Ursolic acid is a natural compound found in various plants, categorized as a pentacyclic triterpenoid. It has gained scientific attention for its potential impact on metabolic health. While recognized in traditional medicine, its specific effects on the human body, particularly concerning weight management, are now being explored through modern research. Preliminary findings suggest it influences bodily processes related to energy expenditure and body composition.
Sources of Ursolic Acid
Ursolic acid is naturally present in several common dietary sources. Apple peels are a recognized source, containing notable concentrations. Other plant-based sources include herbs like rosemary, thyme, oregano, sage, and holy basil. Berries such as cranberries and blueberries, along with fruits like plums and prunes, also contain ursolic acid.
Beyond whole foods, ursolic acid is available in supplement form, often derived from rosemary leaf extract. While dietary intake is generally safe, food concentrations may be lower than those in scientific studies, leading some to consider supplementation for higher intakes.
How Ursolic Acid May Influence Metabolism
Ursolic acid is thought to influence metabolism through several biological mechanisms. It may increase skeletal muscle mass, a metabolically active tissue that burns more calories at rest. Research suggests ursolic acid can activate Akt activity in skeletal muscle, a pathway involved in muscle growth, and increase the expression of genes like hexokinase-II and IGF-I, which promote glucose utilization and muscle signaling.
The compound may also reduce fat accumulation. Studies indicate that ursolic acid can enhance the activity of brown adipose tissue (BAT), a type of fat that generates heat by burning calories, increasing overall energy expenditure. This effect on brown fat is linked to increased sympathetic nerve activity and the growth factor IGF-1. Additionally, ursolic acid has been observed to improve insulin sensitivity, helping the body process glucose more effectively and reducing the storage of excess sugar as fat. It also modulates adipocyte transcription factors and activates AMP-activated protein kinase (AMPK), further contributing to its metabolic effects.
Scientific Findings on Ursolic Acid and Weight Management
Scientific investigations into ursolic acid’s effects on weight management show mixed results, with a distinction between preclinical and human studies. In animal models, particularly mice fed a high-fat diet, ursolic acid has shown promising outcomes. It increased skeletal muscle mass, enhanced brown fat, and improved energy expenditure, leading to reduced obesity, better glucose tolerance, and less fatty liver disease. These animal studies suggest ursolic acid might reduce adiposity and improve glucose metabolism by increasing muscle Akt activity.
However, human trial findings are more limited and less conclusive. A review of human studies on ursolic acid’s impact on adiposity and muscle mass revealed inconsistent results. Some human studies showed improvements in glycemic control and a reduction in body mass index, while others reported no significant changes in adiposity or muscle mass. One study indicated increased muscle strength and reduced body fat when ursolic acid supplementation was combined with resistance exercise. The variability in human study outcomes is attributed to differences in dosages, sources, and treatment durations. Therefore, while preclinical data are encouraging, more extensive human research is needed to confirm ursolic acid’s efficacy for weight management.
Considerations for Supplementation
Individuals considering ursolic acid supplementation should approach it with caution. Ursolic acid is generally well-tolerated at typical dosages, but higher doses or prolonged use may lead to side effects. These can include nausea, upset stomach, fatigue, diarrhea, and potential liver stress with excessive intake.
Ursolic acid can interact with medications, particularly those processed by liver enzymes. These interactions could alter drug effectiveness or increase adverse reactions. Therefore, especially for individuals with existing health conditions or those taking other medications, consulting a healthcare professional before starting any new supplement is strongly recommended. This guidance helps ensure safety and determines if supplementation is appropriate.