Phosphatidic Acid
Also called PA, soy phosphatidic acid, Mediator PA, PAS (phosphatidylserine-phosphatidic acid complex).
Best grade D across 8 graded outcomes Other Last checked
The short answer
From 10 sourcesPhosphatidic acid is a signalling lipid marketed for muscle growth because it activates mTOR in cells. Five small trials in resistance-trained men gave mixed results: one 28-man trial found more lean mass and strength, others found no clear difference from placebo, and a 2022 scoping review concluded the evidence does not support it for muscle or performance.
Every graded outcome on this page
8 rows · line = participants- DGrade DCortisol and distress during a lab stress test (PS-PA complex)Stressn 80
- DGrade DPremenstrual symptoms (PS-PA complex)PMSn 40
- DGrade DLean mass, muscle size and strength with resistance trainingMusclen 28
- DGrade DBody composition and leg strength at 250 or 375 mg/dayMusclen 28
- DGrade DLean mass and strength with a PA-based blendMusclen 18
- DGrade DLean mass and squat strength with resistance trainingMusclen 16
- DGrade DMuscle protein synthesis after resistance exercise in older menMusclen 16
- DGrade DMuscle thickness and 1RM strength with resistance trainingMusclen 15
- 5 more graded outcomes, in the evidence chapter
Key facts
- What it is
- A phospholipid that acts as a signalling molecule; the stress studies used a soy-lecithin form17
- Usual studied dose
- 750 mg/day with resistance training for 8 weeks; one trial tested 250 and 375 mg/day1243
- Best positive trial
- 28 trained men: +2.4 kg lean mass and +51.9 kg leg press versus placebo after 8 weeks at 750 mg/day1
- Null trial
- 15 trained men at 750 mg/day: no difference from placebo in muscle thickness or 1RM strength4
- Older men
- In 16 older men, a single 750 mg dose after exercise blunted the rise in muscle protein synthesis seen with placebo9
- Review verdict
- A 2022 scoping review of 6 studies found the evidence does not support phosphatidic acid for performance or body composition6
What it is
Phosphatidic acid is a membrane phospholipid and signalling lipid sold as a muscle-building supplement.
How it works
ProposedPhosphatidic acid binds and activates mTOR, the cell's main growth switch for muscle protein synthesis. In muscle cells, soy phosphatidic acid stimulated mTOR signalling more than egg-derived PA. Whether oral doses raise mTOR signalling in human muscle enough to add muscle beyond training is unproven.16
Forms, side by side
2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.
Phosphatidic Acid forms compared
2 forms| 2 forms | (sports supplements) | Phosphatidylserine-phosphatidic acid complex (PAS) |
|---|---|---|
| Absorption in people | No human absorption data are cited; in muscle cells soy PA stimulated mTOR more than egg PA.1 | No head-to-head human data.7 |
| GI tolerance | The training-trial abstracts do not report adverse events.14 | The PMS trial authors judged 400 mg PS + 400 mg PA per day safe over 3 cycles.8 |
| Studied for | Muscle and strength with resistance training (250–750 mg/day) | Stress reactivity and premenstrual symptoms |
- Phosphatidic acid (sports supplements)
- Absorption in people
- No human absorption data are cited; in muscle cells soy PA stimulated mTOR more than egg PA.1
- Studied for
- Muscle and strength with resistance training (250–750 mg/day)
- Phosphatidylserine-phosphatidic acid complex (PAS)
What the human research says
Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.
Trial map
8 graded outcomes, largest study first8 graded outcomes: 3 improved, 3 mixed, 1 no effect, 1 worsened. The largest, a 2004 randomized trial of 80 people on cortisol and distress during a lab stress test (PS-PA complex), found mixed results. One outcome found a worsening: muscle protein synthesis after resistance exercise in older men (16 people).
1Cortisol and distress during a lab stress test (PS-PA complex)
Mixed · Grade D · RCT, 80 people, 2004
Healthy adults (four groups of 20)
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Cortisol and distress during a lab stress test (PS-PA complex) | Mixed | 80 | Grade D · RCT, 2004 | Healthy adults (four groups of 20) |
| Premenstrual symptoms (PS-PA complex) | Improved | 40 | Grade D · RCT, 2018 | Women aged 18–45 with premenstrual syndrome (Germany) |
| Body composition and leg strength at 250 or 375 mg/day | Mixed | 28 | Grade D · RCT, 2016 | Resistance-trained men |
| Lean mass, muscle size and strength with resistance training | Improved | 28 | Grade D · RCT, 2014 | Resistance-trained men, mean age 21 |
| Lean mass and strength with a PA-based blend | Improved | 18 | Grade D · RCT, 2016 | Strength-trained men on a monitored diet |
| Muscle protein synthesis after resistance exercise in older men | Worsened | 16 | Grade D · RCT, 2019 | Older men doing one-leg resistance exercise |
| Lean mass and squat strength with resistance training | Mixed | 16 | Grade D · Pilot RCT, 2012 | Resistance-trained men |
| Muscle thickness and 1RM strength with resistance training | No effect | 15 | Grade D · RCT, 2017 | Resistance-trained men, mean age 23 |
Every graded row
8 rowsShowing 8 of 8 outcomes. Human trials only.
DGrade DCortisol and distress during a lab stress test (PS-PA complex)StressMixedRCT
n 80 · 2004
Mixed 400 mg/day blunted ACTH and cortisol responses and distress during the Trier Social Stress Test; 600 and 800 mg/day did not.
- Design
- RCT, n = 80, 2004
- Population
- Healthy adults (four groups of 20)
- Form
- Soy lecithin phosphatidic acid and phosphatidylserine complex (PAS)
- Dose
- 400, 600 or 800 mg/day
- Duration
- 3 weeks
- Source
- Reference 7 · PubMed 15512856 (opens PubMed)
DGrade DPremenstrual symptoms (PS-PA complex)PMSImprovedRCT
n 40 · 2018
Improved Total premenstrual symptom scores (DRSP) improved more than with placebo (p=0.001), mainly physical symptoms; the number meeting PMS criteria did not differ.
- Design
- RCT, n = 40, 2018
- Population
- Women aged 18–45 with premenstrual syndrome (Germany)
- Form
- Lecithin phosphatidylserine and phosphatidic acid complex (PAS)
- Dose
- 400 mg PS + 400 mg PA per day
- Duration
- 3 menstrual cycles
- Source
- Reference 8 · PubMed 29576358 (opens PubMed)
DGrade DLean mass, muscle size and strength with resistance trainingMuscleImprovedRCT
n 28 · 2014
Improved Lean body mass (+2.4 kg), muscle cross-sectional area (+1.0 cm) and leg press strength (+51.9 kg) increased more than with placebo.
- Design
- RCT, n = 28, 2014
- Population
- Resistance-trained men, mean age 21
- Form
- Phosphatidic acid
- Dose
- 750 mg/day
- Duration
- 8 weeks of periodized training
- Source
- Reference 1 · PubMed 24959196 (opens PubMed)
DGrade DBody composition and leg strength at 250 or 375 mg/dayMuscleMixedRCT
n 28 · 2016
Mixed All groups gained lean mass, muscle size and strength with no significant group differences; magnitude-based inference rated PA as "likely" helpful for size and strength.
- Design
- RCT, n = 28, 2016
- Population
- Resistance-trained men
- Form
- Phosphatidic acid
- Dose
- 250 or 375 mg/day
- Duration
- 8 weeks of training
- Source
- Reference 3 · PubMed 27803633 (opens PubMed)
DGrade DLean mass and strength with a PA-based blendMuscleImprovedRCT
n 18 · 2016
Improved Lean mass and leg- and bench-press 1RM rose more than with placebo; fat mass, thigh muscle, jump, agility, power and push-ups did not differ.
- Design
- RCT, n = 18, 2016
- Population
- Strength-trained men on a monitored diet
- Form
- Blend: phosphatidic acid with leucine, HMB and vitamin D3 (MaxxTOR)
- Dose
- Daily blend (PA amount not stated in the abstract)
- Duration
- 8 weeks of training (3 days/week)
- Source
- Reference 5 · PubMed 27274715 (opens PubMed)
DGrade DLean mass and squat strength with resistance trainingMuscleMixedPilot RCT
n 16 · 2012
Mixed Lean mass rose 2.6% vs 0.1% and squat strength 12.7% vs 9.3%, but standard statistics showed no significant difference; magnitude-based inference rated the benefits "likely".
- Design
- Pilot RCT, n = 16, 2012
- Population
- Resistance-trained men
- Form
- Phosphatidic acid
- Dose
- 750 mg/day
- Duration
- 8 weeks of training (4 days/week)
- Source
- Reference 2 · PubMed 23035701 (opens PubMed)
DGrade DMuscle protein synthesis after resistance exercise in older menMuscleWorsenedRCT
n 16 · 2019
Worsened Exercise raised myofibrillar protein synthesis above rest with placebo but not with phosphatidic acid, and anabolic signalling (p70S6K, rpS6, 4E-BP1, Akt) was lower with phosphatidic acid.
- Design
- RCT, n = 16, 2019
- Population
- Older men doing one-leg resistance exercise
- Form
- Soy-derived phosphatidic acid vs rice-flour placebo
- Dose
- 750 mg single dose after exercise
- Duration
- Single session (5 hours of measurement)
- Source
- Reference 9 · PubMed 29970319 (opens PubMed)
DGrade DMuscle thickness and 1RM strength with resistance trainingMuscleNo effectRCT
n 15 · 2017
No effect Muscle thickness of four muscles and squat, deadlift and bench press 1RM improved in both groups with no difference between PA and placebo.
- Design
- RCT, n = 15, 2017
- Population
- Resistance-trained men, mean age 23
- Form
- Phosphatidic acid
- Dose
- 750 mg/day
- Duration
- 8 weeks of supervised training (3 days/week)
- Source
- Reference 4 · PubMed 28177725 (opens PubMed)
What the numbers add up to
Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.
Significance depended on the statistics
Small samples throughout
The stress effect was not dose-related
In the PS-PA stress trial only the lowest dose (400 mg) blunted cortisol; 600 and 800 mg did not.7
Studied doses
Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.
Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.
Doses studied in human trials
Interactions and safety
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
What Phosphatidic Acid meets
0 cited rows 5 tested togetherMedicines 0
No medicine rows in our sources.
Supplements and foods 4
- Tested together in a graded trial
Choose a medicine or supplement above to read its cited rows here.
Also cited: 5 tested together
HMBHMB page
Tested together
Lean mass and strength with a PA-based blend. Graded on the Phosphatidic Acid page; tested together is not a claim that they work better together.
L-LeucineL-Leucine page
Tested together
Lean mass and strength with a PA-based blend. Graded on the Phosphatidic Acid page; tested together is not a claim that they work better together.
PhosphatidylserinePhosphatidylserine page
Tested together
Cortisol and distress during a lab stress test (PS-PA complex). Graded on the Phosphatidic Acid page; tested together is not a claim that they work better together.
Tested together
Premenstrual symptoms (PS-PA complex). Graded on the Phosphatidic Acid page; tested together is not a claim that they work better together.
Vitamin D3 vs D2Vitamin D3 vs D2 page
Tested together
Lean mass and strength with a PA-based blend. Graded on the Phosphatidic Acid page; tested together is not a claim that they work better together.
Interactions
0 agentsNone found in our sources.
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between Phosphatidic Acid and your picks, and between your picks.
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Add a supplement or medicine you take to check it against Phosphatidic Acid.
Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.
Who should be careful
4 groups- Pregnancy and breastfeeding
- The cited trials give no safety data for pregnancy or breastfeeding, no LactMed or NCCIH monograph covers phosphatidic acid, and NCCIH notes that many supplements have not been tested in pregnant women or nursing mothers.1810
- Soy allergy
- The PAS complex is made from soy lecithin, and soy-derived PA was the form favoured in the muscle-cell work; the source should be on the label.71
- People on medicines
- We found no published drug-interaction studies or case reports for phosphatidic acid, so interaction data are limited; NCCIH notes that some supplements can harm people taking certain medicines.10
Reading the label, and the cost per dose
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
How to read the label
2 checksLabel dose vs studied dose
Have the bottle? Photograph its Supplement Facts panel and see each line, phosphatidic acid included, beside the doses and forms the trials used in Label X-Ray.
Cost per studied dose, without the sales pitch
Your numbers, no product dataEnter the price, servings and the amount per serving from your label.
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
7 answersDoes phosphatidic acid build muscle?
Does phosphatidic acid lower cortisol?
A PS-PA complex at 400 mg/day blunted cortisol in a lab stress test, but higher doses did not. Plain phosphatidic acid has not been tested for stress.7
Is phosphatidic acid safe?
How much phosphatidic acid was used in studies?
Does phosphatidic acid interact with medicines?
No interaction studies or case reports have been published, so the data are limited. NCCIH notes that some supplements can harm people taking certain prescription or over-the-counter medicines.10
Is phosphatidic acid the same as phosphatidylserine?
Sources
10 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
10 sources- 1Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy.RCT Nutr Metab (Lond), 2014 · PMID 24959196
- 2Efficacy of phosphatidic acid ingestion on lean body mass, muscle thickness and strength gains in resistance-trained men.Pilot RCT J Int Soc Sports Nutr, 2012 · PMID 23035701
- 3Eight Weeks of Phosphatidic Acid Supplementation in Conjunction with Resistance Training Does Not Differentially Affect Body Composition and Muscle Strength in Resistance-Trained Men.RCT J Sports Sci Med, 2016 · PMID 27803633
- 4Effects of phosphatidic acid supplementation on muscle thickness and strength in resistance-trained men.RCT Appl Physiol Nutr Metab, 2017 · PMID 28177725
- 5The effects of phosphatidic acid supplementation on strength, body composition, muscular endurance, power, agility, and vertical jump in resistance trained men.RCT J Int Soc Sports Nutr, 2016 · PMID 27274715
- 6The effects of phosphatidic acid on performance and body composition - a scoping review.Systematic review J Sports Sci, 2022 · PMID 34706625
- 7Effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) on the endocrine and psychological responses to mental stress.RCT Stress, 2004 · PMID 15512856
- 8A lecithin phosphatidylserine and phosphatidic acid complex (PAS) reduces symptoms of the premenstrual syndrome (PMS): Results of a randomized, placebo-controlled, double-blind clinical trial.RCT Clin Nutr ESPEN, 2018 · PMID 29576358
- 9The effect of acute oral phosphatidic acid ingestion on myofibrillar protein synthesis and intracellular signaling in older males.RCT Clin Nutr, 2019 · PMID 29970319
- 10Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
What changed
Every dated change to this page: what changed, who made it and why.
Change log
3 entries| Date | Change | Who and why |
|---|---|---|
| evidence, key facts, studied doses, who should be careful, FAQ | Searched PubMed for phosphatidic acid trials and reviews 2018–2026; no newer meta-analysis or training RCT found. Added a 2019 randomized single-dose trial in 16 older men (PMID 29970319; muscle protein synthesis blunted). Interactions checked: no published interaction studies, and no ODS, NCCIH, LactMed or LiverTox page covers phosphatidic acid; added a note on medicines and a pregnancy source (NCCIH Using Dietary Supplements Wisely). | Writer: Kymata Health EditorialTrigger: A–Z page audit |
| all | First draft. Every PMID checked against NCBI E-utilities esummary (title, journal and year taken from the record) and abstracts read for each cited row. | Writer: Kymata Health EditorialTrigger: new page |
| all | Adversarial review pass: every number in each evidence row's result, dose, duration, n and population fields was machine-checked against its PubMed abstract, and figures not in an abstract were confirmed in the PMC full text (noted per row). Unverified study-country, funding and mechanism wording was removed or sourced, rows whose sample size could not be confirmed were dropped, and retraction, erratum and expression-of-concern flags were checked on every PMID (two errata, noted on their rows; no retractions). Page set indexable. | Writer: Kymata Health EditorialTrigger: review |
Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.