Effects of Alpha-lactalbumin Intake on Metabolic and Cognitive Functions in Elderly
- Conditions
- Mild Cognitive Impairment
- Interventions
- Dietary Supplement: Alpha-lactalbuminDietary Supplement: WheyDietary Supplement: Casein
- Registration Number
- NCT02082418
- Lead Sponsor
- Texas A&M University
- Brief Summary
Aging modifies the metabolic pathway of the neurotransmitter serotonin by reducing the synthesis rate and increasing the breakdown rate of serotonin, possibly related to the observed enhanced sensitivity of the serotonergic pathway. Since serotonin plays a prominent role in neuropsychological functions such as anxiety, mood and memory, the enhanced sensitivity of the serotonergic pathway in aging can probably explain the fact that elderly are more vulnerable to develop cognitive deficits and depressive symptoms.
Serotonin synthesis in brain is regulated by its precursor tryptophan (TRP). Because tryptophan is an essential amino acid, modifying the availability of tryptophan through dietary intake, can directly influence central serotonin metabolism and consequently affective and cognitive processes.
The aim of this study is to test the hypothesis that an acute intake of whey protein with high levels of TRP such as alpha-lactalbumin can stabilize the metabolism of serotonin and subsequently enhance metabolic and cognitive functions in healthy older adults. The acute effects of this dietary protein will be investigated in subjects with mild cognitive impairment (MCI), or dementia, compared to control subjects in order to examine whether healthy older subject with MCI benefit more from the intake of alpha-lactalbumin and/or whey. The investigators will investigate if this meal can optimize serotonin metabolism by elevating plasma TRP levels and plasma TRP appearance and enhance splanchnic TRP extraction. In addition, the effects on mood and cognitive functions will be examined.
- Detailed Description
The study involves for all subjects 3 test days (approximately 8 hours each). On this test day the investigators will examine the acute effects of a protein meal. Subjects will receive a mixture of alpha-lactalbumin and/or whey and/or casein, carbohydrates and amino acid stable isotopes to investigate protein and amino acid kinetics (assigned to alpha-lactalbumin or whey or casein group on test day 1, then switch on test day 2 and 3). The subjects will receive these stable isotopes by infusion in their blood and by oral intake (e.g. simultaneously with protein meal). For study purposes, blood will be drawn approx. 25 times during 8 hours on the test day, altogether about 100-120 ml of blood will be drawn on the test day.
Recruitment & Eligibility
- Status
- UNKNOWN
- Sex
- All
- Target Recruitment
- 59
Not provided
- Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (for healthy control group only)
- Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
- Indication of severe cognitive impairment (MOCA score < 17)
- Established diagnosis of Insulin Dependent Diabetes Mellitus
- History of untreated metabolic disease(s) including hepatic or renal disorder
- Presence of acute illness or metabolically unstable chronic illness
- Presence of fever within the last 3 days
- Preplanned surgery of procedures that would interfere with the conduct of the study
- Any other condition according to the PI or study physician that would interfere with proper conduct of the study / safety of the patient
- Current alcohol or drug abuse
- Known allergy to milk or milk products
- Use of long-term oral corticosteroids or short course of oral corticosteroids 4 weeks preceding first test day
- Use of protein or amino acid containing nutritional supplements within 5 days of test day
- (Possible) pregnancy
- BMI of < 18.5 or ≥ 40 kg/m2
- Dietary or lifestyle characteristics: When during the period from enrollment to completion of the study (end of test day) any condition is developed, whether causing the subject to not meet inclusion criteria or to meet exclusion criteria, the subject will be excluded from the study
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description Healthy Whey healthy control subjects MCI Casein mild cognitive impariments MCI Whey mild cognitive impariments Healthy Alpha-lactalbumin healthy control subjects Healthy Casein healthy control subjects MCI Alpha-lactalbumin mild cognitive impariments Dementia Whey established diagnosis of dementia Dementia Casein established diagnosis of dementia Dementia Alpha-lactalbumin established diagnosis of dementia
- Primary Outcome Measures
Name Time Method Net whole-body protein synthesis 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal Change in whole-body protein synthesis rate after intake of meal
- Secondary Outcome Measures
Name Time Method Taurine turnover rate Postabsorptive state during 3 hours Enrichment of taurine in plasma
Citrulline rate of appearance Postabsorptive state during 2 hours Plasma enrichment of citrulline
Protein digestion after feeding 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal Ratio enrichment free phenylalanine versus phenylalanine from protein spirulina
Insulin response to feeding During 3 hours after feeding Acute change from postabsorptive state after intake of meal
Arginine turnover rate Postabsorptive state during 3 hours Arginine enrichment in plasma
Glycine rate of appearance Postabsorptive state during 3 hours Glycine enrichment in plasma
Tryptophan turnover rate Postabsorptive state during 3 hours and change after feeding Tryptophan enrichment in plasma in postabsorptive state and after intake of meal
Myofibrillar protein breakdown rate 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal 3methylhistidine enrichment in plasma
Skeletal and respiratory muscle strength 1 day Difference in leg strength and fatigue, handgrip strength and fatigue, and inspiratory and expiratory pressure between older adults with and without MCI.
Cognitive function and mood Postabsorptive state during 3 hours and change after feeding Outcome of neuro-psychological tests in healthy older adults with and without MCI in relation to the tryptophan metabolism
Whole body collagen breakdown rate Postabsorptive state during 3 hours Hydroxyproline enrichment in plasma
Fat-free mass Postabsorptive state during 15 min Characteristics of study subjects
Trial Locations
- Locations (1)
Texas A&M University
🇺🇸College Station, Texas, United States