Heavy metals in herbal supplements, the real picture

Heavy metals in herbal products get discussed in two unhelpful registers. One treats every herbal supplement as a poisoning risk. The other treats the whole subject as a conspiracy against traditional medicine.

Neither is useful if you are buying a product or having one made.

So this is the middle version: where the metals actually come from, which products carry more risk and why, what the testing can and cannot establish, and how to read a report.

This is general information, not medical advice. If you are concerned about an exposure, see a doctor, blood lead and other exposure tests exist and are the only way to answer the question for a person. Do not stop prescribed medicines on your own.

The four metals that matter

Lead, arsenic, cadmium and mercury. Different sources, different risks, different reasons for appearing.

And they appear through three completely different routes, which is the distinction most coverage misses.

Route one: the soil, and it is unavoidable

Plants take up what is in the ground they grow in.

Industrial areas, roadside cultivation, land irrigated with contaminated water, and areas with naturally high geological arsenic all produce crops with measurable metal content. Parts of the Indo-Gangetic plain have well-documented groundwater arsenic, and that reaches plants grown there.

This is why “organic” does not mean “low in heavy metals”. Organic certification governs inputs, pesticides, fertilisers, GMOs. It does not govern the geology, and an organically grown root in contaminated soil carries the metals anyway.

It is also why roots carry more than leaves, as a general tendency. The root is the organ in contact with the soil, and it is where the plant stores. Ashwagandha, shatavari, giloy stem, turmeric rhizome and other underground parts are the higher-attention category for this reason alone.

And why concentration matters. A 10:1 extract concentrates whatever was in the raw material roughly tenfold, metals included, unless the extraction process removes them, which depends on the solvent and the chemistry and should not be assumed.

Route two: the process

Added, not absorbed.

Grinding equipment, particularly older mills, can contribute metal. Pigments and colourants used to improve appearance have historically been a lead source, chrome yellow in turmeric is the well-documented case. Weighting agents added to increase mass. Contaminated water used in processing. And storage in unsuitable containers.

This route is controllable, and a manufacturer who has thought about it can tell you how.

Route three: deliberate, in mineral preparations

And this needs stating plainly, without either defending or dismissing it.

Some classical Ayurvedic preparations contain metals and minerals by design. Bhasma preparations are made from metals and minerals processed through specific classical procedures, and the tradition holds that the procedures transform them.

What is true regardless of the classical position: a product containing an intentionally added metal is a completely different risk category from a product that absorbed metal from soil, and it needs to be treated as such. It needs the correct licence, it needs the preparation to have actually followed the classical method, and it needs to be used under qualified supervision rather than bought casually online.

And a “classical” mineral product sold as a wellness supplement, without the licence and without supervision, is the single most concerning thing in this field. We do not make them, and we are not neutral about that.

The relevance for everyone else: when a published survey finds high metal content in “Ayurvedic products”, a significant part of the finding often comes from this category, not from a turmeric capsule. Conflating the two misleads in both directions.

Which products deserve more attention

In rough order, from what we see.

Shilajit. Highest attention category among the popular products. It is a geological material, its metal content depends entirely on where it came from, and the market has heavy adulteration. Batch-wise heavy metal certification is not optional here, and “sourced from the Himalayas” is marketing, not a test result.

Mineral and bhasma preparations, for the reasons above.

Root-based products, including ashwagandha, shatavari and others, manageable with sourcing and testing, but a real category.

Concentrated extracts of any root, because of the concentration arithmetic.

Spirulina and algae products, mainly a cyanotoxin concern rather than metals, but they share the “grown in water of unknown quality” problem, and microcystin testing belongs on the certificate.

Turmeric, historically, because of the colourant issue.

And wild-collected material generally, where the collection site is unknown and varies lot to lot.

What the limits are, and why we are not printing them

There are prescribed limits under the applicable Indian regulations, and there are different limits in export destinations, frequently stricter, and expressed differently.

We are deliberately not printing numbers, for two reasons.

They change, and an article with a stale limit is worse than one with none.

And they are expressed in ways that are easy to misread, parts per million in the raw material, versus a daily intake limit, versus a limit per serving. A product can meet a raw-material ppm limit and still deliver more than a daily intake limit if the serving size is large.

So the useful instruction is: ask which limit the result is being compared against, and ask whether the comparison accounts for the serving size. That question separates a meaningful certificate from a decorative one.

How to read a heavy metals report

Six things, and a report missing any of them is not telling you much.

A batch number that matches the pack in your hand. A report for “the product” rather than a batch is a marketing document.

The four metals, named individually, with numbers. Not “heavy metals: complies”.

The method, typically ICP-MS or AAS. The method determines the detection limit, and a result of “not detected” means nothing without knowing what the limit of detection was.

The matrix tested. Finished product, or raw material? A clean raw material report says nothing about what the process added, and a finished-product report is what you actually consume.

The laboratory and its accreditation. NABL accreditation for the specific test, ideally; an in-house result is weaker evidence.

And the date, with the limit the result is compared against.

Then the question you ask on top of all that: is this done every batch, or was it done once? Because soil varies by field and by season, and a single historical certificate for an agricultural product is a snapshot, not a control.

What testing cannot establish

Being fair about the limits of the thing we are recommending.

A certificate covers the batch tested, and within that batch, the sample tested. Sampling plans matter, and a non-representative sample from a poorly blended lot can pass while the lot does not.

It says nothing about the next batch.

It does not cover other contaminants, pesticide residues, mycotoxins, microbiology and undeclared pharmaceuticals are separate tests, and the last of those is the one that actually sends people to hospital.

And it does not tell you about cumulative exposure. You eat food, drink water and may take several supplements. Each may be individually compliant, and the total is what reaches you. This is a real argument for taking fewer products rather than more, and it is an argument we make against our own commercial interest.

If you are a brand owner

Four concrete things.

Specify heavy metals testing per batch in your agreement, with the method, the four metals individually, and the limits for your target markets, including export destinations if those are in your plan.

Test the finished product, not only the raw material.

Commission some independent testing of your own, on batches you did not choose in advance. We have written separately about how to do that.

And do not accept “complies with limits” as a certificate. Ask for numbers. A manufacturer who will not give you numbers for your own product is telling you something.

If you are buying for yourself

When to be careful rather than worried.

Be careful with shilajit, mineral preparations, and anything concentrated, from a brand that will not send you a batch report.

Email the brand with the batch number and ask for the heavy metals and microbiology report. The ones that send it are demonstrating the only thing worth demonstrating. The ones that deflect have also answered.

Be more careful if you are pregnant, planning pregnancy, or buying for a child, because the exposures that matter most are the ones during development.

And see a doctor rather than guessing if you have been taking a mineral preparation long-term, or a product that worked unusually fast and strongly. Exposure testing exists, and the question is answerable.

When to see a doctor

Soon, if you have taken a mineral or bhasma preparation for months without qualified supervision; if you have unexplained abdominal pain, persistent fatigue, anaemia, or tingling in the hands and feet alongside long-term supplement use; or if a child in the household has been taking any such product.

Urgently, for severe abdominal pain with vomiting, confusion, seizures, or sudden weakness, and take the product and its pack with you, because the label and the batch number are useful clinical information.

The short version

1. Neither a scare story nor nothing
2. Four metals matter: lead, arsenic, cadmium, mercury
3. Three different routes in, and most coverage conflates them
4. Soil uptake is unavoidable and depends on where it grew
5. Industrial land, roadside cultivation and natural geological arsenic all contribute
6. “Organic” does not mean low in heavy metals, it governs inputs, not geology
7. Roots tend to carry more than leaves, being in contact with the soil
8. A 10:1 extract concentrates the metals roughly tenfold too
9. Process contamination: old mills, colourants, weighting agents, bad water
10. Chrome yellow in turmeric is the documented colourant case
11. And some classical mineral preparations contain metals by design
12. That is a different risk category and needs licence and supervision
13. A mineral product sold casually as a wellness supplement is the real concern
14. Surveys of “Ayurvedic products” often draw heavily on that category
15. Highest attention: shilajit, mineral preparations, roots, concentrates
16. “Sourced from the Himalayas” is marketing, not a test result
17. Spirulina adds a microcystin question to the certificate
18. Limits change and differ by market, so ask which limit was applied
19. Raw-material ppm and daily intake limits are not the same thing
20. A large serving can pass one and exceed the other
21. A report needs a batch number matching your pack
22. All four metals named individually with numbers, not “complies”
23. The method, because it sets the detection limit
24. “Not detected” means nothing without the limit of detection
25. Finished product, not just raw material
26. An accredited laboratory, with the date and the limit compared against
27. And every batch, not once, soil varies by field and season
28. Testing covers the sample, in the batch; sampling plans matter
29. Pesticides, mycotoxins and undeclared drugs are separate tests
30. Undeclared pharmaceuticals are what actually send people to hospital
31. Cumulative exposure across food, water and several products is real
32. Which argues for fewer products, against our own interest
33. Brand owners: specify per-batch testing with methods and numbers in the agreement
34. And commission some independent testing on batches you did not choose
35. Buyers: email the brand with the batch number and ask for the report
36. Be more careful in pregnancy, when planning it, and for children
37. Long-term mineral preparation use without supervision, see a doctor
38. Take the pack with you; the label and batch number are clinical information

Related guides: how to choose a contract manufacturer, supplement label compliance in India. Related reading: how to commission independent testing, the five most adulterated herbal ingredients in India, reading a certificate of analysis, and मिलावट वाले हर्बल प्रोडक्ट कैसे पहचानें.