This randomized, controlled, two-arm clinical study aims to determine how increasing the proportion of plant-based foods in the diet affects skeletal muscle strength, mass and function, protein metabolism, microbiota and key metabolic markers in healthy older men and women. We hypothesize that diets enriched with animal-based foods will maintain maximal quadriceps strength-the primary outcome of the study-more effectively after the 3-month nutritional intervention than plant-based diets. Proteomic analyses will be performed to identify molecular mechanisms and potential muscle biomarkers reflecting metabolic adaptations of skeletal muscle to plant-enriched diets. In addition, metabolic health markers and micronutrient status will be evaluated to better understand the overall health effects of dietary plant-based transition in older adults.
This exploratory, open-label, randomized, controlled, two-arm clinical study aims to evaluate how increasing the proportion of plant-based foods in the diet affects skeletal muscle health in older adults. The primary objective is to assess the impact of a plant-enriched diet on physical performance, specifically maximal quadriceps strength after a 3-month nutritional intervention. Secondary objectives are to determine the effects of a plant-enriched diet on: (1) whole-body and muscle protein metabolism, (2) modifications in the skeletal muscle proteome and metabolome, (3) functional capacities, (4) body composition, (5) gut microbiota composition, and (6) sex-related differences in metabolic adaptability. The study will compare diets containing different proportions of plant-based foods in healthy older men and women. Participants will undergo medical evaluation, nutritional follow-up, body composition measurements, muscle function testing, indirect calorimetry, and biological sampling including blood tests, and microbiota profiling. BBlood samples will be collected for proteomic and metabolomic analyses to identify molecular pathways and potential muscle biomarkers associated with adaptations to plant-enriched diets. In parallel, circulating amino acid concentrations will be measured to assess protein bioavailability, and blood samples will be incubated with skeletal muscle cells to evaluate the anabolic potential of the ingested proteins. Digestive tolerance, micronutrient status, and metabolic health markers will also be monitored. The procedures are associated with minimal anticipated risks. Blood sampling may cause bruising and indirect calorimetry may result in mild discomfort. Plant-enriched diets may induce transient digestive symptoms or weight loss, which will be closely monitored. Participants experiencing clinically significant weight loss will be withdrawn from the intervention and followed until stabilization. The findings of this study may strengthen public health recommendations promoting sustainable dietary transitions in older adults and help develop nutritional strategies aimed at maintaining optimal muscle health and supporting healthy aging.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
60
Participants follow a diet enriched in plant-based foods with approximately 70% of protein from plant sources and 30% from animal sources for 3 months, with tailored dietary guidance, meal planning support, and compliance monitored through food diaries and periodic follow-up.
Participants follow a standard diet with approximately 70% of protein from animal sources and 30% from plant sources for 3 months, with general nutritional guidance and compliance monitored through food diaries and periodic consultations.
CHU de Clermont-Ferrand
Clermont-Ferrand, France
Maximal Quadriceps Strength
Maximal voluntary contraction of the quadriceps muscle will be measured using a standardized dynamometer. This outcome evaluates the primary effect of the dietary intervention on skeletal muscle strength in older adults.
Time frame: Baseline and Month 3
Protein metabolism
Assessment of plasma amino acid concentrations, ex vivo anabolic response, proteomic and metabolic profiling, and related biomarkers (glucose, insulin, cytokines).
Time frame: Baseline and Month 3
Short Physical Performance Battery (SPPB) total score
Physical performance will be assessed using the Short Physical Performance Battery (SPPB), which combines balance, gait speed, and chair stand performance into a composite score ranging from 0 to 12 points. Higher scores indicate better physical function.
Time frame: Baseline and Month 3
Handgrip strength
Handgrip strength will be measured using a calibrated hand dynamometer. The maximum grip strength will be recorded and reported in kilograms (kg). Higher values indicate greater muscle strength.
Time frame: Baseline and Month 3
Distance covered during the 6-minute walk test
Functional exercise capacity will be assessed using the 6-minute walk test. The total distance walked during 6 minutes will be recorded and reported in meters (m). Higher values indicate better functional capacity.
Time frame: Baseline and Month 3
Appendicular lean mass
Appendicular lean mass will be assessed by dual-energy X-ray absorptiometry (DXA) and reported in kilograms (kg). Higher values indicate greater skeletal muscle mass.
Time frame: Baseline and Month 3
Relative abundance of dominant gut bacterial taxa
Description: Stool samples will be analyzed using microbiome sequencing methods. Relative abundance of predefined dominant bacterial taxa will be quantified and reported as percentages of total bacterial abundance.
Time frame: Baseline and Month 3
Sex-specific changes in maximal quadriceps strength
Quadriceps maximal voluntary contraction force will be measured using a standardized dynamometer and reported in Newtons (N). Changes from baseline will be compared between male and female participants to evaluate sex-specific responses to the dietary intervention.
Time frame: Baseline and Month 3
Sex-specific changes in serum metabolomic and proteomic profiles
Serum metabolomic and proteomic profiles will be analyzed using validated metabolomics and proteomics platforms. Changes in predefined metabolites and proteins will be compared between male and female participants to evaluate sex-specific responses to the dietary intervention.
Time frame: Baseline and Month 3
Sex-specific changes in appendicular lean mass
Appendicular lean mass will be assessed by dual-energy X-ray absorptiometry (DXA) and reported in kilograms (kg). Changes from baseline will be compared between male and female participants to evaluate sex-specific responses to the dietary intervention.
Time frame: Baseline and Month 3
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