Almonds and Health Effects on Metabolism, Vascular Function and Cognition

Study Overview
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Brief Summary
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The primary objective of the proposed study is to examine and understand the impact of long-term almond consumption on chronic glucose metabolism in subjects with impaired glucose tolerance and/or impaired fasting glucose.

Detailed Description
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Objectives: Secondary objectives are to investigate if improved chronic glucose metabolism in subjects with impaired glucose tolerance and/or impaired fasting glucose after long-term almond consumption translates into improved peripheral and brain vascular function, and enhanced cognitive performance. In addition, the investigators will address to what extent improved chronic glucose metabolism in subjects with impaired glucose tolerance and/or impaired fasting glucose after long-term almond consumption can be explained by (combined) effects of lowered hepatic lipid accumulation and inflammation, skeletal muscle characteristics, visceral and subcutaneous fat accumulation, pancreatic function or fecal microbiota composition. Study design: The proposed study will be a 12 months randomised, controlled trial with a cross-over design. Two experimental periods of five months will be separated by a two months washout period. Study population: Forty-three impaired glucose tolerant and/or impaired fasting glucose subjects, with overweight and mild obesity (BMI 25-35 kg/m2), aged 40-70 years. Intervention: During the intervention period of 5 months, subjects will receive daily 50 gr almonds, but not in the 2 months washout and 5 months control periods.

Official Title
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Effects of Almond Consumption on Chronic Glucose Regulation, Vascular Function and Cognitive Performance: The AL-INCLUSIVE Trial

Conditions
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PreDiabetes, Impaired Glucose Tolerance, Impaired Fasting Glucose, Overweight and Obesity

Intervention / Treatment
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* Dietary Supplement: Almonds


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged between 40-70 years Men and women BMI between 25-35 kg/m2 (overweight and obese) Being classified as having impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG). IGT is defined according the criteria of the WHO and American Diabetes Association (ADA) as two-hour glucose concentrations of 7.8 to 11.0 mmol/l (140 to 199 mg per dL) during the 75-g oral glucose tolerance test. IFG is defined as having a fasting plasma glucose between 6.1 and 7.0 mmol/l (110 to 125 mg per dL) and a two-hour glucose concentration below 7.8 mmol/l (140 mg per dL). Serum total cholesterol < 8.0 mmol/L (further testing is recommended for excessive hyperlipidemia [serum total cholesterol ≥ 8.0 mmol/L] according to the Standard for cardiovascular risk management of the Dutch general practitioners community [NHG]) Serum triacylglycerol < 4.52 mmol/L No current smoker No diabetic patients No familial hypercholesterolemia No abuse of drugs Not more than 4 alcoholic consumption per day with a maximum of 21 per week Stable body weight (weight gain or loss < 3 kg in the past three months) No use of medication known to treat blood pressure, lipid or glucose metabolism No use of an investigational product within another biomedical intervention trial within the previous 1-month No severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases and rheumatoid arthritis No active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident Willingness to give up being a blood donor from 8 weeks before the start of the study, during the study and for 4 weeks after completion of the study No difficult venipuncture as evidenced during the screening visit Willing to comply to study protocol during study Informed consent signed Exclusion Criteria: Allergy or intolerance to almonds Serum total cholesterol ≥ 8.0 mmol/L Serum triacylglycerol ≥ 4.52 mmol/L Current smoker, or smoking cessation <12 months Diabetic patients Familial hypercholesterolemia Abuse of drugs More than 4 alcoholic consumptions per day or 21 per week Unstable body weight (weight gain or loss > 3 kg in the past three months) Use medication known to treat blood pressure, lipid or glucose metabolism Use of an investigational product within another biomedical intervention trial within the previous 1-month Severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases and rheumatoid arthritis Active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident Not willing to give up being a blood donor from 8 weeks before the start of the study, during the study or for 4 weeks after completion of the study Not or difficult to venipuncture as evidenced during the screening visit Use of over-the-counter and prescribed medication or supplements, which may interfere with study measurements to be judged by the principal investigator; Use of oral antibiotics in 40 days or less prior to the start of the study; Blood donation in the past 3 months before the start of the study Not willing to comply to study protocol during study or sign informed consent

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control<br>No almonds | |
| Experimental: Experimental<br>Almonds | Dietary Supplement: Almonds<br>* During the intervention period of 5 months, subjects will receive daily 50 gr almonds. Subjects are free to consume the almonds during the day whenever they want to, i.e. there will not be guidelines when to consume the almonds.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin sensitivity | Glucose infusion rate during a hyper-insulinemic euglycemic clamp. | Change from control period (week 22 and week 52) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose concentrations | Fasting plasma glucose concentrations will be determined in blood samples. | Glucose will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| Markers for fasting lipid metabolism | Markers for fasting lipid metabolism include serum total cholesterol (mmol/L), HDL cholesterol (mmol/L), and triacylglycerol (mmol/L) concentrations. | These markers will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| LDL cholesterol concentrations | Fasting LDL cholesterol concentrations will be determined in blood samples using the Friedewald equation. | These markers will be calculated from measurements at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| C-reactive protein concentrations | Concentrations of CRP will be determined in blood samples. | CRP will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| Blood pressure | Systolic and diastolic blood pressure. | Blood pressure will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| Body weight | Body weight in kg. | Body weight will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| Body circumferences | Waist and hip circumferences. | Waist and hip circumferences will be measured at week 0, week 5, week 10, week 21, week 22, week 30, week 35, week 40, week 51, week 52 | 
| Pulse Wave Analysis | Vascular function (arterial stiffness). | Change from control period (week 21 and week 51) | 
| Pulse Wave Velocity | Vascular function (arterial stiffness). | Change from control period (week 21 and week 51) | 
| Retinal microvascular caliber | Arteriovenous ratio and diameter of retinal arterioles and venules will be measured by retinal microvascular imaging. | Change from control period (week 21 and week 51) | 
| Cognitive performance | Cambridge Neuropsychological Test Automated Battery. | Cognition will be tested at week 0, week 10, week 21, week 30, week 40, week 51. | 
| Markers for low-grade systemic inflammation | Markers for low-grade systemic inflammation include IL-6, IL-8, TNF-alpha and SAA. | Change from control period (week 21 and week 51) | 
| Markers for endothelial dysfunction | Markers for endothelial dysfunction include sVCAM-1, sICAM-1 and soluble E-selectin. | Change from control period (week 21 and week 51) | 
| Markers for postprandial lipid metabolism | Markers for postprandial lipid metabolism include triacylglycerol (mmol/L) and NEFA concentrations. | Change from control period (week 21 and week 51) | 
| Markers for fasting and postprandial glucose and insulin metabolism | Markers for fasting and postprandial glucose and insulin metabolism include plasma glucose, serum insulin, C-peptide and HbA1c concentrations. Also HOMA-IR will be calculated. | Change from control period (week 21 and week 51) | 
| Markers for liver function | Markers for liver function include ALAT and ASAT concentrations. | Change from control period (week 21 and week 51) | 
| Markers for nerve growth | Markers for nerve growth include BDNF concentrations. | Change from control period (week 21 and week 51) | 
| Markers for advanced glycation endproducts | Markers for advanced glycation endproducts include dicarbonyl, CML, CEL and MG-H1 concentrations. | Change from control period (week 21 and week 51) | 
| Nitric oxides concentrations | Concentrations of NOx will be determined in blood samples. | Change from control period (week 21 and week 51) | 
| Cerebral blood flow | Arterial Spin labeling will be performed to determine cerebral blood flow. | Change from control period (week 22 and week 52) | 
| Fat distribution in abdomen | Magnetic Resonance Imaging measurements will be included to quantify abdominal fat compartments (i.e. subcutaneous and visceral fat) and fat content of abdominal organs (i.e. liver and pancreas). | Change from control period (week 22 and week 52) | 
| Biopsies adipose tissue | Fat biopsies to examine fat cell size and inflammation in adipose tissue. | Change from control period (week 22 and week 52) | 
| Biopsies muscle tissue | Muscle biopsies to examine mitochondrial function. | Change from control period (week 22 and week 52) | 
| Lipid oxidation | Energy expenditure and substrate metabolism will be calculated from measurements via indirect calorimetry during the postprandial test. | Indirect calorimetry will be performed at week 21, week 22, week 51, week 52 at several time slots. | 
| Glucose oxidation | Energy expenditure and substrate metabolism will be calculated from measurements via indirect calorimetry during the postprandial test. | Indirect calorimetry will be performed at week 21, week 22, week 51, week 52 at several time slots. | 
| Blood pressure profiles | Blood pressure profiles will be measured for 48 hr via a Mobil-O-Graph. | Change from control period (week 21 and week 51) | 
| Glucose profiles | Glucose profiles will be measured for 48 hr using the FreeStyle Libre Pro. | Change from control period (week 21 and week 51) | 
| Physical activity profiles | Physical activity patterns will be monitored for 48 hr with the MOX device. | Change from control period (week 21 and week 51) | 
| Microbiota composition | Fecal samples to be used for analysing microbiota composition will be collected. | Change from control period (week 21 and week 51) | 
| General well-being | Quality of life and Affect grid questionnaires will be assessed. | General well-being will be tested at week 0, week 10, week 21, week 30, week 40, week 51. | 
| Food frequency | Food frequency questionnaire will be assessed. | Food frequency will be tested at week 0, week 10, week 21, week 30, week 40, week 51. | 
| Skinfold measurements | Calliper testing for determining body fat composition. | Change from control period (week 22 and week 52) |