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Phosphatidylserine and endurance performance: grade C

Limited evidence. Direction: Benefit.

C LimitedSingle research groupShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: C: 1 small RCT

One double-blind trial in 14 active men found longer time to exhaustion at 85% VO2max after 750 mg a day of soy PS for 10 days, with no change on placebo; the authors describe it as the first such report. A companion trial from the same group in 8 men found no reduction in muscle soreness or damage markers after downhill running. No independent replication was found.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)200520102015Crossover RCTControlled trialKingsley 2006, 2006: controlled trial, n = 14, result not recordedKingsley 2006, 2006: crossover RCT, n = 8, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Kingsley 20062006crossover RCT8result not recorded
Kingsley 20062006controlled trial14result not recorded

Phosphatidylserine supplementation and recovery following downhill running.

Kingsley MI, Kilduff LP, McEneny J. Phosphatidylserine supplementation and recovery following downhill running Med Sci Sports Exerc, 2006. PMID 16960523

Result not recorded
Design
Double-blind, placebo-controlled crossover trial (soy PS 750 mg/day)
Sample
n = 8
Population
Recreationally active men, downhill running
Funding
not stated

Effects of phosphatidylserine on exercise capacity during cycling in active males.

Kingsley MI, Miller M, Kilduff LP. Effects of phosphatidylserine on exercise capacity during cycling in active males Med Sci Sports Exerc, 2006. PMID 16394955

Result not recorded
Design
Double-blind, placebo-controlled trial, 10 days (soy PS 750 mg/day)
Sample
n = 14
Population
Active men, intermittent cycling
Funding
not stated

Search and history

Search (): phosphatidylserine[ti] AND (exercise[tiab] OR performance[tiab] OR athletes[tiab]) AND (randomized controlled trial[pt] OR clinical trial[pt] OR review[pt])

  • Graded C (proposed): Proposed in the monograph draft
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page