# Stigmasterol

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/stigmasterol
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-19
**Evidence Score:** 2 / 10
**Category:** Compound
**Also Known As:** (3β,22E)-stigmasta-5,22-dien-3-ol, β-sitosterol homolog, 24-ethylcholesta-5,22-dien-3β-ol, stigmasta-5,22-dien-3β-ol, phytosterol, plant sterol

## Overview

Stigmasterol is a plant-derived phytosterol found in soybean oil, rapeseed, and various vegetables that competes with dietary cholesterol for intestinal absorption via the NPC1L1 transporter. Its primary mechanisms include modulation of sterol regulatory element-binding proteins (SREBPs) and inhibition of pro-[inflammatory](/ingredients/condition/inflammation) cyclooxygenase pathways.

## Health Benefits

• Anti-cholesterol effects shown in preclinical studies (evidence: preliminary)
• Antitumor activity via cell cycle arrest and apoptosis induction (evidence: in vitro/in silico)
• [Anti-inflammatory](/ingredients/condition/inflammation) properties demonstrated in laboratory settings (evidence: preliminary)
• Potential [neuroprotective effect](/ingredients/condition/cognitive)s (evidence: preclinical only)
• [Antioxidant activity](/ingredients/condition/antioxidant) observed in non-human studies (evidence: preliminary)

## Mechanism of Action

Stigmasterol reduces cholesterol absorption by competing with cholesterol at the Niemann-Pick C1-Like 1 (NPC1L1) transporter in intestinal enterocytes, downregulating SREBP-2-mediated cholesterol synthesis. It exerts [anti-inflammatory](/ingredients/condition/inflammation) effects by inhibiting NF-κB signaling and suppressing COX-2 and 5-LOX enzyme activity, reducing prostaglandin and leukotriene production. In cancer cell lines, stigmasterol induces G2/M cell cycle arrest and triggers intrinsic apoptosis via modulation of Bcl-2/Bax protein ratios and caspase-3 activation.

## Clinical Summary

The majority of evidence for stigmasterol derives from in vitro cell studies and rodent models, with limited randomized controlled human trials isolating its specific effects. Animal studies using doses of 50–200 mg/kg body weight have demonstrated reductions in total cholesterol and LDL-C by up to 30–40% in hypercholesterolemic rodent models. [Anti-inflammatory](/ingredients/condition/inflammation) effects have been quantified in murine models showing significant reductions in paw edema and TNF-α levels comparable to indomethacin at equivalent doses. Human evidence is largely extrapolated from broader phytosterol mixture trials, where 2 g/day of mixed plant sterols reduced LDL-C by 8–10%, making isolation of stigmasterol's specific contribution impossible at this stage.

## Nutritional Profile

Stigmasterol (C₂₉H₄₈O, MW 412.69 g/mol) is a plant sterol (phytosterol) and is not a macronutrient or food per se, but rather a bioactive lipophilic compound found embedded in the unsaponifiable fraction of plant-derived fats and oils. Key details: • Classification: Δ5,22-unsaturated phytosterol (3β-hydroxy-24-ethylcholesta-5,22-dien-3-ol); differs from β-sitosterol by the presence of a C-22 double bond. • Typical dietary intake: Estimated at 20–50 mg/day in Western diets as part of total phytosterol intake (~200–400 mg/day combined with β-sitosterol, campesterol, etc.); vegetarian/vegan diets may provide higher amounts (up to 60–80 mg/day of stigmasterol specifically). • Rich dietary sources and approximate concentrations: Soybean oil (~50–70 mg/100 g oil), rapeseed/canola oil (~3–10 mg/100 g), unrefined sunflower oil (~30–60 mg/100 g), calabar bean, fava beans (~15–30 mg/100 g dry weight), and various legumes, nuts, and seeds. Also present in some medicinal herbs and vegetables in lower concentrations (1–15 mg/100 g). • Macronutrient contribution: Negligible — stigmasterol is consumed in milligram quantities and contributes virtually no caloric energy, protein, carbohydrate, or dietary fiber. • Bioactive properties: Functions as a competitive inhibitor of intestinal cholesterol absorption via interaction with NPC1L1 transporter and displacement from mixed micelles; modulates membrane fluidity in cell membranes. • Bioavailability: Very low — intestinal absorption of stigmasterol is estimated at only ~0.5–5% (compared to ~40–60% for cholesterol), largely due to active efflux back into the intestinal lumen by ABCG5/ABCG8 sterol transporters. The C-22 unsaturation further reduces absorption relative to saturated-side-chain sterols like β-sitosterol (~5–10%). Absorbed stigmasterol is preferentially excreted in bile. • No vitamins or minerals are intrinsic to the stigmasterol molecule itself. • Solubility note: Highly lipophilic; poorly water-soluble. Bioavailability is enhanced when consumed with dietary fat or when formulated as stigmasterol esters (esterified with fatty acids), microencapsulated, or incorporated into lipid-based delivery systems (nanoemulsions increase apparent bioavailability by 2–4 fold in preclinical models). • Metabolites: Partially converted to stigmasterol glucuronide and other conjugates in the liver; does not serve as a precursor for human steroid hormones but is used industrially as a precursor for semi-synthesis of progesterone and corticosteroids.

## Dosage & Preparation

No clinically studied dosage ranges have been established for stigmasterol in humans. The compound is mentioned as a dietary supplement for cholesterol reduction in preclinical contexts, but without specific human dosing data or standardization percentages. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Stigmasterol is generally considered safe when consumed through dietary sources, but high-dose supplementation has not been rigorously evaluated in long-term human safety trials. Individuals with sitosterolemia, a rare autosomal recessive disorder causing excess phytosterol accumulation, must avoid phytosterol supplements including stigmasterol due to risk of accelerated atherosclerosis. Stigmasterol may potentiate the LDL-lowering effects of statins and ezetimibe, as both target overlapping cholesterol absorption pathways, warranting monitoring if combined. Pregnancy and breastfeeding safety has not been established in controlled studies, and supplemental doses are not recommended during these periods.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses were found in the research dossier. Current evidence is limited to preclinical data including in vitro, animal, and in silico modeling studies showing binding to receptors like ER-α, PR, HER2, and EGFR with affinities of -8.8 to -10 kcal/mol.

## Historical & Cultural Context

No traditional or historical medicinal uses were documented in the research. Current literature focuses exclusively on modern biochemical and pharmacological applications rather than ethnomedical history.

## Synergistic Combinations

Other phytosterols, omega-3 fatty acids, plant stanols, soluble fiber, coenzyme Q10

## Frequently Asked Questions

### What foods are highest in stigmasterol?

Stigmasterol is found in highest concentrations in soybean oil (approximately 55–70 mg per 100 g), rapeseed oil, and cocoa butter. Significant amounts are also present in legumes, green vegetables like spinach, and certain nuts. Dietary intake from whole foods is estimated at 20–50 mg per day in Western diets.

### Does stigmasterol lower cholesterol in humans?

Direct human clinical evidence specifically for stigmasterol is limited, as most trials test mixed phytosterol supplements containing sitosterol, campesterol, and stigmasterol together. Mixed phytosterol supplements at 2 g/day have consistently reduced LDL-C by 8–10% in meta-analyses of randomized trials, with stigmasterol contributing via NPC1L1-mediated competitive inhibition of cholesterol absorption. Isolated stigmasterol human trials are needed to confirm its individual contribution.

### Can stigmasterol help with inflammation?

Preclinical data supports anti-inflammatory activity, with stigmasterol inhibiting COX-2 and 5-LOX enzymes and suppressing NF-κB signaling in cell and animal models. A carrageenan-induced paw edema study in rats showed stigmasterol at 100 mg/kg produced inflammation reduction comparable to indomethacin. No human clinical trials have yet confirmed these effects at supplemental doses.

### Is stigmasterol safe to take as a supplement?

Stigmasterol is well tolerated in dietary amounts and is classified as GRAS (Generally Recognized as Safe) when consumed through food. Isolated high-dose supplementation lacks long-term human safety data, and individuals with sitosterolemia must strictly avoid it due to impaired phytosterol clearance via the ABCG5/G8 transporter system. Minor gastrointestinal side effects such as bloating have been reported with high-dose phytosterol supplements in general.

### What is the difference between stigmasterol and beta-sitosterol?

Stigmasterol and beta-sitosterol are both C29 phytosterols sharing a similar cholesterol-like core structure, but stigmasterol contains an additional double bond at the C22-C23 position in its side chain, making it structurally distinct. Beta-sitosterol has substantially more human clinical research behind it, particularly for benign prostatic hyperplasia and cholesterol lowering, while stigmasterol's research base remains largely preclinical. Both compete with cholesterol at intestinal NPC1L1 receptors, but their downstream receptor interactions and potency may differ.

### How does stigmasterol work to potentially protect nerve cells?

Stigmasterol may support neuroprotection through its antioxidant properties and ability to modulate cellular stress pathways, though current evidence is limited to preclinical laboratory studies in animal models and cultured cells. The proposed mechanisms involve reducing oxidative damage and supporting cell membrane integrity in neuronal tissue. Human clinical trials are needed to confirm whether these effects translate to meaningful neuroprotective benefits in living organisms. At present, stigmasterol should not be relied upon as a standalone treatment for neurological conditions.

### What is the current strength of scientific evidence for stigmasterol's health benefits?

The evidence for stigmasterol remains preliminary, with most research limited to in vitro (test tube) and in silico (computer modeling) studies, plus some preclinical animal models. While these studies suggest potential anti-cholesterol, anti-inflammatory, and antitumor mechanisms, human clinical trials are sparse and results are not yet conclusive. The antioxidant and neuroprotective effects are among the weakest supported, based primarily on non-human research. Consumers should view stigmasterol supplements as experimental, pending more robust human evidence.

### Does stigmasterol absorption differ when taken with food versus on an empty stomach?

As a plant sterol, stigmasterol is fat-soluble and absorption is likely enhanced when consumed alongside dietary fat, though specific bioavailability studies in humans are limited. Taking stigmasterol with a meal containing oils or fatty foods would theoretically maximize uptake compared to an empty stomach. Individual variation in digestive health and gut microbiota may also influence how effectively stigmasterol is absorbed and utilized. Standardized clinical guidance on optimal timing and food pairing for stigmasterol supplements is not yet established.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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