What is Tribulus Terrestris?
Tribulus (Tribulus terrestris) is a plant that grows in the Mediterranean and in subtropical and desert regions around the world including India, Vietnam, China, Spain, Mexico, and Bulgaria. This common weed is particularly well-adapted to warm, dry regions. It got its nicknames “puncture vine” and “devil’s thorn” from the spikes that cover its fruits [1, 2].
This plant has a long history of use in ancient medicine systems. As part of Indian and Chinese traditional medicine, the roots and the fruits of tribulus were considered remedies for numerous diseases and general health tonics. Its historical uses include boosting libido and fertility, flushing fluid buildup (edema), reducing kidney stones, and fighting urinary infections .
Today, tribulus is commonly marketed and supplemented for increasing testosterone, libido and strength. Tribulus supplements are very popular performance enhancers among bodybuilders. Others take tribulus for its heart-protective effects or to remedy sexual issues.
As the popularity of tribulus increased, so did the misconceptions and false information surrounding its use. For one, taking tribulus to boost testosterone will probably not work if your levels are normal. Tribulus may help with infertility and libido, but its active compounds have a testosterone-independent mechanism of action .
The saponins and flavonoids found in tribulus are mainly responsible for the major benefits and effects of the plant. Of these, the steroidal saponin protodioscin is the most important one. Extracts of tribulus are usually standardized to contain a certain percentage of saponins in the form of protodioscin [5, 1, 6].
- Alkaloids (harmane, nonharmane, tribulusterine)
- Phenolic amides (terrestrosides A and B)
- Phytosterols (β-sitosterol, stigmasterol)
- Organic acids (cinnamic acid, vanillic acid, Tribulus acid)
- Amino acids (alanine and threonine)
The saponin profile varies depending on where the plant is grown. For example, varieties in southeast Europe (e.g. Bulgaria and Greece) have over 30 times the amount of protodioscin than varieties in Western Asia [18+].
Mechanism of Action
The diverse mix of active compounds in tribulus help explain its apparently confusing effects. How can the same plant act as an aphrodisiac in some cases, and help fight cancer or reduce inflammation in others? The key lies in its active compounds and their concentration in different formulations.
- The steroidal saponin protodioscin is responsible for the libido-enhancing effects of this plant. It acts as an aphrodisiac to increase sexual activity and blood flow to the sexual organs (by boosting nitric oxide) [19, 20].
- Other saponins (terrestrosides A and B and terrestrosin D) have anti-cancer and anti-tumor properties [R, R, R, R].
- Different active compounds (such as tribulosin and tribulusamides) prevent programmed cell death in healthy cells exposed to stress and reduce inflammation [11, 12, 16, 13, 21+].
Health Benefits of Tribulus Terrestris
The benefits in this section will all refer to the most well-studied species, Tribulus Terrestris, as tribulus.
1) Enhances Libido and Sexual Function
Hypoactive sexual desire disorder (HSDD) is a condition that reduces your interest in sex. People who suffer from it have a lack of sexual fantasies and desire that causes distress and relationship issues. It affects up to 30% of women and 15% of men .
Many factors can affect HSDD, and supplements can be considered alongside lifestyle and psychological interventions. Tribulus is one promising supplement option, especially in women with reduced sexual desire or other types of sexual dysfunction .
In 2 trials of 76 women with reduced sexual desire, taking 750 mg/day tribulus for up to 4 months improved libido, orgasm, and satisfaction from sex. Another trial of 30 women found similar results using much lower doses of a tribulus extract (7.5 mg/day) for 4 weeks [28, 29, 30].
In two studies of 90 women with sexual dysfunction, taking 750 mg/day Tribulus found improved sexual function and libido. This suggests tribulus is equally effective in both premenopausal and menopausal women [20, 31].
Interestingly, tribulus may also increase sexual function in men – mainly by increasing desire and helping overcome erectile dysfunction (ED).
In a 12-week trial of 172 men with ED and reduced sexual desire, taking a higher dose of tribulus (1,500 mg/day) improved satisfaction from sex, orgasm, and libido. Two other studies of 100 men with ED found lower doses (750 mg/day) for 3 months equally improved sexual function [32, 33, 34].
However, in a trial of 30 men with ED, 800 mg/day of tribulus didn’t work better than placebo .
Despite its popular use as a male libido enhancer, stronger evidence supports the use of tribulus in women with reduced sexual desire. And although it does offer some sexual benefits to men, the findings are weaker and less conclusive .
2) Improves Fertility In Men
Infertility is a global problem that affects 8 – 12% of couples worldwide. Low sperm count and poor sperm quality (movement and shape) account for more than 90% of male infertility cases. Tribulus is traditionally used to combat infertility issues in men, although scientific studies have only recently shed some light on its potential .
Two clinical studies examined its effects in men with infertility. In one Ayurvedic study, taking 12g/day of tribulus granules for 60 days improved sperm quality in 63 men with low sperm count . In another study of 65 men with infertility, supplementing with 250 mg/day of tribulus for 12 weeks increased sperm count and quality .
However, 750 mg/day for 3 months didn’t improve sperm quality or count, nor did it affect testosterone and LH in a study of 30 men with infertility .
Although its effects on fertility in women have not been studied, tribulus appears to be effective at improving sperm count and quality in men.
3) Reduces Cholesterol Levels
In a couple of clinical studies, the effect of tribulus appears to be mixed. For example, 2 studies found a strong effect. In a trial of 98 women with diabetes, 1 g/day of tribulus for 3 months reduced total and LDL cholesterol levels. In another trial of 75 people, 3 g/day of an Ayurvedic tribulus formulation reduced total cholesterol levels by 10% over the course of four weeks [41, 42].
On the other hand, taking 750 mg/day of tribulus didn’t affect cholesterol levels in one 12-week trial of 180 people. However, the study included participants with normal cholesterol levels, while this plant may only be effective at lowering already raised levels in people at risk of heart disease .
The effects of tribulus were more pronounced in animal studies. It decreased total, LDL, and HDL cholesterol, and triglycerides in rabbits. Tribulus also protected blood vessels from damage caused by a cholesterol-rich diet. What’s more, it also decreased total and LDL cholesterol and triglycerides in rats and chickens [44, 45, 46, 47].
Tribulus has a cholesterol-lowering effect but higher doses may be necessary and it may only be effective in people with high levels.
4) Lowers Blood Pressure and Heart Rate
In mice with high blood pressure, Tribulus reduced blood pressure by decreasing the activity of angiotensin-converting enzyme (ACE). ACE is an enzyme that increases blood pressure by constricting blood vessels. Based on this study, tribulus acts very similar to drugs commonly prescribed for high blood pressure (called ACE inhibitors) [48, 49].
Animal studies suggest tribulus may have broader heart-protective effects. In cell studies, saponins from tribulus protected heart cells exposed to harmful chemicals. It also increased antioxidant levels and reduced oxidative stress and damage in rat hearts deprived of oxygen. This may explain the basis for its traditional use in people with heart disease [50, 51, 52].
One cell-based study posits that tribulus may reduce excessive blood clotting that clogs blood vessels in people with heart disease. The risk of harmful blood clots increases when platelets become too sticky and excessively clump together, while tribulus prevented platelet clumping [53, 54].
To sum it up, tribulus can protect heart cells from stress and may improve heart health by lowering blood pressure.
5) Reduces Blood Sugar Levels
Tribulus reduces blood sugar levels in diabetic mice. Saponins and cinnamic acid found in this herb block enzymes that digest starches and sugars. This prevents blood sugar levels from spiking after a meal. It also increases insulin levels, which helps shuttle sugar from the blood and into the cells [55, 56, 57, 58].
By preventing carbohydrates from being digested and absorbed, tribulus helps keep blood sugar levels stable, especially after meals.
Animal and Cell Studies
The following studies were conducted only on animals and/or cells.
6) Kidney Stones
Kidney stones occur when calcium oxalate build up and forms crystals, which bind to kidney cells and injure them. An extract of tribulus fruit prevented calcium oxalate from clumping and forming crystals in kidney cell studies, while also protecting the cells from oxalate damage. Additionally, tribulus increases the flushing of fluids with the urine, which may help clear kidney stones [59, 60, 60].
Quercetin and kaempferol in tribulus decrease the activity of the enzyme that forms oxalate (glycolate oxidase). In rats with kidney stones, tribulus reduced the growth of the stones and prevented damage the kidneys [61, 62].
The combination of Tribulus and an Ayurvedic herb called Boerhaavia diffusa reduced the growth of kidney stones and improved kidney health in rats .
Tribulus may also help flush kidney stones by acting as a diuretic. In a rat study, it increased the release of mineral and fluids from the body more than a strong diuretic drug (furosemide). However, this type of diuretic effect will only be beneficial in people with kidney stones or high blood pressure, while in healthy people it may trigger slight electrolyte imbalances .
Although more research is needed, the antioxidants in tribulus may help fight kidney stones and prevent kidney damage, while its diuretic action helps flush kidney stones.
7) Pain & Arthritis
In one rat study, Tribulus reduced pain due to physical injury to a similar degree as aspirin. It also reduced pain in rats with arthritis and osteoarthritis. This plant works by lowering damage to the joints and bones and decreasing levels of inflammatory molecules such as TNF-α and IL-6 [64, 65, 66].
Tribulus shows promise for soothing inflammatory and allergic skin reactions. An antioxidant found in its fruit – called rutin – suppresses the overactive immune response in the skin. Applying the fruit extract to the skin of mice reduced inflammation. It worked by preventing the activation of mast cells, immune cells that drive skin inflammation and cause redness [67, 68].
Its anti-inflammatory effects may go beyond “skin-deep”. In one study, tribulus reduced inflammation and tissue damage in mice with pancreas inflammation. What’s more, this plant also reduced inflammation and tissue damage in the colon in mice with inflammatory bowel disease. Whether tribulus could help people with IBS is still unknown [58, 21].
9) Damage from UVB Radiation
Creams and lotions made from tribulus roots may help protect the skin from UVB damage, but more research is needed.
10) Greying Hair
Tribulus increased the activity of melanocyte stimulating hormone (MSH) in hair follicles in mice. MSH increases melanin levels, which gives hair a darker color. These studies suggest tribulus may prevent or reduce greying hair, but animal and clinical studies would need to confirm it .
11) Stress and Depression
In a cell study, Tribulus stopped liver cancer growth and caused programmed cell death (apoptosis) in cancer cells. Another cell study found that saponins from Tribulus reduced the growth of breast cancer cells [72, 73].
Terrestrosin D, a steroidal saponin from tribulus, prevented the growth of prostate cancer cells and killed them. In mice, the same compound prevented the growth of new blood vessels that tumors need to grow, halting its spreading .
13) Bacteria and Fungi
In a cell study, tribulus prevented the growth of several species of bacteria that cause cavities and tooth plaque (including Streptococcus mutans and Actinomyces viscosus) .
Acetylcholinesterase is an enzyme that breaks down the neurotransmitter acetylcholine. This neurotransmitter orchestrates cholinergic activity in the body and is vital for memory, learning, alertness, and attention. Tribulus weakly-blocked the activity of acetylcholinesterase in a cell study, which suggests it may boost acetylcholine .
Insufficient or Conflicting Evidence
Although tribulus is often advertised for increasing testosterone levels, research does not support its effectiveness for this use.
Studies have found that tribulus increases testosterone levels in rats, mice, and primates. But the same line of research has not been fruitful in humans. On the contrary, tribulus did not increase testosterone levels (free or total) in multiple studies in men with either low or normal testosterone levels [19, 78, 79, 80, 34, 40, 32, 81].
In two studies of 100 older men with low testosterone, 750 mg/day of tribulus did significantly raise total and free testosterone levels. Both studies had the same authors and used people from an outpatient clinic at Cairo University. Their findings were never replicated [34, 33].
It’s unlikely that Tribulus increases testosterone levels in healthy men or women with normal sex hormone levels. More research is needed to confirm tribulus is able to increase testosterone in aging men with low levels.
Dehydroepiandrosterone (DHEA) is a weak anabolic (muscle-building) hormone made in the adrenal glands. The body uses DHEA to make sex hormones, testosterone or estrogen. It circulates in two forms: DHEA and DHEA sulfate (DHEAS). DHEAS is usually measured because it is found in much higher concentrations in the circulation.
In 245 men, 750 – 1,500 mg/day of tribulus didn’t change in DHEAS levels after 12 weeks. In 106 women, on the other hand, 750 mg/day increased DHEA levels over the course of 90 days. Lastly, in monkeys tribulus IV injections increased DHEAS levels by 29% [32, 39, 20, 80].
Based on the evidence, it’s very hard to say whether tribulus boosts DHEA. Some consider that its active steroid saponin, protodioscin, is converted to DHEA in the body. This theory suggests that tribulus may increase sex hormones indirectly, by raising DHEA. Although plausible, more research is needed .
Dihydrotestosterone (DHT) is a more potent form of testosterone gives men their characteristic facial and body hair growth. On the other hand, excessive DHT is also responsible for baldness in men.
Taking 750 mg of Tribulus increased DHT levels by 27% over the course of 12 weeks in a study of 65 men. However, another 10-week study of 15 men found no change in DHT levels after supplementing with 1,250 mg/day of Tribulus [39, 82].
Tribulus given by an injection in the vein increased DHT levels by 31% in primates and by 32% in rabbits .
Overall, larger clinical studies are needed to tease apart the effects of tribulus on DHT and the health implications.
Lean Muscle Mass
Tribulus caused weight gain in rats by raising testosterone levels. Testosterone is one of the best-known appetite and weight stimulants. In one study of 65 men with poor semen quality, tribulus decreased body fat and increased lean mass [23, 39].
However, 450 mg/day of Tribulus did not affect lean mass in another 5-week study of 22 elite athletes .
To sum it up, tribulus may have a weak muscle-building effect. But the evidence is mixed, especially when it comes to healthy men with normal testosterone levels and sexual function. The desired exercise enhancement may also strongly depend on the type of extract used and its active compounds.
Liver and Kidney Health
On one hand, some studies point to the liver- and kidney-protective benefits of tribulus. In mice, it lowered levels of a marker of liver damage (the enzyme ALT), reduced oxidative stress, and increased levels of the master antioxidant glutathione in the liver. Additionally, it could improve kidney function .
In another study in mice, tribulus protected the liver and kidneys from damage due to the toxic heavy metal cadmium. Its fruit also protects the livers and kidneys of mice exposed to mercury [85, 86, 87].
However, other studies suggest that tribulus may damage the liver and kidneys. In one study, Tribulus damaged the kidneys of rats. Goats that were fed high-dose tribulus experienced damaged liver and kidneys, while sheep fed 80% tribulus and 20% hay and wheat were left with similar damage (and increased liver enzymes) [88, 89, 90].
The most serious recorded case is of a man who drank 2 L of tribulus water had dangerously high AST and ALT levels. His kidneys started to suffer and he experienced seizures. The symptoms improved once he stopped taking tribulus. The exact dosage he was taking remains unknown. In another study, 750 mg/day of tribulus only mildly raised the liver enzyme AST (by 5%) [91, 34].
If you already have liver or kidney damage, it would be best to stay away from high-dose tribulus supplements and carefully monitor your liver enzymes and other markers of liver and kidney health.
Limitations and Caveats
Although it looks to be promising for various conditions, many of the benefits of Tribulus are yet to be confirmed by clinical trials.
Tribulus doesn’t increase testosterone in healthy men and its effectiveness in men with low testosterone needs to be confirmed.
Supplement Forms & Dosage
Although tribulus can be supplemented as powdered root or fruit, extracts are much more common. Extracts are usually standardized to contain 15-60% total saponins (~45% is typical) and at least 6% protodioscin [39+, 4+, 34+].
Tribulus varieties that grow in eastern Europe have much higher protodioscin (and much lower tribulosin) levels than those grown in India and Vietnam. If you’re seeking libido enhancement, protodioscin is the most important compound you should look for [92+].
Tribulus is sometimes combined with other herbs, such as:
- Boerhaavia diffusa in the supplement formulation Unex, used for kidney stones [63, 93].
- Sea oak kelp (Ecklonia bicyclis) and D-glucosamine, in a formulation called Tradamixina. This product is used for increasing libido and sexual function and improving urinary issues in men with benign prostate hyperplasia [94, 95].
Due to the lack of regulation in the supplement industry, it was discovered that some tribulus products were contaminated with anabolic steroids. As is usually the case, the banned steroids weren’t listed on the label. This may result in unintentional doping violations in athletes. The Australian Institute of Sport classifies tribulus as a substance with “high risk of contamination” that should not be used by athletes .
Side Effects & Precautions
Tribulus increased prostate specific antigen (PSA) levels by 20% in a study of 70 men who took 750 mg daily. PSA is higher in men with prostate cancer and other prostate disorders and is used by doctors to screen and monitor these conditions .
Ulcers are commonly caused by NSAIDs. In mice, Tribulus reduced pain to the same degree as the popular NSAID aspirin. Although it was not as harmful to the stomach as the NSAID, it still caused ulcers .
Blood Sugar-Lowering Drugs
Blood Pressure-Lowering and Heart Rate-Lowering Drugs
Tribulus can reduce blood pressure and heart rate. The combination of blood pressure- and heart-rate-lowering drugs may further lower blood pressure and heart rate .
Tribulus acts as a diuretic by increasing the amount of fluids and minerals the body releases in the urine. The combination of diuretics may further decrease fluid flushing and mineral balance .
Using 12g/day of an Ayurvedic tribulus fruit powder was effective for increasing fertility in men .
Users report that Tribulus increases libido, gives them a boost of energy, and provides a general feeling of well-being. Some users report headaches and increased irritability and aggression.
Buy Tribulus Terrestris
Tribulus terrestris is a herb with a long history of use that can help improve libido and sexual function. The active compounds responsible for its effects are steroidal saponins, plant compounds that may mimic the effects of sex hormones and increase blood flow. Of these, protodioscin is the most potent. Its levels vary depending on where the plants were grown: Southeastern Europe varieties have the highest levels and Asian varieties the lowest.
Besides boosting libido, this herb may help improve fertility, balance blood sugar levels, and protect the heart. Animal research points to its anti-inflammatory and cancer-fighting potential.
Although it is often touted to increase testosterone, research strongly suggests it has no such effect in healthy men. It may boost testosterone in men with low levels and in women, but the evidence is weak.
Professional athletes should be careful when supplementing with tribulus, as they run the risk of purchasing suspicious products contaminated with anabolic steroids.