The Study
Impact of increased protein intake in older adults: a 12-week double-blind randomised controlled trial.
This study is like a fair test where people were randomly given different kinds of protein shakes and then checked to see if they got stronger. Because it was fair and no one knew who got what, we can trust that if there was a real difference, we’d see it. But we didn’t see any difference — so we can say this amount of protein didn’t help in this case.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave older adults a daily shake with 20g of protein — either from plants or milk — to see if it made them stronger or healthier.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 571 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The small grip strength increase likely came from repeating the test, not the protein — meaning the shakes didn't help.
- 2After 12 weeks, everyone got a little stronger in their grip — but it didn't matter if they drank plant or milk protein or no extra protein at all.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Age and ageing
Year
2024
Authors
Janine Wirth, Annalisa Segat, K. Horner, Domenico Crognale, Thomas L. Smith, M. O'Sullivan, Lorraine Brennan
Related Content
Claims (6)
Consuming more protein results in greater gains in muscle mass and strength, and these gains are larger than the biological effects caused by activation of the mTOR pathway.
Taking 20 grams of protein daily for 12 weeks from plant or dairy sources does not change handgrip strength, leg strength, body composition, metabolic biomarkers, sleep quality, or health-related quality of life in healthy adults aged 50 and older compared to a low-protein diet with the same number of calories.
Taking 20 grams of protein per day for 12 weeks does not change sleep quality in healthy older adults, regardless of whether the protein comes from milk, meat, or plants.
Taking 20 grams of protein per day for 12 weeks does not change health-related quality of life in healthy older adults, as measured by the SF-36 questionnaire, no matter what type of protein is used.
In healthy older adults, taking 20 grams of plant-based protein daily for 12 weeks results in the same change in muscle strength as taking 20 grams of dairy-based protein daily for 12 weeks.
In healthy older adults, handgrip strength increases slightly over 12 weeks even without protein supplements, and this change is likely due to factors like repeated testing or seasonal changes.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.