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Evidence-Based Supplement Research
Evidence-Based Supplement Research
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Soy Protein and Improved Walking Speed

Research synthesisLow evidenceModerate effect3 studies · 3 beneficial · 0 neutral · 0 harmful

Across all 3 available studies, soy protein supplementation showed beneficial moderate-sized effects on walking speed, with all 3 studies reporting statistically significant improvements. Effects were typically observed at 8-12 weeks (median study duration 87 days). The most-studied dose was 14.5 g/day in one of the trials, though dosing was not consistently reported across all studies. Evidence primarily comes from elderly or pre-frail/frail older adult populations.

  • Effective dose range: ~14.5 g/day
  • Studied populations: elderly adults, pre-frail and frail elderly, middle-aged and older individuals undergoing resistance training

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (studies with null results are less likely to be published or indexed). The network meta-analysis (2024) ranked soy protein as less effective than whey for walking speed, suggesting soy may not be the most effective protein source. The two individual RCTs were in Japanese and community-dwelling elderly populations, which may limit generalizability to other groups. Soy protein was typically co-administered with resistance training or exercise, making it difficult to isolate the independent effect of soy protein alone.

Generated May 13, 2026
Doses used in studies
  • g/day: 14.5 (median 14.5, IQR 14.5–14.5) — 1 study
Time to effect
Median: 2.9 months · IQR 2.9 months–3 months · Range 2.8 months–3 months — Reported in 2 of 3 studies
3 of 3 papers
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