Pregnenolone
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| CAS Number | 145-13-1 (live-verified; PubChem, EINECS 205-647-4) |
| Molecular Formula / MW | C21H32O2 / 316.48 g/mol |
| Chemical Class | C21 steroid — 3β-hydroxy-5-pregnen-20-one. The apex precursor of all steroid hormones |
| Biosynthesis | Made from cholesterol by CYP11A1 (side-chain cleavage) in mitochondria — the rate-limiting step of steroidogenesis |
| Downstream Products | Progesterone, DHEA, cortisol, aldosterone, testosterone, oestrogens; and the neurosteroids allopregnanolone and pregnenolone sulfate |
| ⚠ Regulatory Status | A hormone precursor / prohormone. Status varies sharply by market; restricted or prescription-controlled in many jurisdictions |
| Claim Strength (Overview) | Emerging — positive pilot RCTs in schizophrenia negative symptoms; limited human data overall |
| Buy from Herbuno | Pregnenolone Powder → |
Name origin: Pregnenolone is named from the pregnane steroid skeleton (C21) with the -en- and -ol- and -one suffixes describing its double bond, hydroxyl and ketone. Its systematic name, 3β-hydroxy-5-pregnen-20-one, and its synonym Δ5-pregnenolone, both locate it precisely. Its position in biology is unusual and should be stated plainly: pregnenolone sits at the very apex of steroidogenesis. It is synthesised from cholesterol by CYP11A1 in the mitochondrion — the rate-limiting step of the entire pathway — and every steroid hormone in the human body descends from it: progesterone, DHEA, cortisol, aldosterone, testosterone, the oestrogens. It is also the parent of the neurosteroids allopregnanolone and pregnenolone sulfate, which act directly on GABA-A and NMDA receptors in the brain. What this means commercially, and it is not a small thing: pregnenolone is a hormone precursor. Supplementing it is not analogous to supplementing a vitamin or a polyphenol. It is upstream of the entire endocrine cascade, and a buyer should be under no illusion that it is a benign botanical. Regulatory status varies sharply between markets and must be confirmed before purchase. Research trajectory: The most interesting human work is not endocrine at all but neuropsychiatric, treating pregnenolone as a neurosteroid rather than a hormone precursor.
Evidence for Pregnenolone Applications
The best human evidence is a proof-of-concept psychiatric trial, and it is genuinely interesting. Following a 2-week single-blind placebo lead-in, patients with schizophrenia or schizoaffective disorder on stable second-generation antipsychotics were randomized to adjunctive pregnenolone (fixed escalating doses to 500 mg/day) or placebo for 8 weeks; patients receiving pregnenolone demonstrated significantly greater improvement in SANS negative-symptom scores (mean change 10.38) compared with placebo (mean change 2.33), p=0.048 (Marx 2009). The rationale is mechanistically specific: pregnenolone sulfate positively modulates NMDA receptors and could thus address hypothesised NMDA hypofunction in schizophrenia. Note that p=0.048 in a pilot is a marginal result. Claim strength: Emerging.
The signal has been reproduced in further pilot work, though the whole literature remains small. Review of the emerging clinical evidence records that adjunctive pregnenolone significantly decreased negative symptoms in a pilot proof-of-concept randomized controlled trial, with post-treatment elevations in pregnenolone and allopregnanolone correlated with cognitive improvement; a further pilot RCT reported significant improvements in negative symptoms, verbal memory and attention, and a third reported decreased positive symptoms and extrapyramidal side effects alongside improved attention and working memory (Marx 2011). These are all pilot trials in a psychiatric population under medical supervision at 500 mg/day. That is not a consumer supplement context. Claim strength: Emerging.
The neurosteroid mechanism is the coherent part of the story and is worth stating carefully. Pregnenolone is converted in the brain to allopregnanolone, a potent positive allosteric modulator of GABA-A receptors, and to pregnenolone sulfate, which modulates NMDA and GABA-A receptors in the opposite direction. Pregnenolone itself has been shown to activate CLIP-170 and promote microtubule growth. Notably, clozapine — the most efficacious antipsychotic — elevates pregnenolone in rodent hippocampus, and pregnenolone levels are altered in post-mortem brain tissue from patients with schizophrenia. This is a real neurobiological thread, not a supplement-marketing construction. Claim strength: Moderate (mechanistic).
The claims made in the consumer market — memory, anti-ageing, energy, "hormone balance" — are considerably less supported than the psychiatric ones, which is an odd inversion worth naming. Rodent work found memory-enhancing effects of pregnenolone and its metabolites, and a 12-week randomized placebo-controlled trial of escalating doses to 400 mg daily in bipolar depression improved depressive symptoms and found pregnenolone safe and well tolerated. But there is no substantial human evidence for pregnenolone as a general cognitive enhancer, anti-ageing agent, or "hormone balancer" in healthy people, and marketing it as such runs far ahead of the data. Claim strength: Emerging.
The central caution follows directly from the biochemistry rather than from any observed harm. Because pregnenolone is upstream of every steroid hormone, supplementing it means introducing substrate at the apex of a cascade whose downstream partitioning is not controllable by the person taking it — the distribution among progesterone, DHEA, cortisol, testosterone and the oestrogens depends on individual enzyme expression, sex, age and tissue. This is the fundamental problem with all prohormone supplementation: the input is known and the output is not. That is a sufficient reason for caution independent of whether a specific harm has been documented. Claim strength: High (established endocrinology).
Dosage & Formulator Specification
Herbuno carries Pregnenolone Powder. Buyers must confirm the regulatory status of pregnenolone in their destination market before purchasing — it is a hormone precursor, its status varies sharply between jurisdictions, and it is restricted or controlled in a number of them. Herbuno will discuss regulatory scope at enquiry and will not support marketing that presents pregnenolone as a benign general-wellness supplement.
Human trial dosing has been substantially higher than typical consumer products: the schizophrenia trials escalated to 500 mg/day and the bipolar depression trial to 400 mg/day, both under medical supervision in patient populations over 8–12 weeks. Consumer products commonly supply 10–50 mg, a dose at which the psychiatric trial evidence simply does not apply — and a formulator should be clear about which proposition they are making rather than borrowing the credibility of trials conducted at ten to fifty times their serving. Because downstream partitioning is individual and uncontrollable, dose escalation is not a neutral act.
Analytical verification should specify pregnenolone by HPLC against a certified reference standard, with full stereochemical confirmation — this is a steroid, and steroid isomers and related substances are not equivalent. Related-substance profiling should quantify progesterone, DHEA, and other steroid impurities specifically, since these carry independent hormonal activity and their presence at even low levels is material. Residual solvent testing appropriate to the semi-synthetic route (pregnenolone is generally produced from diosgenin or from soy/yam sterols by chemical synthesis, not extracted directly from plants) should be documented, and the production route stated.
Pregnenolone was described as safe and well tolerated in the psychiatric trials at 400–500 mg/day over 8–12 weeks, with a milder side-effect profile than the antipsychotics it was compared against. The cautions are structural rather than incidental. It is a hormone precursor upstream of the entire steroid cascade, and the downstream partitioning among progesterone, DHEA, cortisol, testosterone and oestrogens is not controllable by the user — this alone warrants medical supervision and argues against casual consumer use. It should be avoided in pregnancy and breastfeeding, and in anyone with a hormone-sensitive condition, including hormone-sensitive cancers. It may interact with hormonal medication and with corticosteroids. It appears on sporting anti-doping prohibited lists as a prohormone. And the human evidence base — several pilot trials in psychiatric populations — does not support the general-wellness claims under which it is most often sold.
Frequently Asked Questions — Pregnenolone
What actually is pregnenolone?
The apex precursor of every steroid hormone in the body. It is made from cholesterol by CYP11A1 — the rate-limiting step of steroidogenesis — and progesterone, DHEA, cortisol, aldosterone, testosterone and the oestrogens all descend from it, along with the neurosteroids allopregnanolone and pregnenolone sulfate. It is a hormone precursor, not a botanical.
What is the best human evidence for it?
Psychiatric, oddly — not the wellness claims it is usually sold on. A proof-of-concept RCT found adjunctive pregnenolone at up to 500 mg/day significantly improved negative symptoms in schizophrenia (SANS change 10.38 vs 2.33, p=0.048), with further pilot trials reporting improvements in verbal memory and attention. Marginal results, small pilots, medically supervised patients.
Do consumer doses match the trial doses?
No, and this matters. The trials used 400-500 mg/day under medical supervision. Consumer products commonly supply 10-50 mg — ten to fifty times lower. The trial evidence simply does not apply at those doses, and borrowing its credibility for a 25 mg capsule is not legitimate.
Why is it risky if the trials found it well tolerated?
Because the problem is structural, not incidental. Supplementing at the apex of the steroid cascade means the input is known and the output is not — downstream partitioning among progesterone, DHEA, cortisol, testosterone and oestrogens depends on individual enzyme expression, sex, age and tissue, and is not controllable by the user. That is the fundamental problem with all prohormone supplementation.
Related compounds: Diosgenin, Steroidal Saponins, Melatonin, Guggulsterones
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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