Perhaps the first study to make us take notice was published in 2011 in which researchers used a “connectivity map” to search for compounds with anti-catabolic properties. The map allowed them to test more than 1,300 compounds for their effects on genes involved with muscle atrophy. As you can guess, ursolic acid rose to the top as a relatively powerful inhibitor of genes associated with muscle atrophy. It was then tested in mice, which received an injection of ursolic acid and then were fasted for 24 hours. Sure enough, ursolic acid reduced the expression of two key genes responsible for muscle atrophy in vivo.
Then the researchers wondered, naturally, if ursolic acid can prevent muscle atrophy during catabolic stress (i.e., fasting), might it cause muscle hypertrophy with the catabolic stress removed? So they gave rats ursolic acid in their chow for five weeks and then compared muscle mass to a group who didn’t receive it. Sure enough, ursolic acid caused significant increases in muscle mass and strength in the mice that received it in their chow.
This study was followed a year later by another study in mice, and it was demonstrated that ursolic acid not only increased muscle mass but also increased what is called “brown fat” while decreasing overall fatness. Brown fat differs from white fat in that it is mainly used to generate heat in the body…brown fat cells are like little space heaters whereas white fat cells are used to store energy, not burn it. As a result, the mice receiving ursolic acid had less body fat, even on a high-fat diet.
Most recently, ursolic acid was shown to extend the anabolic response to a bout of resistance exercise. The mTORC1 is part of a signaling pathway critical to stimulating muscle growth. Ursolic acid was shown to extend the activity of this pathway beyond six hours, whereas with training alone the pathway had returned to baseline by that time. This effect is of particular interest to veteran lifters who struggle to make gains because of a shortened anabolic response to training.
We’ve just detailed the “potential” that this supplement has, but now we must acknowledge what is keeping ursolic acid from reaching its potential. The problem with ursolic acid as a dietary supplement is its poor bioavailability. It’s thought that only ~1% of a dose of ursolic acid is actually absorbed. Efforts are currently underway to improve its bioavailability. Possible solutions include using cyclodextrins and reducing its particles down to nano size. Unfortunately, neither of these technologies are currently available in dietary supplement form. For those in the know, there is a transdermal form—but the cost is arguably outrageous considering that the theoretical improvement in bioavailability is yet unproven. For now, the most affordable way to get a hefty daily dose of ursolic acid is probably as a bulk powder. If you can stand the taste (it’s bad) it can be added to protein drinks. Otherwise plan on taking as many as 18 capsules per day. Either way you decide, take it with a meal (the animal studies we spoke about had it incorporated into their food) in case this may enhance absorption. - FLEX