Protein-rich foods may improve brain insulin-sensitivity, which is important for cognitive and metabolic health, and may also translate into an improved food intake regulation. It is therefore pertinent to delineate the effects of plant-derived proteins, which are a more sustainable alternative to animal-derived proteins, on brain insulin-sensitivity and related functional benefits. The hypothesis is that daily plant-derived or animal-derived protein supplementation improves brain vascular function and insulin-sensitivity, thereby improving cognitive performance and appetite control in overweight or obese older men and women.
The primary objective is to investigate in overweight or obese older adults the effect of daily protein supplementation for two weeks with either a plant-derived protein or an animal-derived protein on vascular function and insulin-sensitivity in the brain, while changes in cognitive performance and appetite-related brain reward activity will also be evaluated (secondary study 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 gold standard magnetic resonance imaging (MRI)-perfusion method Arterial Spin Labeling (ASL).
Men and women, aged between 60-75 years (older adults)
BMI between 25-35 kg/m2 (overweight or obese)
Fasting plasma glucose < 7.0 mmol/L
Fasting serum total cholesterol < 8.0 mmol/L
Intolerant to milk products or fava bean allergy
Vegetarians
Left-handedness
Current smoker, or smoking cessation < 12 months
Crossover
Protein supplementation with an animal-based protein isolate
Dietary supplementStudy participants will consume, in random order, twice daily (2 x \~20 g) a plant protein (fava bean protein isolate), animal protein (milk protein isolate) or control (cornstarch providing no extra protein)
Protein supplementation with a plant-based protein isolate
Dietary supplementStudy participants will consume, in random order, twice daily (2 x \~20 g) a plant protein (fava bean protein isolate), animal protein (milk protein isolate) or control (cornstarch providing no extra protein)
Control arm - cornstarch
Other interventionStudy participants will consume, in random order, twice daily (2 x \~20 g) a plant protein (fava bean protein isolate), animal protein (milk protein isolate) or control (cornstarch providing no extra protein)
Cerebral blood flow responses before (brain vascular function) and after the administration of intranasal insulin spray (brain insulin-sensitivity)
Cognitive performance
Cognitive performance will be assessed with a neuropsychological test battery
Appetite-related brain reward activity
Blood oxygenation level-dependent (BOLD)-functional MRI (fMRI) response to food cues
Transcranial Doppler ultrasound
Blood flow velocity in the MCA
Blood pressure
Office BP (SBP and DBP) measured in mmHg
Heart rate
Heart rate (HR) measured in beats/min
Metabolic risk markers - Fasting lipids
Fasting lipids: * Fasting serum triacylglycerol (TAG) concentrations in mmol/L will be measured * Fasting serum total cholesterol (TC) and HDL-C in mmol/L will be measured
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Maastricht University Medical Center
Lead sponsor
Cosun
Collaborator
