Shilajit is a dark, tar-like resin that seeps from cracks in high-altitude rock, mainly in the Himalayas, and is used in Ayurveda as a rejuvenating tonic. It is made up mostly of humic substances, with fulvic acid usually described as its main active fraction, plus minerals, trace elements and other organic compounds. Human research on it is limited to a few small, short trials, and the main practical concern is purity, since raw or poorly processed material can carry heavy metals and other contaminants.
Shilajit has moved from Ayurvedic pharmacies into gym bags and social feeds, usually sold with bold promises about energy and hormones. That makes it worth separating what the substance is, what traditional texts say about it, and what controlled studies have shown, and treating purity as seriously as benefits.
What is shilajit?
Shilajit is a natural exudate, a sticky, pale-brown to blackish-brown resin that oozes from layers of rock at high altitude, especially in summer when warmer temperatures soften it. The best-known sources are the Himalayas between India and Nepal, along with the Hindu Kush, Tibet and Afghanistan. Similar material is gathered in Central Asia and Russia, including the Altai Mountains, where it is usually called mumijo, mumie or mumiyo. A form found in northern Chile is sometimes sold as Andean shilajit.
Researchers generally describe it as the product of plant matter decomposing in rock crevices over long periods through microbial action. A 2012 review by Carrasco-Gallardo and colleagues in the International Journal of Alzheimer's Disease describes it as formed "for centuries by the gradual decomposition of certain plants by the action of microorganisms." A 2025 review by Kamgar and colleagues in Critical Reviews in Analytical Chemistry notes that its exact origin is still debated.
What is shilajit made of?
Shilajit is made mostly of humic substances, the same family of compounds that forms when organic matter breaks down in soil. Scientists divide humic substances by how they dissolve in water: humins (insoluble), humic acid (soluble in alkaline conditions) and fulvic acid (soluble across the pH range, and smaller in molecular size).
Fulvic acid is usually reported as the main bioactive fraction. The Carrasco-Gallardo review puts humic substances, including fulvic acid, at around 60 to 80 percent of the active material. Alongside them, analyses have reported:
- dibenzo-alpha-pyrones, a class of small aromatic compounds that some researchers consider a second key constituent;
- minerals, with calcium, potassium and magnesium prominent in recent analyses;
- trace elements, which can include useful ones and unwanted ones;
- amino acids, fatty acids and plant-derived phenolic compounds.
The key word is "varies." The Kamgar review concluded that no comprehensive analysis has ever catalogued everything in it, and that composition differs from region to region; purification changes it again. Two jars labelled "shilajit" may not contain the same material, which is why marketing figures promising a fixed number of minerals deserve skepticism. For how older traditions used minerals more broadly, see minerals and metals in ancient wellness traditions.
Shilajit in Ayurveda: shilajatu and the rasayana tradition
In classical Ayurveda, shilajit is known as shilajatu and is classed as a rasayana, a rejuvenative substance meant to support strength and vitality over time. The two foundational Sanskrit medical compendia, the Charaka Samhita and the Sushruta Samhita, both discuss it. A 2010 review in the International Journal of Ayurveda Research (Meena and colleagues) notes that the Charaka Samhita likens it to "stones of metal like gold," while the Sushruta Samhita calls it "a gelatinous substance."
The popular gloss on the name, "conqueror of mountains and destroyer of weakness," is better read as a sign of how the tradition valued the substance than as a literal translation or a health claim.
Two points matter for modern readers. First, Ayurvedic practice calls for purifying the raw resin before use, and modern reviews agree that unpurified shilajit risks exposure to mycotoxins and heavy metals. Second, a long history of use is not the same as tested evidence. A 2011 review in the Journal of Ethnopharmacology by Wilson and colleagues found shilajit in twenty classical formulations, but concluded that it "lacks scientific evaluation and systematic documentation" and that several claimed properties had not stood up to critical assessment.
What do human studies on shilajit show?
Human studies on shilajit are few, small and short, and the two most cited trials tested the same commercially produced, purified extract. The evidence base therefore rests heavily on one manufacturer's material.
Laboratory and animal studies have reported antioxidant, cognitive and metabolic effects, but those findings have not been confirmed in well-designed human trials. A 2014 review by Sidney Stohs in Phytotherapy Research made the same point, noting that "relatively few well-controlled human studies" exist and calling for more research on standardised products.
The testosterone study
The study behind most of the testosterone marketing is Pandit and colleagues, "Clinical evaluation of purified Shilajit on testosterone levels in healthy volunteers," published online in Andrologia in 2015 and in print in 2016 (volume 48, pages 570 to 575). It was a randomised, double-blind, placebo-controlled trial in healthy men aged 45 to 55, who took 250 mg of a purified extract twice a day for 90 consecutive days.
Compared with placebo, the shilajit group showed statistically significant increases in total testosterone, free testosterone and DHEA-S, while the pituitary hormones LH and FSH were maintained. As later summarised by Keller and colleagues, total testosterone rose about 20 percent and free testosterone about 19 percent.
What it does not show matters as much. It is one small trial in middle-aged men, using an industry-produced extract, and it has not been replicated at scale. It says nothing about women or younger men, and it measured blood hormone levels, not outcomes such as strength, libido or fertility. Read fairly, it is an early signal for larger independent trials, not support for the general claim that shilajit "raises testosterone."
The strength and fatigue study
The second widely cited trial is Keller and colleagues, "The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels," in the Journal of the International Society of Sports Nutrition (February 2019, volume 16). Sixty-three recreationally active men, average age about 21, were randomised to 250 mg a day, 500 mg a day or placebo for eight weeks, 21 to a group.
The positive results came from a subgroup analysis. Among men in the upper half of the sample, those taking 500 mg a day kept more of their maximal strength after a fatiguing leg-extension protocol than the low-dose and placebo groups, and had lower serum hydroxyproline, a marker of collagen breakdown. The 250 mg dose did not differ from placebo. The study did not measure hormones, and subgroup findings need confirmation.
Is shilajit safe? Heavy metals, contamination and fakes
The main safety issue with shilajit is purity, not the resin itself. Because it is a raw natural material collected from rock, unprocessed or poorly processed shilajit can contain heavy metals such as lead, arsenic and mercury, as well as mycotoxins and fungal contamination. Adulterated and counterfeit products are also a recognised problem, since a dark, sticky resin is easy to imitate.
The wider Ayurvedic supplement market shows why this matters. In a study published in JAMA on 27 August 2008, Robert Saper and colleagues bought 193 Ayurvedic products online and tested them for toxic metals. About one in five, 20.7 percent, contained detectable lead, mercury or arsenic. The rate was 21.7 percent for US-manufactured products and 19.5 percent for Indian-manufactured ones, a difference that was not statistically significant. Among the metal-containing products, 75 percent claimed to follow Good Manufacturing Practices. The study covered Ayurvedic products broadly, not shilajit alone, but it shows that a label is not proof of purity.
How to approach shilajit if you are considering it
Anyone considering shilajit should start with a clinician, then judge products on independent testing rather than marketing:
- Talk to a clinician first. This matters most for anyone who is pregnant or breastfeeding, anyone with a medical condition, and anyone taking medication that affects blood sugar, blood pressure or hormones, since interactions are possible.
- Look for independent third-party testing. A certificate of analysis from an outside laboratory, covering heavy metals, microbial contamination and mycotoxins, is the minimum worth asking for.
- Be skeptical of fixed mineral counts and hormone promises. They go well beyond the two small trials described here.
How shilajit is regulated in the US
In the United States, shilajit is sold as a dietary supplement under the Dietary Supplement Health and Education Act of 1994 (DSHEA). It is not FDA-approved. Makers may use structure/function statements with the standard FDA disclaimer, but may not claim that a product diagnoses, treats, cures or prevents any disease, and quality varies by brand and batch.
Billy Carson's reading
4biddenknowledge has not published a Billy Carson episode, podcast or post devoted to shilajit, and this article does not attribute any view on it, or any endorsement, to him. What his wider work offers is a way of approaching a subject like this one.
The site's biohacking coverage takes an evidence-first approach: name the study, state its size and limits, and keep tradition and trial results in separate boxes. That framing is set out in the biohacking for beginners guide, and it is the standard this article applies to shilajit. The Ayurvedic history is real, the human trials are small but genuine, and the purity problem is documented. The site's look at the evolution of biohacking in biotechnology traces how the movement grew from self-experimentation.
Watch, read and go deeper
Everything the site publishes on supplements, food, fasting and the body is collected in the biohacking topic hub, the best place to compare shilajit with other popular practices. For another traditional remedy given the same evidence review, see sea moss explained, which covers species confusion and iodine risk. For a habit with a much deeper research base, the guide to intermittent fasting and autophagy explains the Nobel-recognised science and what trials have found.
Frequently asked questions
Is shilajit the same as mumijo?
Broadly, yes. Mumijo, mumie and mumiyo are the names used in Russia and Central Asia, including the Altai Mountains, for the same kind of rock exudate that is called shilajit in India and Nepal. Composition varies by region and processing.
Does shilajit increase testosterone?
One randomised trial, Pandit and colleagues in Andrologia (2016), found total testosterone about 20 percent and free testosterone about 19 percent higher than placebo after 90 days in healthy men aged 45 to 55. It was a single small study of one commercial extract and has not been replicated at scale, so it does not show that shilajit raises testosterone in general. It reported nothing on women, younger men or outcomes such as strength, libido or fertility.
What is fulvic acid?
Fulvic acid is a type of humic substance, the family of compounds formed when organic matter decomposes. It dissolves in water at any pH and has a smaller molecular size than humic acid. In shilajit it is usually described as the main bioactive fraction, though the evidence for its effects in people is still limited.
Can shilajit contain heavy metals?
Yes. Raw or poorly purified shilajit can contain lead, arsenic or mercury, as well as mycotoxins and other contaminants, and counterfeit products are a known problem. A 2008 JAMA study found detectable toxic metals in about a fifth of Ayurvedic products bought online. Independent third-party testing from an outside laboratory is the most useful safeguard.
Who should avoid shilajit?
Anyone who is pregnant or breastfeeding, has a medical condition, or takes medication for blood sugar, blood pressure or hormones should talk to a clinician before using it. Interactions have not been well studied, and the small trials to date enrolled only healthy men.
Sources and further reading
- Pandit S, Biswas S, Jana U, De RK, Mukhopadhyay SC, Biswas TK. "Clinical evaluation of purified Shilajit on testosterone levels in healthy volunteers." Andrologia 48 (2016): 570–575.
- Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. "The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels." Journal of the International Society of Sports Nutrition 16 (2019).
- Saper RB et al. "Lead, mercury, and arsenic in US- and Indian-manufactured Ayurvedic medicines sold via the Internet." JAMA 300 (2008): 915–923.
- Carrasco-Gallardo C, Guzmán L, Maccioni RB. "Shilajit: a natural phytocomplex with potential procognitive activity." International Journal of Alzheimer's Disease (2012).
- Stohs SJ. "Safety and efficacy of shilajit (mumie, moomiyo)." Phytotherapy Research 28 (2014): 475–479.
- Wilson E et al. "Review on shilajit used in traditional Indian medicine." Journal of Ethnopharmacology 136 (2011): 1–9.
- Kamgar E, Kaykhaii M, Zembrzuska J. "A Comprehensive Review on Shilajit: What We Know about Its Chemical Composition." Critical Reviews in Analytical Chemistry 55 (2025): 461–473.
Talk to a clinician before adding shilajit or any supplement to your routine, especially if you are pregnant or breastfeeding, have a medical condition, or take prescription medication. These statements have not been evaluated by the Food and Drug Administration. This content is for information only and is not medical advice.
