Standardized Extracts
What "standardized" means on adaptogen labels, which marker compounds are named (withanolides, rosavins, salidroside, ginsenosides), and what a marker number does and does not show.
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A standardized extract is an extract that a laboratory has measured for one or more "marker" compounds, so a label can state how much of the marker is in it. The number is a measurement of the product. It is not a measurement of how well the product works.
The short answer. A marker percentage helps you compare what is in two products. Whether the product helps with stress, fatigue or sleep is a separate question that only human trials of that exact extract can answer. A rhodiola laboratory study put it this way: standardized marker content is necessary for quality control, but insufficient for assessing potential efficacy. [1]
Markers named in the sources
| Plant (scientific name) | Part | Marker named by the source | Source |
|---|---|---|---|
| Ashwagandha (Withania somnifera) | Root, leaf, or both | Withanolides, a group of substances in the plant | [2] |
| Asian ginseng (Panax ginseng) | Root | Ginsenosides (or panaxosides), thought to be the most important substances | [3] |
| Rhodiola (Rhodiola rosea) | Rhizome and root | Salidroside and rosavin | [1] |
Scientific names were checked against the GBIF taxonomy. [4] Ginseng here means Panax ginseng. American ginseng and eleuthero are different plants, and a result for one does not transfer to another (see ginseng types compared).
What the labeling guide allows
The FDA says a US label may list constituents of a dietary ingredient with their amounts per serving. [5] It says a liquid extract label may include the concentration of the dietary ingredient and the solvent used, and must identify the solvent. [5] It says a dried extract is listed by the weight of the dried extract. [5] The guide sections we read do not set marker levels.What laboratory studies of real products found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Do commercial ashwagandha products pass pharmacopoeia tests? | Of 25 supplements, over 44% failed British Pharmacopoeia standards and 60% failed United States Pharmacopeia standards. The authors attribute many failures to a compound found mainly in leaf, and say only two products were confirmed as root-derived. [8] | One laboratory analysis |
| Do commercial rhodiola extracts match in markers? | Seven extracts showed a high degree of variation in marker content; one lacked rosavin. [1] | Laboratory study; part of the work used isolated brain tissue slices |
| Do ginseng products vary? | Total ginsenosides ranged from 5.3 to 18.2 mg per serving across brands. [9] | Small study from 2004 |
| Can a standardized extract have a trial record? | A review of one specific standardized ginseng extract (G115) says ginseng products on the market show high variability, and that standardization is central to reproducible quality. [10] | Review of one extract; we did not check funding. Its findings belong to that extract only |
Frequently asked questions
Does "standardized to 5% withanolides" mean it works better?
No source we read says so. A percentage describes what a lab measured. For rhodiola, a laboratory study said marker content is insufficient to assess potential efficacy. [1]
Are standardized extracts safer?
Not described in the sources we read. Standardization concerns content, not safety. NIH's ashwagandha cautions apply to the plant's supplements in general. [2]
What is a marker compound?
A substance chosen to measure in an extract, such as withanolides in ashwagandha or ginsenosides in ginseng. NIH calls ginsenosides the substances thought to be most important in Asian ginseng. [3]
Why do two labels with the same percentage differ?
Not described in the sources we read for different brands. In the 2026 ashwagandha analysis, a compound found mainly in leaf samples caused withanolide A to be underestimated, so the measuring method matters. [8]
Should a child or pregnant person use a standardized extract?
NIH says to avoid ashwagandha in pregnancy, and the EU monographs we read do not recommend rhodiola or ginseng products for those under 18, and say safety in pregnancy and breastfeeding is not established. [2][6][7] Ask a clinician. See children and teens.
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.
How regulators describe extracts
- Rhodiola, EU, 2024: the monograph lists a dry extract with a stated ratio (written DER 1.5-5:1), made with 67 to 70 percent ethanol, and says a narrower ratio is to be specified for an individual product. [6] It describes use in terms of long-standing traditional use for relief of stress symptoms, not a proven clinical benefit. [6]
- Ginseng, EU, 2014 (marked superseded): one listed extract is made with 40 percent ethanol and contains 4 percent ginsenosides, as the sum of eight named ones. [7] Other listed extracts are made with different solvents.
Because the monographs describe preparations, they show how much the "same" plant can vary. They are not a guide to buying. For the ratio itself see extract ratios explained and standardization and marker compounds.
Limits and uncertainty
- A marker number can be correct while the product still differs from the one tested in studies. NIH says supplements from stores or online may differ in important ways from products tested in studies. [11]
- The ashwagandha analysis said the compound found mostly in leaf samples caused withanolide A to be underestimated. [8] That means a measurement method matters as much as the label number.
- Proper evidence not found for trials that compare standardized and non-standardized extracts of the same adaptogen head to head. We searched PubMed for that and found none.
Who should ask a clinician
References
- Assessing the quality and potential efficacy of commercial extracts of Rhodiola rosea L. by analyzing the salidroside and rosavin content and the electrophysiological activity in hippocampal long-term potentiation. Front Pharmacol. 2018. PubMed 29881348 (abstract read; seven commercial extracts, laboratory study). Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Ashwagandha: Usefulness and Safety. Last updated March 2023. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Asian Ginseng: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- Global Biodiversity Information Facility. GBIF Backbone Taxonomy species match (checked for Withania somnifera, Panax ginseng, Rhodiola rosea, Lepidium meyenii, Phyllanthus emblica). Read 2026-10-23.
- U.S. Food and Drug Administration. Dietary Supplement Labeling Guide: Chapter IV. Nutrition Labeling. Read 2026-10-23.
- European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Rhodiola rosea L., rhizoma et radix, Final, Revision 1. EMA/HMPC/24177/2023, adopted 20 March 2024. Read 2026-10-23.
- European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Community herbal monograph on Panax ginseng C.A. Meyer, radix. EMA/HMPC/321233/2012 Corr.1, 25 March 2014. The copy we read is marked "Superseded". Read 2026-10-23.
- A comparison of British and US Pharmacopoeia standards for quality of ashwagandha dietary supplements in commerce. Phytother Res. 2026. PubMed 41386716 (abstract read). Read 2026-10-23.
- Phytochemical assays of commercial botanical dietary supplements. Evid Based Complement Alternat Med. 2004. PubMed 15841264 (abstract read). Read 2026-10-23.
- The G115 standardized ginseng extract: an example for safety, efficacy, and quality of an herbal medicine. J Ginseng Res. 2020. PubMed 32148399 (abstract read; a review centred on one specific standardized extract). Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Using Dietary Supplements Wisely. Last updated January 2019. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Rhodiola: Usefulness and Safety. Last updated April 2025. Read 2026-10-23.