Ursolic acid is a natural compound found in many plants, such as apples and rosemary. As a supplement, ursolic acid has many purported benefits, including weight loss and muscle building claims. Does science back up these claims? Read on to find out.
What is Ursolic Acid?
Ursolic acid is a natural chemical compound found in a wide variety of plants, such as rosemary and apples. It is said to have antioxidant, anti-inflammatory, and anti-cancer effects.
Ursolic acid belongs to a class of compounds called triterpenes, which are naturally produced in plants and animals. Triterpenes have a number of biological effects, which sometimes make them candidates for drug research .
- May help reduce fat
- May help build muscle
- May help in diabetes
- May reduce inflammation
- May have cancer-fighting potential
- Not well studied in humans
- Long-term safety unknown
- Poorly absorbed by the body
- May interact with medications
Sources Of Ursolic Acid
A wide variety of plants, fruits, and flowers contain varying amounts of ursolic acid. Certain parts of the plant (like the leaves, bark, and fruit skin) sometimes contain more ursolic acid [2, 3].
Some sources of ursolic acid include [2, 3]:
- Apple skin
- Marjoram leaves
- Rosemary leaves
- Oregano leaves
- Sage leaves
- Thyme leaves
- Lavender leaves and flowers
- Hawthorn leaves and flowers
- Eucalyptus leaves and bark
- Coffee leaves
Mechanism of Action
According to research, ursolic acid may have multiple effects in the body.
One key mechanism is ursolic acid’s ability to block cell signaling pathways. By blocking certain pathways, like MAPK/ERK and PI3K/AKT/mTOR, ursolic acid may alter how cells grow and replicate [4, 5, 6].
Ursolic acid may also able to inhibit certain transcription factors and enzymes. For example, some studies suggest ursolic acid blocks COX-2, an enzyme involved in inflammation, and NF-κB, a transcription factor that plays an important role in the immune response [7, 8].
Some other potential mechanisms include increasing the gene expression of bone cells, possible antibacterial properties, and promoting the activity of GLUT4, an important glucose transporter in the body [9, 10, 11].
Purported Health Benefits Of Ursolic Acid
The following purported benefits of ursolic acid are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of ursolic acid for any of the uses listed below. Remember to speak with a doctor before taking ursolic acid supplements. Ursolic acid should never be used as a replacement for approved medical therapies.
Insufficient Evidence For:
Preliminary studies looking at young adult men have found that ursolic acid may increase muscle strength and reduce lab markers that indicate muscle damage [12, 13].
According to one randomized, placebo-controlled clinical trial of 24 patients, ursolic acid may help reduce body weight, BMI, and waist circumference .
The previously mentioned clinical trial of 24 patients also found that ursolic acid may improve fasting glucose levels and insulin sensitivity .
Animal And Cell Research (Lacking Evidence)
No clinical evidence supports the use of ursolic acid for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
Ursolic acid has not been shown to treat or prevent cancer. The potential effect of ursolic acid in cancer has only been studied in animals and cells.
It’s important to note that many substances have anti-cancer effects in cells, including downright toxic chemicals like bleach. This doesn’t mean that they have any medical value. On the contrary, most substances (natural or synthetic) that are researched in cancer cells fail to pass further animal studies or clinical trials due to a lack of safety or efficacy.
With that in mind, researchers have investigated the effects of ursolic acid in animals and cells on the following types of cancer:
- Breast cancer [15, 16, 17, 18]
- Cervical cancer [19, 20, 21]
- Colon cancer [22, 23, 24, 25]
- Bladder cancer [26, 27, 28]
- Melanoma [29, 30, 31]
- Leukemia [32, 33, 34]
- Lung cancer [35, 36, 37]
- Liver cancer [38, 39]
- Gastric cancer [40, 41, 42, 43]
One study in rats suggests that ursolic acid may reduce high blood pressure by reducing heart rate and having a diuretic effect .
Several studies that artificially induced heart attacks in rats suggest that ursolic acid may help restore enzyme function and prevent DNA damage [45, 46, 47].
However, there is also evidence that ursolic acid may be detrimental to the cardiovascular system. An animal study found that ursolic acid may promote plaque formation in the blood vessels. In addition, a different animal study suggests that ursolic acid may make blood platelets become stickier and more likely to form clumps [48, 49].
A cell study found that ursolic acid may stimulate the growth of osteoblasts, a special type of cell that plays a role in bone formation .
A different study in mice shows that ursolic acid blocks the growth of osteoclasts, a special type of cell that helps break down bone tissue .
Ursolic acid may be able to block factors involved in inflammation, such as NFkB, TNF-alpha, and IL-1 beta [51, 52].
According to animal studies, ursolic acid may help reduce inflammation in specific organs, such as the brain and liver [52, 53, 54].
Interestingly enough, one study in mice compared topical ursolic acid with indomethacin, an NSAID drug. The researchers suggest that ursolic acid may be more effective at reducing inflammation than indomethacin. However, there are no human studies that look at ursolic acid and inflammation .
Preliminary research using cell models suggest that ursolic acid may have antibacterial activity against over a dozen different strains of common bacteria [56, 57, 58].
One animal study found that ursolic acid may improve survival and may reduce lung injury in rats with severe infection .
Several animal studies have examined the effects of ursolic acid after artificially inducing brain injury in mice. The results suggest that ursolic acid may help protect mouse brain cells from damage after brain injury [60, 61, 62, 63, 64, 65].
In a study looking at rats, researchers found that ursolic acid may increase antioxidant levels and decrease lab markers associated with liver injury in response to alcohol .
Other animal studies suggest that ursolic acid may reduce fat accumulation in the liver [67, 68].
Research in mice and pigs suggests that ursolic acid may also help regenerate the liver and improve liver transplantation in animals [69, 70].
A couple of mice studies suggest that ursolic acid may reduce anxiety when it comes to performing animal behavioral tests [71, 72].
Mice studies suggest that ursolic acid may have antidepressant-like effects according to animal behavioral tests that evaluate depression [73, 74].
Limitations and Caveats
A huge limitation of ursolic acid is the lack of human studies. In addition, the quality of existing human research is limited.
This is especially important for cancer research. Cell and animal studies have revealed some positive results, but it’s unknown if these effects translate to humans without further studies.
Side Effects & Precautions
There is currently insufficient evidence to determine the safety of ursolic acid. While phase I safety studies suggest that side effects are tolerable, the long term safety of ursolic acid is unclear.
Three small safety studies have evaluated the safety of ursolic acid in patients with advanced solid tumors and healthy adults. According to the researchers, ursolic acid was tolerable and most side effects ranged from mild to moderate [75, 76, 77].
It’s important to note that these studies only evaluated the safety of ursolic acid. There’s no evidence that ursolic acid is effective for cancer treatment in humans.
Some of the common side effects found in these safety studies are listed below. However, this list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects [76, 75]:
- Abdominal swelling
- Trace amounts of blood in the urine
- Elevated sodium levels
- Skin rash
Researchers found that diarrhea and liver damage are the two most common dose-limiting toxicities .
On the other hand, animal and cell studies also suggest that ursolic acid may promote plaque formation in the arteries, which may be dangerous for those at risk for cardiovascular disease [49, 48].
If you decide to take ursolic acid (or any other supplement) let your doctor know as there may be unexpected and potentially dangerous interactions with your other medications or health conditions. The drug interactions of ursolic acid are not well researched and the following items do not represent all potential interactions.
One study found that ursolic acid may block a cell transporter called OATP1B1. Some drugs require OATP1B1 to move them from the portal circulation into the liver to be metabolized. By blocking this transporter, ursolic acid may increase the amount of and effects of certain drugs, including [78, 79]:
- Statins (a class of cholesterol-lowering drugs)
A cell study shows that ursolic acid also blocks an enzyme called UGT1A4. This enzyme metabolizes a variety of substances in the body. Most importantly, this enzyme metabolizes lamotrigine, a common anti-seizure medication. This means an interaction between lamotrigine and ursolic acid may exist [80, 81, 82].
In the following sections, we’ll discuss the common forms and dosages of ursolic acid supplements that are commercially available. Ursolic acid supplements have not been approved by the FDA for medical use. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Ursolic acid supplements are usually in capsule form with strengths that range from about 100 mg to 250 mg. Alternatively, it can be purchased as a powder.
Certain plant extract supplements can also contain ursolic acid.
For instance, rosemary extract supplements can contain different percentages of ursolic acid. Often these products will advertise the concentration, such as 90% ursolic acid.
Another example is holy basil supplements. Popular products typically include 2.5% ursolic acid.
There is currently insufficient evidence to determine what a safe and effective dose of ursolic acid is.
Ursolic acid supplement manufacturers typically recommend about 150 mg taken 3 times a day, for a total of 450 mg per day.
Ursolic acid research usually uses similar doses, ranging from 150 mg to 450 mg
Also be aware that ursolic acid has poor bioavailability, meaning very little is absorbed when ingested. In fact, researchers are exploring new strategies, such as using nanocrystals, to improve its bioavailability [83, 84].
Ursolic acid is a chemical compound found in many plants and fruits.
Research is finding that ursolic acid may be effective in many conditions, including:
- Bacterial infection
It may also protect the heart, liver, and brain. It can boost blood flow and relax blood vessels, which may improve your cardio performance and endurance. On the downside, some studies indicate it may clog arteries or damage cells.
Studies in humans are lacking, however.
Initial cancer studies suggest that it may be safe, but further research is required.
As a supplement, many use ursolic acid to help burn fat and improve energy, but the reviews on its effectiveness tend to be mixed.
Those looking for natural bodybuilding gains combine it with tomatidine, another promising muscle-building compound from tomatoes that’s even less researched than ursolic acid.