The Effect of a 12-week Self-composed Vegan Diet With or Without Concurrent Resistance Exercise on Thigh Muscle Volume in Older Adults

Study Overview
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Brief Summary
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Consumers are increasingly encouraged to consume more plant-based foods and lower their consumption of foods from animal origin. This shift is driven by environmental and health factors. However, the consequences of such a transition on muscle mass still remains to be explored. This is of particular importance in the older population, where the age-related reduction in muscle mass and strength is highly prevalent. Adequate dietary intake, specifically protein intake, is a well-known strategy in promoting muscle mass in older adults. Plant-based foods are currently considered to be inferior to animal-based foods in their protein quality, and are therefore considered to be suboptimal for the maintenance of muscle mass at an older age. On the other hand, combining plant-based foods may improve the protein quality and thereby the anabolic properties of a vegan meal. Evidence regarding the anabolic properties of vegan diets in older adults is scarce. As such, the current study aims to assess 1) the effects of a 12-week self-composed vegan diet in comparison to an omnivorous diet on thigh muscle volume (TMV) in community-dwelling older adults and 2) the effect of a 12-week self-composed vegan diet combined with twice-weekly resistance exercise (RE) on TMV in comparison to a self-composed vegan diet without resistance exercise in community-dwelling older adults.

Official Title
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The Effect of a 12-week Self-composed Vegan Diet With or Without Concurrent Resistance Exercise on Thigh Muscle Volume in Older Adults

Conditions
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Vegan Diet, Sarcopenia, Cardiovascular Health, Osteoporosis, Gut Health

Intervention / Treatment
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* Other: Vegan diet
* Other: Resistance exercise
* Other: Omnivorous diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged ≥65 years old; Community-dwelling; BMI 25-32 kg/m2; Habitual diet contains animal-based food products (i.e. dairy, meat and/or fish) at least 5 days per week; Exclusion Criteria: Following a self-reported entirely vegetarian or vegan diet during the six months prior to the study; Following a prescribed high (≥1.2 g/kg/d) or low protein diet (<0.8 g/kg/d), and/or or taking protein supplements on medical advice, during the month prior to the study; Participating in a structured progressive resistance exercise training program the during three months prior to the study; ≥4 kg of body weight loss during three months before the start of the study; Being diagnosed with one of the following: diabetes mellitus; renal disease; neurological or neuromuscular disorders; serious cardiovascular diseases; cancer (with the exception of the following types of skin cancer: basal cell carcinoma, squamous cell carcinoma); (very) severe chronic obstructive lung disease (COPD; GOLD stage III or IV); bowel disease. Chronic use of medication that affects muscle function as assessed by the research physician; The use of anticoagulants incompatible for muscle biopsies as assessed by the research physician: acenocoumarol (sintrom); phenprocoumon (marcoumar); dabigatran (pradaxa); apixaban (eliquis); rivaroxaban (xarelto); clopidogrel (plavix); edoxaban (lixiana); combination of acetylsalicylic acid or carbasalate calcium (ascal) with dipyridamole; Having a contra-indication to MRI scanning (including, but not limited to): Pacemakers and defibrillators Infraorbital or intraocular metallic fragments Ferromagnetic implants Claustrophobia Not willing to stop nutritional supplements, with the exception of supplements on medical advice, and vitamin D; Not willing or afraid to give blood, undergo a muscle biopsy or have an MRI scan during the study; Unwilling to eat a self-composed vegan diet or an omnivorous diet with daily consumption of animal-based food sources for 3 months; Unwilling to participate in RE twice a week for 3 months; Currently a research participant in another trial or participated in a clinical trial during one month before the start of the measurement period; Not being able to understand Dutch; Not having a general physician; Working, or having a direct family member that work at the Division of Human Nutrition at Wageningen University during the study. Unwilling to be informed about incidental findings of pathology and approving of reporting this to their general physician.

Ages Eligible for Study
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Minimum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vegan group<br> | Other: Vegan diet<br>* A self-composed 12 week fully plant-based diet<br>|
| Experimental: Vegan group with resistance exercise<br> | Other: Vegan diet<br>* A self-composed 12 week fully plant-based diet<br>Other: Resistance exercise<br>* Biweekly resistance exercise for 12 weeks<br>|
| Active Comparator: Omnivorous group<br> | Other: Omnivorous diet<br>* Habitual diet containing both animal- and plant-based food products<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in thigh muscle volume | Thigh muscle volume of both legs will be assessed using magnetic resonance imaging before and after the 3-month intervention | 12 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body composition | Other body composition indices will also be measured using magnetic resonance imaging before and after the intervention. These indices include: liver fat fraction, thigh muscle fat infiltration, abdominal subcutaneous adipose tissue, visceral fat tissue. | Change after 12 weeks | 
| Change in muscle strength | Maximal isometric knee extension and flexion strength of both legs will be measured using Biodex. | Change after 12 weeks | 
| Muscle fractional synthesis rates | Muscle fractional synthesis rates, expressed as daily fractional synthesis rates (FSR, %/day), will be assessed using a deuterium oxide protocol. Daily FSR will be calculated using the 2^H-alanine enrichment in plasma and the mixed muscle-bound 2^H-alanine enrichment. | 10 days | 
| Change in bone mineral density | Measured using a Dual X-Ray Absorptiometry dual femur scan | Change after 12 weeks | 
| Change in fasting bone turnover markers | Serum procollagen type I N-terminal propeptide (P1NP) will be measured for bone formation and C-terminal telopeptide of type I collagen (CTX) for bone resorption. | Change after 6 and 12 weeks | 
| Change in plasma insulin growth factor 1 levels | Fasting serum insulin-like growth factor 1 (IGF-1) | Change after 6 and 12 weeks | 
| Change in plasma parathyroid hormone (PTH) levels | Fasting plasma PTH | Change after 6 and 12 weeks | 
| Change in fasting plasma insulin levels | Fasting plasma insulin | Change after 6 and 12 weeks | 
| Change in metabolic profile | Fasting plasma levels of multiple metabolites | Change after 6 and 12 weeks | 
| Change in fasting blood pressure | Fasting systolic and diastolic blood pressure | Change after 6 and 12 weeks | 
| Change in haemoglobin levels | Fasting plasma haemoglobin levels | Change after 12 weeks | 
| Change in vitamin B12 status | Fasting plasma methylmalonic acid levels | Change after 12 weeks | 
| Change in vitamin D status | Fasting serum vitamin D levels | Change after 12 weeks | 
| Change in gastro-intestinal symptoms | Self-reported gastro-intestinal symptoms using the gastro-intestinal symptom rating scale. The questionnaire includes 15 questions covering 5 common symptom clusters on a 7-point likert scale ranging from no symptoms (minimum) to severe symptoms (maximum). A higher score indicates worse symptoms. | Change after 12 weeks | 
| Untargeted gut metabolomics | Untargeted gut metabolomics will be performed on fasting plasma samples | Change after 12 weeks | 
| Change in fasting plasma high-sensitive C-reactive protein (hs-CRP) | Fasting plasma hs-CRP | Change after 6 and 12 weeks | 
| Change in ferritin levels | Fasting plasma ferritin levels | Change after 12 weeks | 
| Tryptophan | Tryptophan will be assessed using targeted metabolomics on plasma samples | Change after 12 weeks | 
| Tyrosine | Tyrosine will be assessed using targeted metabolomics on plasma samples | Change after 12 weeks | 
| Branch-chained amino acids | Branch-chained amino acids will be assessed using targeted metabolomics on plasma samples | Change after 12 weeks | 
| Oxidized amino acids | Oxidized amino acids will be assessed using targeted metabolomics on plasma samples | Change after 12 weeks | 
| Gut metagenomics | Microbial DNA will be isolated from the feces samples. The taxonomy and function of specific genes will be assessed via metagenomic sequencing on the microbial DNA. | Change after 12 weeks |