Tribulus is an herb that has been used in various systems of traditional medicine for enhancing libido, fertility, and vitality. Although many take tribulus seeking a natural “testosterone boost,” this herb won’t actually alter testosterone levels in healthy men. Read on to discover what the science says about tribulus.
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].
For more about the active components and mechanism of action of tribulus, plus the side effects and potential risks of supplementation, check out this post.
Purported Benefits of Tribulus Terrestris
The benefits in this section will all refer to the most well-studied species, Tribulus Terrestris, as tribulus.
Possibly Effective For
1) Libido and Sexual Function
Hypoactive sexual desire disorder (HSDD) or sexual dysfunction is a condition that reduces a person’s 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 some doctors will consider supplements alongside lifestyle and psychological interventions. Some evidence suggests that tribulus is a potential supplement option for both sexes. More evidence supports its use in women with reduced sexual desire or other types of sexual dysfunction .
In two 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 lower doses of a tribulus extract (7.5 mg/day) for 4 weeks [7, 8, 9].
In two studies of 90 women with sexual dysfunction, taking 750 mg/day tribulus improved sexual function and libido. This suggests tribulus might be effective in both premenopausal and menopausal women [10, 11].
Interestingly, tribulus may also increase sexual function in men – mainly by increasing desire and helping men 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 [12, 13, 14].
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 .
Insufficient Evidence For
The following purported benefits are only supported by limited, low–quality clinical studies. There is insufficient evidence to support the use of tribulus for any of the below–listed uses.
Remember to speak with a doctor before taking tribulus supplements. Tribulus should never be used as a replacement for approved medical therapies.
2) 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 proper scientific studies are still lacking to support this use .
Initially, scientists uncovered that tribulus increases sperm production in rats. They also looked at its potential mechanism in a cell study to see how it might affect sperm quality and survival time [22, 23].
Two clinical studies examined its effects in men with infertility. In one low-quality Ayurvedic study, taking 12g/day of tribulus granules for 60 days improved sperm quality in 63 men with low sperm count. The exact content of these granules was not specified .
In another study of 65 men with infertility, supplementing with 250 mg/day of tribulus for 12 weeks increased sperm count and quality .
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% [12, 24, 10, 26].
Based on the evidence, it’s very hard to say whether tribulus boosts DHEA. Some scientists 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, this theory remains unproven. More research is needed .
4) Blood Pressure and Heart Rate
Tribulus is traditionally used for heart-related health problems. Proper clinical trials are lacking to determine the effects of tribulus on blood pressure and heart rate in humans.
In mice with high blood pressure, Tribulus reduced blood pressure. Scientists suspect it might act by decreasing the activity of angiotensin-converting enzyme (ACE). ACE is an enzyme that increases blood pressure by constricting blood vessels. Drugs commonly prescribed for high blood pressure (called ACE inhibitors) act on this pathway [28, 29].
Scientists are also investigating the effect of saponins from tribulus on heart cells exposed to harmful chemicals in dishes. They are looking to determine the impact of tribulus on antioxidant levels, oxidative stress, and blood clotting in rat hearts and cells deprived of oxygen [30, 31, 32, 33, 34].
5) Blood Sugar Levels
In a trial of 98 diabetic people, 1 g/day of tribulus for three months reduced fasting blood sugar and HbA1c, a long-term marker of blood sugar control. Multi-center, large-scale studies are needed to determine the effects of tribulus on blood sugar .
Tribulus reduced blood sugar levels in diabetic mice, but these findings can’t be extrapolated to humans. Scientists believe that saponins anmhnfrvxd cinnamic acid found in this herb block enzymes that digest starches and sugars, which might prevent blood sugar levels from spiking after a meal. Future research should also determine whether it increases insulin levels, which helps shuttle sugar from the blood and into the cells [36, 37, 38, 39].
Lacking Evidence (Animal and Cell Studies)
No clinical evidence supports the use of tribulus 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.
6) Kidney Stones
Kidney stones occur when calcium oxalate builds up and forms crystals, which bind to kidney cells and injure them. Scientists are investigating how extracts of tribulus fruit might reduce calcium oxalate from clumping and forming crystals in kidney cells. Some researchers suspect that tribulus increases the flushing of fluids with the urine, which may help clear kidney stones [40, 41].
Quercetin and kaempferol in tribulus are hypothesized to 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 to the kidneys [42, 43].
The combination of Tribulus and an Ayurvedic herb called Boerhaavia diffusa reduced the growth of kidney stones and improved kidney health in rats .
In a rat study, tribulus increased the release of minerals and fluids from the body similar to a diuretic drug (furosemide). However, this type of diuretic effect would theoretically only be beneficial in people with kidney stones or high blood pressure, while in healthy people it might trigger slight electrolyte imbalances .
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. Scientists posit that this plant might work by lowering damage to the joints and bones and decreasing levels of inflammatory molecules such as TNF-α and IL-6. This theory remains unproven [45, 46, 47].
Scientists are investigating the effects of tribulus on inflammatory and allergic skin reactions. An antioxidant found in its fruit – called rutin – suppresses an 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 [48, 49].
Other research teams claim its potential anti-inflammatory properties may go beyond “skin-deep.” In one study, tribulus reduced inflammation and tissue damage in mice with pancreas inflammation. It had similar effects in the colon in mice with inflammatory bowel disease [39, 50].
9) UVB Radiation
Scientists are exploring whether tribulus prevents the death of human skin cells exposed to UVB radiation by preventing the activity of the pro-inflammatory protein NF-κB and increasing the activity of DNA-repairing genes .
10) Greying Hair
Some researchers found that tribulus may increase the activity of melanocyte stimulating hormone (MSH) in hair follicles in the lab. MSH increases melanin levels, which gives hair a darker color. Animal and human trials need to determine whether it can prevent or reduce greying hair, based on this potential mechanism .
A couple of research groups aim to find out if tribulus is active against the following microbes in cell culture:
- Bacteria that cause cavities and tooth plaque (including Streptococcus mutans and Actinomyces viscosus) .
- Candida albicans and another small yeast that can cause respiratory problems in humans (Cryptococcus neoformans) .
Lastly, 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, but its impact on acetylcholine in humans is completely unknown .
Possibly Ineffective For
Athletic Performance and Muscle Mass
The evidence is mixed, especially when it comes to healthy men with normal testosterone levels and sexual function. Future studies should use standardized extracts, as the effects may also vary depending on the concentration and type of active compounds.
However, 450 mg/day of Tribulus did not affect lean mass in another 5-week study of 22 elite athletes .
Tribulus caused weight gain in rats by raising testosterone levels, but it failed to affect testosterone in humans. In one study of 65 men with poor semen quality, tribulus decreased body fat and increased lean mass [17, 24].
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 [63, 64, 65, 26, 14, 25, 12, 66].
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 [14, 13].
Dihydrotestosterone (DHT) is a more potent form of testosterone that gives men their characteristic facial and body hair growth. On the other hand, excessive DHT is also implicated in 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 [24, 67].
Tribulus given by an injection in the vein increased DHT levels by 31% in primates and by 32% in rabbits .
In a couple of clinical studies, the effect of tribulus appeared to be mixed. For example, two 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. However, the ingredients in this formulation were not specified [35, 27].
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. It is theoretically possible that this plant only affects raised levels in people at risk of heart disease, though much more research is needed .
In rabbits, tribulus decreased total, LDL, and HDL cholesterol, and triglycerides. Tribulus also protected blood vessels from damage caused by a cholesterol-rich diet in animals and decreased total and LDL cholesterol and triglycerides in rats and chickens. These effects have not been proven in humans [69, 70, 71, 72].
Limitations and Caveats
Although it looks to be promising for a couple of 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.
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.
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Tribulus terrestris is a herb with a long history of use that can help improve libido and sexual function. This herb is also under investigation for potential benefits to fertility, blood sugar levels, and the heart.
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.