Benefits
Muscle strength gains with ursolic acid during resistance training
In 16 trained men on a lifting program, 450 mg/day for 8 weeks raised knee strength more than placebo, without a gain in lean body mass. In 26 postmenopausal women, 450 mg/day raised handgrip strength more than placebo as a secondary outcome, while the main outcome, waist size, did not differ. Both trials were small, and other trials found no strength gain.
Muscle mass and strength across the other controlled trials
A 12-week trial of a loquat leaf extract (about 51 mg/day ursolic acid) in 54 healthy adults found no difference from placebo in knee extension torque, its main outcome, or in grip, muscle mass or physical function. An 8-week trial of 400 mg/day in 22 active men on a high-protein diet found no added gain in strength or muscle mass, and pooled data from six trials showed no change in lean body mass.
Blood inflammation markers (CRP, IL-6, TNF-α) during resistance training
In 22 low-activity men doing high-intensity lifting for 8 weeks, ursolic acid lowered CRP, IL-6 and TNF-α compared with placebo, and in 25 women aged 50 to 70 it lowered IL-6 more than placebo. A trial in 27 healthy men at 400 mg/day found no change in TNF-α, IL-6 or IL-10. These are blood markers from small trials, not outcomes people feel.
Fasting insulin and HOMA-IR during a resistance circuit program
In 25 women aged 50 to 70 with obesity, ursolic acid taken with an 8-week resistance circuit program lowered insulin and HOMA-IR, an index of insulin resistance, more than placebo did. Pooled data from six trials found no change in fasting glucose or insulin, and a trial in 26 postmenopausal women found no difference in fasting blood markers.
Body weight, waist size and body fat in human trials
Pooled data from six trials at 50 to 450 mg/day found no change in body weight, BMI, waist circumference or body fat percentage versus control. In 16 trained men, 450 mg/day lowered body fat percentage more than placebo, but a second trial from the same lab found no significant change. A 12-week trial at 150 mg/day in 24 adults with metabolic syndrome reported changes only within its ursolic acid group.
Muscle growth and brown fat in mouse studies
In mice fed a high-fat diet, ursolic acid increased muscle mass, grip strength, brown fat and energy expenditure, and reduced weight gain, glucose intolerance and fatty liver. The university behind that work applied for patents and one author co-founded a company. In people, a single 3 g dose did not change muscle growth signaling, and trials have not shown these effects.
Blood markers of muscle damage during resistance training
In 16 trained men on a lifting program 6 days a week, 450 mg/day for 8 weeks lowered blood creatine kinase, CK-MB and LDH, enzymes released by stressed muscle, and their changes differed from men who trained without it. The comparison group took no placebo and the trial was small; these are lab markers, not measured soreness or recovery.
Mechanism of action
IGF-1, Akt and mTOR signaling (mouse muscle, not seen in a human test)
In mouse muscle, ursolic acid increased Akt activity and IGF-1 signaling, and a systematic review describes mTOR activation and lower MuRF-1, a gene tied to muscle breakdown. In 9 trained men, a single 3 g dose after leg exercise raised plasma ursolic acid but did not change IGF-1 receptor, Akt, mTOR or p70S6K in biopsy tissue compared with placebo.
Brown fat and energy expenditure (mouse)
In mice, ursolic acid increased brown fat and energy expenditure, and a systematic review links this to UCP1 and AMPK activity in fat cells. A brown fat response to oral ursolic acid has not been shown in people, and pooled human trials found no change in body fat percentage.
Irisin and IGF-1 (blood markers in small human trials)
Two small trials in men reported higher serum or plasma irisin when ursolic acid was taken during resistance training, and one also reported higher IGF-1. Irisin is a signaling protein released by working muscle (a myokine). These are blood markers; the trials that measured muscle mass found no added gain, so a link to a felt benefit is unproven.
NF-κB inhibition (cell studies)
In cultured cells, ursolic acid blocked activation of NF-κB, a switch for inflammatory genes, by inhibiting IκBα kinase and p65 phosphorylation, and lowered COX-2 expression. These are lab findings. In people, median serum ursolic acid after 300 mg/day by mouth was 2.7 ng/mL in one study, and two small trials disagree on whether blood inflammation markers fall.
Clinical trials
Randomized placebo-controlled trial in Korea: 450 mg/day ursolic acid from rosemary leaf extract (one 150 mg capsule after each meal; product from Labrada, Houston) or guar gum placebo for 8 weeks during a supervised program 6 days a week. Funded by Korean government research grants and an Inje University grant. Very small arms (7 and 9) with several strength and blood measures tested; glucose and insulin did not change in either group. (Bang et al. 2014, Korean J Physiol Pharmacol)
16 healthy Korean men with over 3 years of resistance training experience (mean age 29, mean BMI 27): 7 on placebo, 9 on ursolic acid.
Isokinetic knee extension and flexion strength in both legs rose more with ursolic acid than with placebo, with significant group by time interactions for all four measures. Serum IGF-1 and irisin and body fat percentage also changed more with ursolic acid than with placebo (group by time interactions). Lean body mass and body weight did not change in either group. Two later placebo-controlled trials with strength as a main outcome found no difference.
Randomized controlled trial in Korea from the same lab and training protocol as an earlier 16-man trial: 450 mg/day ursolic acid (one 150 mg capsule after each meal; product from Labrada, Houston) or no supplement for 8 weeks of training 6 days a week. The control group took no placebo and no blinding is described. Body weight, body fat percentage and lean body mass did not change significantly in either group. Funded by Korean government research grants; no conflicts declared. (Bang et al. 2017, Korean J Physiol Pharmacol)
16 healthy Korean men with at least 3 years of resistance training (mean age 33): 8 per group.
Creatine kinase, CK-MB, LDH and B-type natriuretic peptide fell within the ursolic acid group, and the changes in these markers and in cortisol and myoglobin differed from the training-only group (group by time interactions, p<0.05). These are blood markers of muscle damage; soreness and recovery were not measured.
Randomized, double-blind, placebo-controlled trial at Pusan National University Yangsan Hospital, Korea: 500 mg/day loquat leaf extract (two 250 mg capsules; 102 mg/g ursolic acid, about 51 mg/day) or identical placebo for 12 weeks, taken after breakfast and dinner. Funded by a Korean government R&D program for functional food materials; the capsule maker held the randomization codes. Registered as NCT02401113. (Cho et al. 2016, Evid Based Complement Alternat Med)
54 healthy adults aged 19 to 65 recruited at a hospital in Yangsan, Korea (27 per group; 24 and 22 completed). Despite randomization, the sex ratio differed between the groups (P = 0.004).
Leg extension peak torque on a dynamometer, the primary outcome, did not differ between groups at 4 or 12 weeks, and neither did handgrip readings, DXA limb tissue, gait speed, chair-rise time or fasting blood tests. Gait speed and chair-rise time improved in both groups alike. A sex-split reanalysis, prompted by the imbalance, found one difference favoring the extract in right handgrip change within one sex subgroup at 12 weeks (2.3 vs 0.62 kg, P = 0.047; at 4 weeks P = 0.431). The methods did not plan this comparison and no correction for multiple testing was made, so it does not show an effect. No adverse effects were reported with the extract.
Double-blind placebo-controlled trial in Brazil: 400 mg/day ursolic acid or placebo for 8 weeks; both groups ate about 1.6 g/kg/day protein and followed the same resistance training program. Registered RBR-76tbqs; the authors declared no conflicts of interest. (Lobo et al. 2021, Clin Nutr)
22 physically active young men (placebo n=12, ursolic acid n=10).
Scale weight, mass index, thigh girth and measured lean tissue rose in both groups, as did bench press and knee extension lifts, with no difference between the groups on any of these. The authors concluded that ursolic acid had no added effect over the diet and lifting program.
Double-blind randomized placebo-controlled trial in Brazil: 450 mg/day ursolic acid or placebo for 8 weeks with a combined exercise program twice a week (about 60 minutes, moderate intensity). Waist circumference was the primary outcome; blood pressure, fasting blood tests, body composition and physical function were secondary. Registered RBR-276rrt; the authors declared no conflicts of interest. (Cione et al. 2021, Clin Nutr ESPEN)
26 postmenopausal women (mean age 61) meeting NCEP ATP III criteria for a cluster of cardiometabolic risk factors; 13 per group.
The primary outcome, abdominal girth, did not differ between groups, and neither did blood pressure, fasting blood tests, fat and lean tissue measures or the other secondary measures except one: handgrip strength rose more with ursolic acid (mean difference 1.8 kgf, 95% CI 0.3 to 3.2). Remission under the NCEP ATP III criteria was 38.5% in both groups.
Pilot balanced, double-blind, placebo-controlled trial in Brazil: 400 mg/day ursolic acid or placebo for 8 weeks during resistance training; serum TNF-alpha, IL-6 and IL-10 measured before and after. (Lobo et al. 2022, Biomed Pharmacother)
27 healthy men on a supervised lifting program (placebo n=13, ursolic acid n=14).
Serum tumor necrosis factor alpha, interleukin 6 and interleukin 10 did not differ between the ursolic acid and placebo groups after 8 weeks.
Randomized placebo-controlled trial in Iran: ursolic acid or placebo, one capsule three times a day for 8 weeks (dose per capsule not given in the abstract), during high-intensity resistance training 3 times a week. Very small sample; a later trial at 400 mg/day found no change in TNF-alpha or IL-6. (Asghari et al. 2020, Cardiovasc Hematol Disord Drug Targets)
22 healthy low-activity men.
Plasma irisin rose and CRP, IL-6 and TNF-α fell in the ursolic acid group compared with the placebo group (p<0.05). These are blood markers only; no outcome people feel was reported.
Randomized placebo-controlled trial in Iran: ursolic acid or placebo, one capsule three times a day for 8 weeks (dose per capsule not given in the abstract), with moderate-to-high intensity resistance circuit training; the abstract also refers to a control group and gives no group sizes. Analyzed by repeated-measures ANOVA. (Asghari et al. 2021, Endocr Metab Immune Disord Drug Targets)
25 women aged 50 to 70 with obesity (body mass index 30 to under 40).
Insulin, HOMA-IR (an index of insulin resistance), IL-6 and IL-15 fell further, and BDNF rose further, in the ursolic acid group than in the placebo group (p<0.05). The sample was very small, and pooled data from six trials found no change in fasting insulin.
Randomized crossover study in the US: 3 g cellulose placebo, 3 g L-leucine or 3 g ursolic acid taken right after each of three lower-body resistance exercise sessions; blood drawn up to 6 hours and biopsies taken at 2 and 6 hours. Serum insulin (p = 0.98) and IGF-1 (p = 0.99) did not differ. (Church et al. 2016, J Am Coll Nutr)
9 lifting-trained men, each tested under all three conditions.
Plasma ursolic acid rose at 2 and 6 hours after the ursolic acid dose, but IGF-1 receptor, Akt, mTOR and p70S6K in biopsy tissue did not differ from placebo. Leucine, not ursolic acid, raised tissue IGF-1.