Milk Thistle (Silymarin) Quality and Labeling Standard
JHFC-S-009 Enacted: 3 September 2026 / Effective: the same day
Japan Certified Health Food Council (JHFC) — English translation of the standard. In case of discrepancy the Japanese text prevails. Japanese original
Japan Certified Health Food Council (JHFC)
Enacted: 3 September 2026 / Effective: the same day
Preamble (Rationale for Enactment)
The composition of milk thistle raw materials differs according to plant species, part used, and extraction method. "Silymarin" is not a single substance but the name of a fraction containing multiple flavonolignans and other constituents, and the interpretation of its total amount also varies with the measurement method. Fruit powder, extract, and silymarin amounts are not interchangeable. This Standard is established to provide a consistent basis for verifying plant and part identification, the definition of the extracted fraction, confirmation of individual constituents, and labeling units.
Article 1 (Purpose)
The purpose of this Standard is to evaluate plant identity, the part used and processing provenance, extract form, the definition and content of silymarin, stability, authenticity and contaminant testing, and cautionary statements for health foods containing milk thistle or silymarin.
Article 2 (Scope)
This Standard applies to the parts of Silybum marianum traded as fruits or seeds, their powders, extracts with or without oils and fats, and oral products formulated with these materials. Leaves, stems, and other parts shall not be treated as fruit-derived raw materials, and a single isolated constituent shall not be labeled as the entirety of silymarin.
Article 3 (Terms and Definitions)
- 1. Milk thistle raw material: A powder or processed material obtained from a specified part of identified Silybum marianum.
- 2. Silymarin: A constituent fraction for which the analytes to be quantified are defined, including silybins, isosilybins, silychristins, silydianin, and other constituents.
- 3. Constituent profile: Analytical information showing the identity and relative distribution of the multiple constituents that make up silymarin.
- 4. Extract amount: The amount of the fraction after extraction, concentration, and drying, distinguished from the amount of carriers and the amount of silymarin.
- 5. Fruit-equivalent amount: A value obtained by converting the extract amount to the amount of source plant material on the basis of the extraction ratio or similar information.
Article 4 (Requirements)
- 1. The source plant shall be specified by scientific name, part used, cultivation or collection area, post-harvest treatment, and lot. Before powdering, morphological characteristics shall be compared with reference specimens; after powdering or extraction, chemical fingerprints and, where necessary, genetic information shall be compared with reference specimens. The presence of other plant species or parts shall not be ruled out solely on the basis of a single color reaction.
- 2. Whole fruit powder, defatted material, oil and fat fractions, and extracts containing silymarin shall be distinguished. Extraction solvents, the relationship between raw material and extract, defatting, concentration, refining, and drying carriers shall be recorded in process documentation, and the calculation basis for fruit-equivalent labeling shall be retained. The input weight of the source plant material shall not be treated as the actual amount of extract or silymarin.
- 3. Silymarin specifications shall define the constituents included in the total amount, reference substances, detector responses, and summation method. Items appropriate to the manufacturing method shall be selected from silybin isomers, isosilybin, silychristin, silydianin, and other constituents, and shall be separated and confirmed. The authenticity of the fraction shall not be determined solely by overall absorbance. Each specification shall be established by the business operator on the basis of reference lots and analytical performance, and its basis shall be presented.
- 4. Content labeling shall clearly state the amount of fruit powder or extract per recommended daily intake. Where silymarin is declared, the mass unit, constituents included in the sum, and definition under the measurement method shall also be stated. Values calculated from the content percentage in the extract, values measured in the final product, and raw material weight including drying carriers shall be distinguished. The amount of a single constituent shall not be reinterpreted as total silymarin content.
- 5. Product quantification shall examine the effects of flavonoids from other plants, oils and fats, coatings, and coloring constituents on extraction recovery and separation. Where reference substances for individual constituents show different responses, conversion factors and the treatment of uncertainty shall be recorded. Spike recovery data for each dosage form, or equivalent documentation, shall confirm that quantification does not rely solely on calculations from raw material certificates of analysis.
- 6. Stability evaluation shall consider temperature, humidity, light, oxygen, and liquid properties within the product, and shall track changes in selected constituents as well as total silymarin content. The effects of moisture absorption by the extract, reactions within tablets, or precipitation in liquid products on uniform sampling shall also be evaluated where applicable. The business operator shall establish specifications corresponding to the packaging and storage conditions.
- 7. Test items shall include plant and part identity, constituent profiles, and quantification of the constituents subject to labeling. Test items shall be selected from pesticides, mycotoxins, heavy metals, microorganisms, residual solvents, and other substances on the basis of the cultivation location and extraction process. Where oils and fats derived from seeds or fruits are present, their oxidation state shall also be considered. The basis for selection, including items excluded from testing, the methods, and limits of quantification shall be recorded.
- 8. Labeling shall consistently state the common or scientific name, part used, whether the material is a powder or extract, the definition of silymarin, content units, and storage instructions. Allergens originating from raw materials or excipients shall be evaluated. Advice to seek consultation for pregnant or breastfeeding persons, persons using medicinal products, or persons under medical supervision, and instructions to discontinue use in the event of adverse symptoms, shall be provided in accordance with the latest official information and product-specific evaluation.
Article 5 (Evaluation Categories)
- Conformity: The plant species and part used, extract form, definition of silymarin constituents, product content, and testing according to process are consistently linked within a single set of lot documentation.
- Partial conformity: Plant identification and total content labeling can be confirmed, but separation of constituents or recovery from the product is insufficient, and a plan to address the deficiencies has been presented.
- Nonconformity: Fruit amount, extract amount, and silymarin amount are confused, the constituents included in the sum are not defined, or the extracted fraction is assessed solely by a single reaction.
Article 6 (Implementation)
The business operator may issue a self-declaration of conformity on the basis of plant receipt documentation, part verification, extraction steps, constituent analysis, measurements in the product, and storage testing. Upon application, the Council may verify traceability from the declared silymarin content to the reference substances, extraction lot, and source plant material lot. Reevaluation shall be conducted when the place of origin, part used, defatting or extraction conditions, carrier, dosage form, or quantitative method is changed.
Supplementary Provisions
This Standard shall take effect on 3 September 2026.
※ This Standard sets out evaluation criteria for information disclosure and quality management practices and does not guarantee the efficacy or safety of individual products.