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Phosphatidic Acid: mTOR, Muscle Growth, and Strength

Kevin Kuhn, Classified Nutrition

When it comes to supplements that focus on increasing muscle size and strength, the underlying mechanism or mechanisms almost always relate to some aspect of stimulating mTOR (mammalian target of rapamycin).

It may not say that on the supplement packaging, but that is really what the supplement claims are after.  Why is this important?  Well, if you want to maximize the effects of a supplement, you have to know whether or not the claims actually match with sound science and what we know about physiology and biochemistry.  That means we have to know what mTOR is and does, and how it can be leveraged to better achieve your body composition and performance goals.

So, what is mTOR?

Simply put, mTOR is the specific protein kinase in mammals that mediates the body’s control of cellular growth by regulating muscle cell structure, cellular translation, transcription, ribosome biogenesis, the transport of nutrients, as well as cellular death (autophagy).  It is therefore the central controller of cellular growth.

Due to the role of mTOR in cellular change and adaptation, the goal of training and nutrition is to activate and maximize these performance-improving effects.  Training is a natural mTOR activator, so as long as you are engaging in a quality training program, step 1 is being addressed.  Step two deals with your nutrition, since mTOR is highly dependent on a few specific dietary requirements.  The first of these dietary requirements is a surplus of caloriesIf you don’t ingest enough calories, the body cannot afford to make any major changes to fitness and training.

The second requirement deals with ingesting adequate protein to deliver the necessary amino acids for growth and recovery processes.

The next dietary requirement deals with adequate lipids (fat) to maximize hormone production and function.  It is under the realm of appropriate fat intake that some supplements have come to gain attention.

Among these supplements is Phosphatidic Acid.

Phosphatidic Acid (PA) is a lipid messenger that has been shown to play a significant role in mTOR signaling, and may therefore have a profound role in maximizing training induced adaptations like strength, muscle growth, fitness, and athletic performance.

Phosphatidic Acid: mTOR, Muscle Growth, and Strength

The exact mechanism of how PA boosts mTOR is still unknown, but the some scientists have theorized it has to do with the molecular shape of PA, and how the unique structure of PA is able to “turn up the volume” on mTOR signaling and thus send the body’s cells a louder message to “grow!”

A few studies on PA supplementation have shown it to be a significant stimulator in this manner.  In a study published back in 2014 in the journal Nutrition and Metabolism, 28 resistance-trained subjects participated in an 8 week periodized training program and ingested either 750mg of PA or a placebo.  After the 8 weeks of training and supplementing, the group ingesting PA had significantly greater increases in lean body mass, muscle cross-sectional area (muscle size), as well as greater increases in leg-press strength when compared to the placebo group.

In another study, published in 2012 in the Journal of the International Society of Sports Nutrition, 16 subjects participated in an 8 week long, 4 days per week, resistance-training program and ingested either 750 mg of PA or placebo.  The results showed a 3.4% greater increase in squat strength compared to the placebo, as well as a 2.5% greater increase in lean body mass compared to the placebo.

It seems very clear that PA has serious benefits for individuals looking to maximize mTOR activation.  At this point, the research tends to show more benefit for PA increasing muscle tissue size over increasing maximal strength.  This does not mean that PA may not be beneficial to athletes training at or near their max effort, especially as it relates to maximal athletic efforts.

We don’t have enough data to derive a definitive position on the exact benefits of PA for athletes; however, there is more than enough data to show that PA increases mTOR signaling, and that maximizing mTOR signaling can have amazing effects on muscle repair, recovery, and growth.  It may be a few years before we see any research on PA and athletes, so you’ll have to be your own lab rat for now.  Try it for 8 weeks and see what happens.  My guess is that you’ll really like the results.


Hall MN. mTOR-what does it do?. Transplant Proc. 2008;40(10 Suppl):S5-8.

Hoffman JR, Stout JR, Williams DR, et al. Efficacy of phosphatidic acid ingestion on lean body mass, muscle thickness and strength gains in resistance-trained men. J Int Soc Sports Nutr. 2012;9(1):47.

Joy JM, Gundermann DM, Lowery RP, et al. Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy. Nutr Metab (Lond). 2014;11:29.

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  1. Any recommendations on where to get PA from?

  2. There isn’t a standout brand or product that I am aware of yet. I’d go with a brand that has a solid reputation and make sure the doseage is the same used in the research.

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