Heavy Metals in Supplements and Herbal Products: What Testing Found
What published testing found about lead, mercury, arsenic and cadmium in supplements and herbal products, including Ayurvedic and Chinese products, and what the studies cannot tell you.
Content last updated . This page has not been medically reviewed.
If someone may be poisoned, call 911 for collapse, seizure or trouble breathing, or Poison Help at 1-800-222-1222 (US). See Poisoning: What to Do First.
Some supplements and herbal products tested in published studies contained lead, mercury, arsenic or cadmium, and in some samples the amount was above a safety standard. Other studies found low levels. The results depend on the product type, where it came from and how the samples were chosen, so no single percentage describes "supplements" as a whole. Proper evidence not found for an overall rate across the US market; we searched PubMed, Europe PMC, NCCIH and FDA pages.
"Heavy metals" here means metals such as lead, mercury, arsenic and cadmium, which can be toxic.
What the official health pages say
- NCCIH: some Ayurvedic preparations may contain lead, mercury or arsenic in amounts that can be toxic. [1] It adds that FDA warns the presence of metals in some Ayurvedic products makes them potentially harmful. [1]
- NCCIH: some Chinese herbal products have been contaminated with toxic compounds, heavy metals, pesticides and microorganisms. [2]
- FDA has warned when certain kratom products had concerning levels of heavy metals. [3]
Respect for traditional practice
In Ayurveda, one traditional practice, rasa shastra, combines herbs with metals, minerals and gems. [4] That is a traditional preparation method and is described here on its own terms. The question the studies ask is a modern safety one: how much of a metal ends up in a product people swallow, and is it above a standard? In the two Saper surveys below, about four in five products had no detectable lead, mercury or arsenic, and metals also turned up in US-made products. [5][4]
What testing found
These are observational product surveys. They show what was in the samples tested, not how many people were harmed.
| Study | Products tested | What it found | Limits |
|---|---|---|---|
| Saper 2004 (Boston, US) | 70 Ayurvedic products made in South Asia and bought in local stores in 2003 | 14 (20%) contained lead, mercury and/or arsenic; if taken as directed each could exceed regulatory standards. [5] | One city, one period. |
| Saper 2008 (online) | 193 Ayurvedic medicines bought online in 2005 | 20.7% contained metals; similar in US-made (21.7%) and Indian-made (19.5%) products; higher in rasa shastra products (40.6% vs 17.1%). [4] | Online sellers in 2005. |
| Mikulski 2017 | 252 Ayurvedic samples gathered during a lead-poisoning investigation | Lead in 65%, mercury in 38%, arsenic in 32%. [6] | Collected in an investigation, so not a random sample of the market. |
| Coghlan 2015 | 26 traditional Chinese medicines | Heavy metals including arsenic, lead and cadmium, one with arsenic more than 10 times the acceptable limit. [7] | Small sample. |
| Dolan 2003 | 95 dietary supplements | Reported ranges for arsenic, cadmium, mercury and lead; one product reached 48,600 micrograms per kilogram of lead. [8] | Published in 2003, so older products. |
| Hedegaard 2013 (Denmark) | 16 supplements from herbs, other botanicals and algae | In the worst case, inorganic arsenic from the recommended dose of one product was 62.4% of a benchmark range set by EFSA. [9] | Small sample. |
| Jairoun 2020 (UAE) | 277 supplements | Average daily intakes of cadmium, lead and arsenic were below the acceptable daily intakes. [10] | Authors note people may take several products, so exposure can add up. |
NCCIH also cites a 2015 survey of people who use Ayurvedic preparations in which 40 percent had elevated blood lead levels, and a 2015 case report linking elevated blood lead in a 64-year-old woman to preparations bought on the internet. [1]
What the studies cannot tell you
- A result for one product does not apply to another product, brand or batch. We name no brands.
- Finding a metal is not the same as finding a harmful amount. The Saper studies compared estimated daily intakes with regulatory standards to judge that. [5]
- The studies are from different years and countries. They cannot show what is on a shelf today.
- Supplement category, dosage form and country of origin were strong determinants of contamination in the UAE study. [10]
Who should ask a clinician
Anyone who uses imported or traditional medicine products regularly, and anyone who is pregnant, breastfeeding or giving products to children, can ask a pharmacist or clinician about them. NCCIH advises talking to your conventional health care provider before using Ayurvedic products. [1] The sources above did not give us a safe amount for a person, so we give none. A clinician decides whether any testing is appropriate.
Where to go next
Frequently asked questions
Do all Ayurvedic or Chinese herbal products contain heavy metals?
No. In Saper 2004, 14 of 70 products (20%) contained metals. [5] In Coghlan 2015, 26 traditional Chinese medicines were tested, and heavy metals were found in some. [7]
Are US-made products free of heavy metals?
Not necessarily. Saper 2008 found similar rates in US-made (21.7%) and Indian-made (19.5%) Ayurvedic products bought online. [4]
Why can plant products contain metals?
One source we read says metals may be present in some Ayurvedic medicines because of the rasa shastra practice. [4] Why metals turn up in other products is not described in the sources we read.
Do seals and testing programs solve this?
They can help, but they show only what they test. See Third-Party Testing and Certifications.
What if I think I have been exposed?
Call Poison Help at 1-800-222-1222 (US), or 911 if the person is very unwell. Tell a clinician about every product you use. Do not stop a prescribed medicine on your own; ask the prescriber or pharmacist.
References
- National Center for Complementary and Integrative Health (NCCIH). Ayurvedic Medicine: In Depth. Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH). Traditional Chinese Medicine: What You Need To Know. Read 2026-10-22.
- U.S. Food and Drug Administration. FDA and Kratom. Read 2026-10-22.
- Saper RB, et al. Lead, mercury, and arsenic in US- and Indian-manufactured Ayurvedic medicines sold via the Internet. JAMA. 2008. Read 2026-10-22.
- Saper RB, Kales SN, Paquin J, et al. Heavy metal content of ayurvedic herbal medicine products. JAMA. 2004;292(23):2868-73. Read 2026-10-22.
- Mikulski MA, Wichman MD, Simmons DL, Pham AN, Clottey V, Fuortes LJ. Toxic metals in ayurvedic preparations from a public health lead poisoning cluster investigation. Int J Occup Environ Health. 2017;23(3):187-192. Read 2026-10-22.
- Coghlan ML, Maker G, Crighton E, et al. Combined DNA, toxicological and heavy metal analyses provides an auditing toolkit to improve pharmacovigilance of traditional Chinese medicine (TCM). Sci Rep. 2015;5:17475. Read 2026-10-22.
- Dolan SP, Nortrup DA, Bolger PM, Capar SG. Analysis of dietary supplements for arsenic, cadmium, mercury, and lead using inductively coupled plasma mass spectrometry. J Agric Food Chem. 2003. Read 2026-10-22.
- Hedegaard RV, Rokkjaer I, Sloth JJ. Total and inorganic arsenic in dietary supplements based on herbs, other botanicals and algae. Anal Bioanal Chem. 2013. Read 2026-10-22.
- Jairoun AA, Shahwan M, Zyoud SH. Heavy Metal contamination of Dietary Supplements products available in the UAE markets and the associated risk. Sci Rep. 2020. Read 2026-10-22.