Tribulus is a plant emerging in the modern supplement arena after being valued by many civilizations in antiquity. It is hailed for treating and improving sexual function, kidney function, and has shown promise in the areas of lowering blood glucose, blood pressure, and fighting cancer cells.
What is Tribulus Terrestris?
Tribulus terrestris is an herbaceous plant belonging to the caltrop family (Zygophyllaceae). The reference to caltrops (which are spiky, human-made weapons) comes from the fruit that develops after the flower blooms. When the flower blooms, a fruit begins to form, which then falls apart into five spiky burs which resemble caltrops. Due to the sharp, spiky burs, Tribulus is considered a weed. It can easily puncture bicycle tires, earning it the name “puncture vine.” 
The origin of Tribulus' name is from the Greek word meaning “water chestnut.” It was later translated into the Latin word “tribulos,” which means caltrop. It soon became a name that was associated with the Tribulus plant in classical times. 
Tribulus was used in many countries as a traditional remedy, and it has many different names. The Chinese revere it in their Traditional Chinese Medicine philosophy, and call it Ci Ji Li, Bai Ji Li, or Ji Li. The Ayurvedic physicians in India call it Gokshura, Swadukantaka, Shuuadamshtra, Trikantaka, Chanadhruma, Vanashrungata, and Ikshugandhika in Sanskrit. In Hindi, it is known as Gokharu. Other names for Tribulus in India are Gokuri in the Benagali, Nerinci in Tamil, Kante gokaru in Marathi, and Palleru Kayalu in Telugu. 
What is the history of Tribulus Terrestris?
Tribulus terrestris has been a staple in many traditional, plant-based, folkloric medicinal philosophies all over the world. In the modern era, some athletes in the Olympics used Tribulus to enhance their performance in the 1990s. 
- Greece: The ancient Greeks used Tribulus as a mood enhancer and a diuretic. 
- China: Tribulus was included in the earliest known Chinese medicine publication: “Shen Nong Ben Cao Jing.” The fruits were used as a diuretic and to treat the kidneys. Other uses were as a cough expectorant and to treat eyesight problems. It was a popular remedy to relieve vertigo, headaches, itchy skin and blocked milk supply in mothers. 
- India: The fruits were used to treat infertility, low libido, impotence, and erectile dysfunction. The root and fruits were also used as a cardiotonic in Ayurvedic medicine. 
- Sudan: It was used as a treatment for inflammation of the kidneys, to relieve irritation of the mouth, and for general inflammation. 
- Pakistan: Tribulus was used as a diuretic and to increase excretion of uric acid via urine. 
- South Africa and Bulgaria: It was used to reduce swelling, treat digestive dysfunction, cardiovascular diseases, increase sperm production, and to treat eye disease. 
There are also reports of tribal South Africans who coat the seeds of Tribulus with the juice of poisonous berries to create lethal weapons. 
Common types of Tribulus Terrestris
Tribulus is a taprooted, flowering plant that is native to the Mediterranean region. It grows well in southern Europe and Asia, Africa, Australia, and New Zealand. It can also be found in Central, South, and North Americas, and it was introduced to California in the twentieth century. It spread from California north to British Columbia, Canada, and became so widespread that it is known as a noxious weed. Some states in America and South Australia also regard Tribulus as an invasive weed. 
Tribulus is often referred to as a “goathead” plant and can be a nuisance to local wildlife and livestock who often suffer injuries in their mouths from grazing. Even though many countries view Tribulus as a pesky weed, it is very hard to eradicate it through herbicidal or biological methods. A common biological intervention has been to introduce two species of weevils to the Tribulus plant to eat it. The seeds are viable for an average of seven years, making it difficult to find a long-term solution. 
Common varieties of Tribulus include:
- Tribulus terrestris var. terrestris
- Tribulus terrestris robustus
- Tribulus terrestris bicornutus
- Tribulus terrestris var. inermis 
What is Tribulus Terrestris made of?
The fruits contain flavonoids, flavonol glycosides, steroidal glycosides, steroidal saponins, furostanol saponins, furostanol glycosides, furosteroidal saponins, sapogenins, and alkaloids. 
There are 108 steroidal saponins found in Tribulus. These are a few of the steroidal saponins:
- Tigogenin-3-O-β -d-glc(1 → 4)-β -d-gal (A)
- Terrestrosin F
- Tigogenin-3-O-β -d-xyl-(1 → 2)-[β -d-xyl-(1 → 3)]-β -d-glc(1 → 4)-[α -l-rha(1 → 2)]-β -d-gal (C)
- Gitonin (B)
- Terrestrosin A and B
- Gitogenin-3-O-β -d-glc(1 → 4)-β -d-gal
- 25R,S-5α-spiro-2α,3β-dihydroxyl-3-O-β -d-glc-(1 → 4)-β -d-gal
- Terrestrosin E
- Hecogenin 
The flavonoids of Tribulus include:
- Tribuloside 
The alkaloids of Tribulus include:
- Tribulusamide C
- Tribulusin A
- Tribulusimide C
Other constituents include:
- Benzoic acid
- 2-methyl benzoic acid
- Vanillic acid
- Ferulic acid
- Succinic acid
- Palmitic acid monoglyceride
- Docosanoic acid
- Tribulus acid
- Amino acids: threonine and alanine
- Uracil nucleic acid
- Physcion 
What are the benefits of Tribulus terrestris?
Tribulus terrestris is a diuretic
This study in mice confirmed that Tribulus is a diuretic and has the potential to assist with passing urinary stones.
Tribulus terrestris is an aphrodisiac
Animal studies have confirmed that Tribulus is an aphrodisiac.
How does Tribulus work as an aphrodisiac?
Tribulus has aphrodisiac properties due to its constituent furostenol glycoside.
Tribulus terrestris treats female sexual dysfunction
Tribulus terrestris lowers blood sugar in diabetics
This study focused on women with type 2 diabetes and concluded that Tribulus lowers blood glucose levels.
Tribulus terrestris lowers cholesterol
This study on animals fed with high-cholesterol diet concluded that Tribulus can lower serum lipid levels and decrease cell damage due to hyperlipidemia (high cholesterol).
How does Tribulus work to lower cholesterol?
Tribulus was found to decrease serum cholesterol in mice due to its saponins.
Tribulus terrestris supports the cardiovascular system
How does Tribulus lower blood pressure?
Tribulus lowers blood pressure by inhibiting the ACE enzyme (angiotensin-converting enzyme). 
Tribulus terrestris may fight cancer cells
A study concluded that Tribulus can stop cancer cells from spreading and attack human liver cancer cells in-vitro.
How does Tribulus work to fight liver cancer cells?
Tribulus inhibits NF-kB signaling and represses proliferation of tumor cells.
An in-vitro chemical assay found that Tribulus inhibited breast cancer cells by altering the morphology of the cancer cells (cell size shrunk and the nuclei contracted).
How does Tribulus work to fight breast cancer cells?
The saponins were found to be the cause of cancer cell inhibition in this study.
An in-vitro study involving cells from human malignant melanoma, human oral epidermoid carcinoma, human ovary carcinoma cells, and human breast ductal carcinoma demonstrated that Tribulus effectively fights the cancer cells.
How does Tribulus work to fight melanoma, oral, ovary, and breast duct cancers?
The spirostanol-based saponins are effective at fighting these types of cancer cells. 
Tribulus terrestris has analgesic properties
This study found that Tribulus has analgesic effects in vitro and encourages future studies to produce a Tribulus-based analgesic drug.
Tribulus terrestris is antifungal
In-vitro studies have determined that Tribulus is anti-fungal against Candida albicans and Cryptococcus neoformans.
How does Tribulus work as an antifungal?
The spriostanol-based saponins are responsible for Tribulus' antifungal properties.
Tribulus terrestris for muscle strength is currently conflicted
Despite many claims that Tribulus can increase physical exercise performance, this clinical trial with 22 adult male rugby players found that Tribulus did not increase muscle strength better than a placebo.
Tribulus terrestris for male erectile dysfunction is currently conflicted
One clinical study showed that Tribulus improved erectile function in men with partial androgen deficiency, and another study found a significant improvement in ED in a randomized, double-blind placebo-controlled trial.
How does Tribulus work for erectile dysfunction?
In the study involving men with partial androgen deficiency, both total and free testosterone levels were significantly increased, and this was the main theory behind how Tribulus worked for male ED. 
However, when a metanalysis of the data available between 1968-2015 was conducted, researchers discovered that the effect of Tribulus on the androgen enhancing effects on testosterone was an outdated explanation. The new consensus is that the emerging evidence suggests there are mechanisms in the endothelium that are dependent on nitric oxide. This is believed to account for the aphrodisiac and erectile benefits seen with Tribulus. Continuing research is in progress.
How to Use Tribulus Terrestris
Tribulus is available in capsule forms.
Safety and Side Effects of Tribulus Terrestris
Side effects of Tribulus include gastrointestinal symptoms (abdominal cramps, nausea, vomiting, constipation, or diarrhea) and excitability, insomnia, and heavy or prolonged menstrual bleeding. Two cases of kidney toxicity (nephrotoxicity) after drinking large amounts of water containing Tribulus were reported. People who have eaten the Tribulus fruit (that is covered in spines) suffered from bronchial polyps and punctures of the lung in 2 cases because of the migration of the spines into the thorax. 
Tribulus can cause renal toxicity in ruminant animals. 
Tribulus interacts with some medications, herbs, and supplements. Its main interactions with medications, herbs, and supplements are related to its blood-glucose and blood-pressure effects, so it is recommended that you discontinue Tribulus at least two weeks before surgery. 
If you are taking ACE inhibitor drugs, such as Captopril (Capoten), Vasotec (enalapril), Prinivil/Zestril (lisinopril), Altace (ramipril), and others, a moderate interaction may occur due to
Tribulus' ability to inhibit the ACE enzyme as well as these medications. 
If you are taking anti-diabetes drugs, (insulin, Diabeta/Glynase PresTabs, Micronase (glyburide), Glucophage (metformin), Amaryl (glimepiride), Actos (pioglitazone), Avandia (rosiglitazone), and others) a moderate interaction may occur because Tribulus may also lower blood sugar and hypoglycemia may occur. 
If you are taking Lithium, a moderate interaction may occur because Tribulus may reduce urinary excretion due to its diuretic properties and may increase systemic levels of lithium, which may warrant the dose of lithium to be decreased. 
Herbs and supplements which may interact with Tribulus include:
Hypoglycemic herbs and supplements, such as Panax ginseng, alpha-lipoic acid, guar gum, chromium, Siberian ginseng, bitter melon, devil's claw, garlic, fenugreek, horse chestnut, and psyllium may enhance Tribulus' effect on lowering blood glucose and cause hypoglycemia. 
Blood-pressure lowering herbs and supplements (hypotensives), (coenzyme Q-10, Andrographis, fish oil, cat's claw, casein peptides, L-arginine, lyceum, theanine, stinging nettle, and others, may enhance the hypotensive effect of Tribulus and cause blood pressure to go to low. 
- “Tribulus Terrestris.” Wikipedia, en.wikipedia.org/wiki/Tribulus_terrestris.
- Yanala, Suresh Reddy, et al. “A Recent Phytochemical Review – Fruits of Tribulus Terrestris Linn .” Journal of Pharmaceutical Sciences and Research, vol. 8, no. 3, 2016, pp. 132–140., www.jpsr.pharmainfo.in/Documents/Volumes/vol8Issue03/jpsr08031601.pdf.
- “Tribulus terrestris.” Foods, Herbs & Supplements. https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=39
- Zhu, Wenyi et al. “A review of traditional pharmacological uses, phytochemistry, and pharmacological activities of Tribulus terrestris.” Chemistry Central journalvol. 11,1 60. 11 Jul. 2017, doi:10.1186/s13065-017-0289-x
- Roaiah, MF, et al. “Pilot Study on the Effect of Botanical Medicine (Tribulus Terrestris) on Serum Testosterone Level and Erectile Function in Aging Males With Partial Androgen Deficiency (PADAM).” J Sex Marital Ther., vol. 42, no. 4, 18 May 2016, pp. 297–301., doi:10.1080/0092623X.2015.1033579.