# Silydianin

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/silydianin
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-19
**Evidence Score:** 6 / 10
**Category:** Compound
**Also Known As:** 2,3-Dehydrosilydianin, Silymarin D, Flavonolignan D, Milk thistle flavonolignan, Silybum compound D, Hepatoprotective flavonoid D

## Overview

Silydianin is a flavonolignan compound found in milk thistle that functions as part of the silymarin complex. It demonstrates antioxidant activity by reducing [reactive oxygen species](/ingredients/condition/antioxidant) production and shows potential [antiviral](/ingredients/condition/immune-support) properties.

## Health Benefits

• May support [liver health](/ingredients/condition/detox) as part of silymarin complex, though a 48-week RCT (n=78) showed no significant histological improvement in NASH patients (PMID:31536511)
• Demonstrates antioxidant properties by reducing [reactive oxygen species](/ingredients/condition/antioxidant) production in vitro studies
• Shows [antiviral](/ingredients/condition/immune-support) activity against enteroviruses including coxsackie B2, poliovirus, and EV71 with up to 100% inhibition at 400 µg/mL in cell studies
• May improve metabolic parameters in type 2 diabetes when taken as part of silymarin (200mg t.i.d. improved glucose and HbA1c, PMID:17072885)
• Could support gastric motility and metabolic syndrome management based on in vivo studies at 200mg/kg

## Mechanism of Action

Silydianin acts as an antioxidant by scavenging [reactive oxygen species](/ingredients/condition/antioxidant) and reducing oxidative stress in hepatocytes. The compound modulates cellular antioxidant enzyme systems and may interfere with viral replication through inhibition of viral RNA synthesis. It works synergistically with other silymarin components including silybin and silychristin to enhance [hepatoprotective](/ingredients/condition/detox) effects.

## Clinical Summary

Limited clinical research exists specifically on silydianin as an isolated compound. A 48-week randomized controlled trial (n=78) examining silymarin complex containing silydianin showed no significant histological improvement in NASH patients. Most evidence comes from in vitro studies demonstrating [antioxidant](/ingredients/condition/antioxidant) and [antiviral](/ingredients/condition/immune-support) activities. The clinical efficacy of silydianin alone remains poorly established compared to the broader silymarin complex.

## Nutritional Profile

Silydianin is a pure flavonolignan compound (C₂₅H₂₂O₁₀, molecular weight ~482.44 g/mol), not a food ingredient, and therefore carries no conventional macronutrient or micronutrient profile (zero protein, fat, carbohydrate, fiber, or caloric value in its isolated form). It is one of the minor constituents of silymarin, the standardized extract from milk thistle (Silybum marianum) seeds, typically comprising approximately 5–10% of the total silymarin complex by weight, compared to silybin which dominates at ~50–70%. As a bioactive compound, silydianin contains a phenylchromane skeleton with multiple hydroxyl groups conferring its [antioxidant](/ingredients/condition/antioxidant) capacity. Oral bioavailability of silydianin, like other flavonolignans, is generally low due to limited aqueous solubility, first-pass hepatic [metabolism](/ingredients/condition/weight-management), and poor intestinal absorption; studies on the broader silymarin complex suggest systemic bioavailability of individual flavonolignans typically falls below 1–5% from standard formulations, with phospholipid complexes (e.g., Siliphos) improving absorption by up to 4–5 fold. No standalone pharmacokinetic data specific to isolated silydianin in humans is currently published. In commercial milk thistle extracts standardized to 70–80% silymarin, silydianin concentration is estimated at roughly 35–80 mg per 1,000 mg extract. No dietary reference intakes (DRIs) or established daily values exist for silydianin.

## Dosage & Preparation

Clinically studied as part of silymarin extracts standardized to 70-80% flavolignans (silydianin comprises 10-20%). Doses range from 210mg/day (70mg t.i.d.) to 2100mg/day (700mg t.i.d.) for 8-48 weeks. Higher doses exceeding 1500mg/day have been confirmed safe. No isolated silydianin dosing data available. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Silydianin safety data is limited as it's typically consumed as part of milk thistle extracts rather than in isolation. General milk thistle safety profiles suggest mild gastrointestinal side effects may occur including nausea and diarrhea. Potential interactions with CYP450 enzymes may affect drug [metabolism](/ingredients/condition/weight-management), though specific silydianin interactions are not well-documented. Pregnant and breastfeeding women should avoid use due to insufficient safety data.

## Scientific Research

Clinical evidence primarily evaluates silymarin complex rather than isolated silydianin. A phase II RCT (PMID:31536511) testing silymarin in NASH patients found no significant histological improvement, while a meta-analysis (PMID:30477860) showed silymarin improved metabolic status in T2DM. A 4-month RCT (PMID:17072885) demonstrated improvements in fasting glucose and HbA1c with 600mg/day silymarin.

## Historical & Cultural Context

While no direct historical data exists on isolated silydianin, Silybum marianum (milk thistle) seeds have been used in traditional European herbal medicine for liver disorders since ancient times. The silymarin complex was popularized in the 20th century for [hepatoprotect](/ingredients/condition/detox)ion.

## Synergistic Combinations

Silybin, Silychristin, Alpha-lipoic acid, N-acetylcysteine, Vitamin E

## Frequently Asked Questions

### What is the difference between silydianin and silybin?

Silydianin and silybin are both flavonolignan compounds in milk thistle, but silybin is the most abundant and well-researched component comprising 50-70% of silymarin. Silydianin makes up a smaller percentage and has less clinical research supporting its individual effects.

### How much silydianin is in milk thistle extract?

Silydianin typically comprises 5-10% of standardized silymarin extracts from milk thistle. Most commercial milk thistle supplements contain 200-400mg of silymarin complex, providing approximately 10-40mg of silydianin per dose.

### Does silydianin work for fatty liver disease?

A 48-week clinical trial showed no significant histological improvement in NASH patients using silymarin complex containing silydianin. While in vitro studies suggest hepatoprotective potential, clinical evidence specifically for silydianin in fatty liver disease remains insufficient.

### Can silydianin be taken with other antioxidants?

No documented interactions exist between silydianin and common antioxidants like vitamin C or E. However, combining multiple antioxidants may have additive effects, so monitoring is advisable when using high doses of multiple antioxidant supplements.

### What foods naturally contain silydianin?

Silydianin is found naturally only in milk thistle seeds (Silybum marianum). It cannot be obtained from common dietary sources and requires milk thistle supplementation or consumption of milk thistle seed preparations to achieve therapeutic amounts.

### What does research show about silydianin's antiviral properties?

In vitro studies demonstrate that silydianin exhibits antiviral activity against several enteroviruses, including coxsackie B2, poliovirus, and enterovirus 71, with inhibition rates reaching up to 100% at concentrations of 400 µg/mL. However, these results are from laboratory studies and human clinical trials confirming antiviral efficacy in vivo are limited. The antiviral mechanism appears related to silydianin's ability to interfere with viral replication, though further research is needed to determine clinical relevance and optimal dosing for human use.

### Is silydianin safe for long-term supplementation?

Silydianin, as a component of the milk thistle silymarin complex, is generally recognized as safe with a long history of use in traditional medicine and clinical practice. A 48-week clinical trial involving NASH patients found silydianin-containing extract to be well-tolerated without significant adverse events reported. However, long-term safety data specific to isolated silydianin supplementation is limited, and individuals with liver disease or those taking medications should consult healthcare providers before extended use.

### How does silydianin's mechanism of action compare to other silymarin components?

Silydianin functions as an antioxidant by reducing reactive oxygen species production, a property it shares with other flavonolignans in silymarin like silybin, though research suggests varying potencies among components. While silybin is the most extensively studied silymarin constituent for liver protection, silydianin's antiviral properties appear more distinct and less characterized than those of other silymarin members. The synergistic effects of multiple silymarin components working together may provide broader benefits than any single compound alone, though direct comparative clinical studies are scarce.

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