Standardization & Marker Compounds
What standardization and marker compounds such as withanolides, ginsenosides, rosavins and salidroside mean on adaptogen labels, and what tests of products found.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read who should be careful, by situation before you use anything on this page.
"Standardized to 5%" sounds precise. This page explains what a marker compound is, which markers go with which adaptogen, and how often tested products matched their labels. A marker is a measurement, not a promise that a product helps with stress, energy or sleep.
What a marker compound is
A marker compound is a chemical that scientists use to identify a plant or to check consistency. It may or may not be what causes any effect. NIH describes ginsenosides in Asian ginseng as the substances "thought to be most important," which is a belief, not a finding. [1] NIH also says that a maker's use of "standardized" does not necessarily guarantee product quality or consistency. [2]
Markers by herb
| Herb | Markers named in the sources | What the source says |
|---|---|---|
| Ashwagandha (Withania somnifera) | Withanolides, such as withanolide A and withaferin A [3] | NIH: a group of bioactive compounds [4] |
| Asian ginseng (Panax ginseng) | Ginsenosides | NIH: thought to be most important [1]; one EU extract entry is defined by 4% ginsenosides (sum of eight named ones) [5] |
| Rhodiola (Rhodiola rosea) | Rosavin (and related rosavins) and salidroside | Rosavin was used to tell R. rosea from related species [6] |
| Eleuthero (Eleutherococcus senticosus) | Eleutherosides | Not described in the sources we read |
Markers also differ by plant part, species and processing. In one plant study, ashwagandha leaves and roots were highest in different withanolides. [7] Steaming ginseng changes which ginsenosides are present. [8]
Do products match their labels?
| Herb | Finding | Strength |
|---|---|---|
| Rhodiola | In fewer than a quarter of products were the labeled salidroside and total rosavins confirmed [9] | One lab study of products and species |
| Rhodiola | About one fifth of products claiming R. rosea had no rosavin [6] | One study, European market |
| Ashwagandha | Only 10 of 25 supplements met both pharmacopoeia standards in the study [3] | One study, 25 products |
Part of the ashwagandha failure was a testing problem: a leaf compound was measured together with withanolide A and led to underestimation. [3] So test methods themselves matter, which is a reason to look at which method a certificate used. See Testing and certificates of analysis.
Marker amount is not clinical benefit
NIH says many ashwagandha trials were small and used a variety of preparations. [4] For rhodiola, NIH says there is not enough reliable evidence to determine whether it or its components are useful for any health-related purpose. [10] Proper evidence not found, in the sources we read, showing that a higher marker percentage predicts a better outcome in people. Trials and their markers are on Active compounds and Standardized extracts.
Frequently asked questions
What does "standardized" mean?
Generally that a marker was measured. NIH says it does not necessarily guarantee quality or consistency. [2]
Are withanolides proven to cause ashwagandha's effects?
Not established in the sources we read. NIH notes only that they are bioactive compounds. [4]
Why do two products with the same percentage differ?
Species, plant part, solvent and test method can all differ. [3]
Is a higher percentage better?
Proper evidence not found.
How do I check a label?
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety
A high marker percentage is not a safety signal. Rare liver injury reports exist for ashwagandha supplements, and NIH says it is not recommended before surgery or with autoimmune or thyroid disorders. [4] Rhodiola interaction with losartan has been reported. [10] Ask a pharmacist, and see medication interactions.
References
- NCCIH, Asian Ginseng: Usefulness and Safety (last updated February 2025). https://www.nccih.nih.gov/health/asian-ginseng. Read 2026-10-23.
- NCCIH, Using Dietary Supplements Wisely (last updated January 2019). https://www.nccih.nih.gov/health/using-dietary-supplements-wisely. Read 2026-10-23.
- Avula B, et al. A comparison of British and US Pharmacopoeia standards for quality of ashwagandha dietary supplements in commerce. Phytother Res. 2026;40(8):4833-4844. Read 2026-10-23.
- NCCIH, Ashwagandha: Usefulness and Safety (last updated March 2023). https://www.nccih.nih.gov/health/ashwagandha. Read 2026-10-23.
- European Medicines Agency (HMPC), European Union herbal monograph on Panax ginseng C.A.Mey., radix, final revision 1, 29 May 2024. Read 2026-10-23.
- Booker A, et al. The authenticity and quality of Rhodiola rosea products. Phytomedicine. 2016;23(7):754-762. Read 2026-10-23.
- Ankad GM, et al. Traditional horticulture practices increase the production of selected withanolides in Withania somnifera. J Chromatogr Sci. 2020;58(10):899-906. Read 2026-10-23.
- Shin JH, et al. Change of ginsenoside profiles in processed ginseng by drying, steaming, and puffing. J Microbiol Biotechnol. 2019;29(2):222-229. Read 2026-10-23.
- Marchev AS, et al. Authenticity and quality evaluation of different Rhodiola species and commercial products based on NMR-spectroscopy and HPLC. Phytochem Anal. 2020;31(6):756-769. Read 2026-10-23.
- NCCIH, Rhodiola: Usefulness and Safety. https://www.nccih.nih.gov/health/rhodiola. Read 2026-10-23.