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| Name | Class |
|---|---|
| California Walnut Commission | OTHER |
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Rationale: Healthy foods, including mixed nuts, may improve brain function, which is essential for cognitive and metabolic health, and may contribute to improved food intake regulation. It is therefore important to investigate the specific effects of walnuts on cerebral blood flow responses before and after intranasal insulin administration, as well as their associated functional benefits. The investigators hypothesize that long-term walnut consumption improves vascular function and insulin-sensitivity in the brain, thereby enhancing cognitive performance and appetite control in abdominally obese men and women. Objective: The primary objectives are to investigate in abdominally obese adults the effects of 24-week walnut consumption on (regional) vascular function and insulin-sensitivity in the brain, while the investigators will also assess changes in cognitive performance and appetite-related brain reward activity (secondary objectives). Cerebral blood flow responses before (brain vascular function) and after the administration of intranasal insulin spray (brain insulin-sensitivity) will be quantified by the non-invasive gold standard magnetic resonance imaging (MRI)-perfusion method Arterial Spin Labeling (ASL). Study design: This intervention study will have a randomized, controlled parallel design. The total study duration will be 24 weeks. Study population: Fifty-five abdominally obese men and (postmenopausal) women (aged 45-75 years) without a history of cardiovascular diseases or complaints will participate. This study population is expected to have a decreased cerebral blood flow at baseline and are also at increased risk of cognitive impairment, allowing for improvement by the intervention. Intervention: Study participants will receive daily 50 g (about 15% of energy) of raw walnuts (walnut intervention) or no walnuts (control intervention) for 24 weeks. Main study parameters/endpoints: At baseline and after 24 weeks (follow-up), participants will visit the research facilities for assessments. The primary endpoint is the difference in the cerebral blood flow response before and after intranasal insulin administration between the walnut and control intervention. Cognitive performance will be assessed, while the investigators will also focus on appetite-related brain reward activity (secondary outcomes).
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Walnut | Experimental | Receive 50g walnuts per day |
|
| Control | No Intervention | Does not receive walnuts and is supposed to refrain from nut consumption |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Walnuts | Dietary Supplement | 24-week consumption of 50 g/day of walnuts as part of a healthy diet according to the Dutch dietary guidelines |
|
| Measure | Description | Time Frame |
|---|---|---|
| Cerebral blood flow (CBF) prior to and after application of intranasal insulin | CBF will be non-invasively measured using the gold-standard methodology pseudo-continuous arterial spin labeling magnetic resonance imaging (pCASL MRI) | From enrollment to the end of treatment at 24 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| Bloodoxygen level-dependent (BOLD) functional MRI (fMRI) activity to measure appetite-related brain reward activity | BOLD fMRI activity will be measured before and while participants watch food pictures | From enrollment to the end of treatment at 24 weeks |
| Cognitive performance |
| Measure | Description | Time Frame |
|---|---|---|
| Endothelial function - Flow Mediated Dilation | Changes in diameter during Flow-Mediated Dilation (FMD) of the brachial artery will be assessed using ultrasound. | From enrollment to the end of treatment at 24 weeks. |
| Endothelial function - Carotid Artery Reactivity |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Peter J. Joris, PhD | Contact | +31883887250 | p.joris@maastrichtuniversity.nl | |
| Linda J. Kehr, MSc | Contact | +31433883931 | linda.kehr@maastrichtuniversity.nl |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Maastricht University, Department of Nutrition and Movement Sciences | Maastricht | Limburg | 6200MD | Netherlands |
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| ID | Term |
|---|---|
| D056128 | Obesity, Abdominal |
| D060825 | Cognitive Dysfunction |
| ID | Term |
|---|---|
| D009765 | Obesity |
| D050177 | Overweight |
| D044343 | Overnutrition |
| D009748 | Nutrition Disorders |
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Cognitive performance measurement of the following cognitive domains: memory, executive function and psychomotor speed. Measurements will be performed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). |
| From enrollment to the end of treatment at 24 weeks. |
Changes in diameter during Carotid Artery Reactivity (CAR) in response to a cold stressor will be assessed using ultrasound |
| From enrollment to the end of treatment at 24 weeks. |
| Markers related to arterial stiffness | Pulse Wave Analysis (PWA) of the radial artery and Femoral-to-carotid Pulse Wave Velocity (PWV) in m/s will be measured with a tonometer using Sphygomocor | From enrollment to the end of the intervention at 24 weeks. |
| Peripheral insulin sensitivity | 7-point oral glucose tolerance test (OGTT) to determine insulin sensitivity based on insulin and glucose concentrations, Matsuda index and 2h glucose tolerance (2h glucose concentrations) | From enrollment to the end of the intervention at 24 weeks. |
| Brain perfusion | Cerebral blood flow velocity (CBFv) of the medial cerebral artery will be measured with transcranial Doppler ultrasound (TCD) | From enrollment to the end of treatment at 24 weeks. |
| Markers related to gut microbiota activity | Fecal and fasting plasma short-chain fatty acids (acetate, butyrate, propionate), fecal bile acids (cholic acid, chenodeoxycholic acid, doxycholic acid, lithocholic acid), fecal lipid (non-esterified fatty acids, triacylglycerides, total cholesterol) | From enrollment to the end of treatment at 24 weeks. |
| Perceived hunger and satiety | Visual analogue scales (VAS) questionnaires | From enrollment to the end of treatment at 24 weeks. |
| Mental health | Beck Depression Inventory (BDI), State-Trait Anxiety Inventories (STAI) | From enrollment to the end of the intervention at 24 weeks. |
| Mood | Profile of Mood States (POMS) questionnaire | From enrollment to the end of the intervention at 24 weeks. |
| Stress | Perceived Stress Scale (PSS) questionnaire | From enrollment to the end of the intervention at 24 weeks. |
| Sleep characteristics | Pittsburgh Sleep Quality Index (PSQI) questionnaire to assess sleep duration, quality, latency, and efficiency | From enrollment to the end of the intervention at 24 weeks. |
| Office blood pressure | Office blood pressure and heart rate | From enrollment to the end of the intervention at 24 weeks. |
| 24h ambulatory blood pressure | 24h ambulatory blood pressure measured every 15 min | From enrollment to the end of the intervention at 24 weeks. |
| Lipid metabolism | Circulating triacylglycerol, High-Density Lipoprotein (HDL) cholesterol, Low-Density Lipoprotein (LDL) cholesterol, and Total Cholesterol concentrations | From enrollment to the end of the intervention at 24 weeks" |
| Markers related to low-grade systemic inflammation | Interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)a, monocyte chemo attractant protein (MCP)-1, C-reactive protein (hsCRP) and serum amyloid A (SAA) | From enrollment to the end of the intervention at 24 weeks. |
| Markers related to arterial stiffness | Pulse Wave Velocity (PWV) in m/s measured with a tonometer using Sphygomocor | From enrollment to the end of the intervention at 24 weeks. |
| Structural brain status | High-resolution anatomical MPRAGE scan | From enrollment to the end of the intervention at 24 weeks. |
| Body Composition - Fat Mass | BodPod will be used to measure fat mass (weight) | From enrollment to the end of the intervention at 24 weeks. |
| Body Composition - Fat Free Mass | BodPod will be used to measure fat free mass (weight). | From enrollment to the end of treatment at 24 weeks. |
| Ad libitum food intake - weight | Ad libitum food intake (weight) in the fasted state | From enrollment to the end of the intervention at 24 weeks. |
| Ad libitum food intake - Caloric content | Ad libitum food intake (caloric content) in the fasted state. | From enrollment to the end of the intervention at 24 weeks. |
| Satiety hormones related to food intake | Plasma levels of GLP-1 before and after ad libitum food intake at time points 0, 15, 30, 60, 90 minutes. | From enrollment to the end of the intervention at 24 weeks. |
| Retinal microvasculature | Retinal microvascular calibers will be measured using retinal images made with a fundus camera | From enrollment to the end of the intervention at 24 weeks. |
| Weight | Weight in kilograms | From enrollment to the end of the intervention at 24 weeks. |
| Waist circumference | Waist circumference in centimeters | From enrollment to the end of the intervention at 24 weeks. |
| Hip circumference | Hip circumference in centimeters | From enrollment to the end of the intervention at 24 weeks. |
| Food intake | Food intake will be assessed using the Food Frequency Questionnaire | From enrollment to the end of the intervention at 24 weeks. |
| D009750 |
| Nutritional and Metabolic Diseases |
| D001835 | Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D003072 | Cognition Disorders |
| D019965 | Neurocognitive Disorders |
| D001523 | Mental Disorders |