting blood draw and standardized HOMA-IR calculation. Fasting plasma glucose multiplied by fasting plasma insulin divided by 405.
Time frame: 12 weeks
waist circumference (cm)
Measured 10 cm above the navel
Time frame: 12 weeks
body weight (lbs)
Assessed using calibrated scale in Clinical Research Center
Time frame: 12 weeks
Diet quality: Healthy Eating Index 2015
Assessed using the Healthy Eating Index 2015
Time frame: 12 weeks
Change in the composition of the gut microbiome
microbiome composition assessed using fecal collection kit
Time frame: 12 weeks