There are toxic heavy metals in prenatal supplements?

Done for you pre-written health content


There are toxic heavy metals in prenatal supplements?


heavy metals prenatal supplements


Short answer: Yep, there are toxic heavy metals in prenatal supplements.

Long answer: It’s not necessarily as bad as it sounds. Read on…

You may have heard the recent study called: Heavy metal contamination of prenatal vitamins.

My first reactions were:

  • Is this true? #skeptical
  • Is it relevant to me or people I know? #applicable
  • As a health & wellness pro, what should I advise? #crediblerecommendation

ASIDE: The reason I wanted to go over this study on my blog is that, not only am I trained in toxicology and nutritional science at the Master’s level, but I also worked in product safety in the health products industry, including with supplements, for 12 years. Not to mention the fact that I took Canadian prenatal vitamins for my pregnancies. This study totally piqued my interest!

What are the results of the study?


• Toxic elements are found in prenatal vitamins with lead at unacceptable levels in more than half of the products tested.

• Arsenic is also found in some products at unsafe levels.

• Thallium is present at levels in some products that are not acceptable.

• Some products have very low level, which are safer, and recommendations are made to have industry (self regulatory) and government oversight to have the least contamination of prenatal vitamins.




  • Yes, it’s true – there are unsafe levels of heavy metals found in certain supplements;
  • They’re found in all 26 Canadian prenatal supplements tested;
  • The researchers haven’t disclosed which brands have which amounts of which metals;
  • Some of the more expensive or “organic,” “non-GMO,” and “pesticide-free” brands did not have lower levels than some inexpensive commercial brands (but, the researchers did not disclose which brands had which levels of which metals in them);
  • We don’t know where the contamination is coming from;
  • Right now the health risks are all potential, not proven. We don’t know that these supplements are linked with any concerns for either moms or babies – more research is needed.
  • What to do? Make sure to get enough essential minerals, as this can help to reduce the amount of toxic metals absorbed into the body;
  • The researchers are calling on industry and the government to ensure these levels of heavy metals are addressed.

Read on to find out how I dove into the study so you can too. #nerdalert


Is it true – Are there toxic heavy metals in prenatal supplements?


This is the first question I always ask myself: Is it true?

Is this news real or fake? Is this science good or bad?

There are a few ways to spot: 1) bad science, and 2) bad media/internet coverage of good science. An infographic I love is here:

Let’s start with the bad media/internet coverage first.

Bad media/internet coverage?

Sensationalized Headlines? Misinterpreted results? Selective reporting of data?

I haven’t seen any press coverage of this study, so I don’t know if/how the media and internet personalities are talking about this. I haven’t seen headlines of any sort, let alone sensationalize ones. If you have, link them in the comments below, I’d love to see them!


Bad Science?

You can read and/or download the whole study right here:

Before we dive into the study, and how you can critically analyze it, let’s first understand what the researchers looked at. Here’s what this study did:

This study was designed to research the possibility of toxic element contamination in a variety of commonly consumed prenatal supplements – a product ingested by most women in the developed world during gestation and lactation.


This study was just published in the peer-reviewed medical journal called Toxicology Reports.

Peer-review is important for a few reasons. The whole process of doing science is to look at or test ideas by removing subjective opinions and personal experiences – in other words – removing bias.

In order to do this, scientists publish their work in journals for scrutiny from other scientists. Literally – they put their work out there to be criticized!

Scientists publish their work in journals for scrutiny from other scientists. Literally - they put their work out there to be criticized! #science #research #publish Click To Tweet

First, their work is reviewed by their peers – other scientists in the same field. Then, if/when it’s accepted for publication in the journal, it goes out to the world so thousands of other scientists (and others who understand the language of “science-ese”) can comment on it.

Over and above these, each study outlines the methods used to do the research. What type of study, what type of statistics, etc.?

Everything goes out there for scrutiny.

Unfortunately, some researchers, instead of publishing in peer-reviewed journals, publish their works in “predatory journals.” These are essentially “pay to play” money-making journals that will publish anything they get – for a fee. These journals are NOT peer-reivewed and are NOT indexed in PubMed (PubMed only accepts the high-quality journals for their database).

Another thing some researchers do instead of publishing in a peer-reviewed journal, they publish a book, or online program, or create a product to sell.

PRO TIP: If you come across a health or medical study that’s not found in PubMed – beware!

PRO TIP: If you come across a health or medical study that's not found in PubMed - beware! #research #study #health Click To Tweet

If you’ve heard that peer review isn’t perfect – it’s not! Having said that, it really is one good way to ensure there is a minimum quality standard for health studies published in credible journals.

Conflicts of interest?

This is an easy find – but it’s not the only or the best way to know if a study was done well.

For the past several years, medical journals have required disclosure of conflicts of interest. You can usually find those close to the bottom of the study.

Don’t give these too much weight! They’re really just one of several things about a study that can make it less-than-ideal. Plus, just because someone’s study is funded by an interested party doesn’t mean they absolutely had influence on the outcome of the study. It’s possible, but not the only, nor the most important thing to consider.

Here’s how this study stacks up:

Funding and conflicts of interest – There are no conflicts of interest. The first and second author shared the cost for the toxicological testing at ALS labs.

According to this, this study is free of conflicts of interest, which is nice to know.

Unrepresentative samples used?

The interesting thing about this study is that the samples used ARE representative of prenatal supplements available in Canada.

And, if they’re available in Canada, they might also be the same ones available in the US and elsewhere – possibly.

This study is NOT representative of:

  • Regular multivitamins or other supplements available in Canada;
  • Other toxins that were not tested for in these supplements;
  • Non-Canadian supplements available or used in other countries; nor,
  • Any people who may have taken these supplements – this was an analytical chemistry study only – not one that looked at health outcomes in anyone at all.

This principle goes for every health study – what exactly did the study look at – what did it represent? Research can done in an infinite number of ways, so we need to look at what it actually represents.

What exactly did the study look at? Research can done in an infinite number of ways, so we need to look at what it actually represents. #research #method #study Click To Tweet

For example:

  • Studies done on adults don’t necessarily apply to children or older adults;
  • Studies done on a specific culture of people don’t necessarily apply to every other culture;
  • Studies done with supplements don’t necessarily apply to foods that contain those nutrients;
  • Studies done with eating/drinking/swallowing something don’t necessarily apply to other delivery methods like injections or IVs,
  • Studies done on people with a condition don’t necessarily apply to preventing that condition in healthy people;
  • Studies done on athletes don’t necessarily apply to the general population; and,
  • Studies done in animals or cells don’t apply to people.

You get the point. 🙂

So, since this study was not even done in people, just testing for certain metals in certain supplements, it actually doesn’t directly apply to people.

Sample size?

The researchers looked at 26 prenatal supplements they got from health food stores and pharmacies in Canada.

Prenatal vitamins were collected from assorted retail outlets including several health food stores, pharmacies, as well as food retailers within a large metropolitan city – Edmonton, Alberta, Canada. All available prenatal brands found were acquired and included – no brands were excluded. Altogether, 26 varieties of prenatal vitamins were collected, with 16 samples having more than one lot number to determine intra-product variances. 51 samples in total were sent for analysis to ALS Scandinavia labs. Some products only had one lot number in multiple locations throughout the metropolitan area, and thus we were only able to test one batch of these particular brands.

Correlation/Causation? Unsupported Conclusions?

You may have heard the term “correlation does not equal causation.” In a nutshell, this means just because we see something happening alongside something else doesn’t mean that one caused, or even influenced, the other. I dive into this is more detail in this post:

This study didn’t have any correlation/causation because it looked at amounts of certain metals in certain supplements. There is no indication whether they correlated/caused with any health outcomes at all. No people were included in the study.

This study didn't have any correlation/causation because it looked at amounts of certain metals in certain supplements. There is no indication whether they correlated/caused with any health outcomes at all. #toxic #vitamin #NHP Click To Tweet

What they did is compare the amounts of each toxic metal in the samples to the toxic limits for exposure:

There are established upper limits of ingestion on a daily basis of toxic elements from various organizations. However, few organizations have set limits for reproductive toxicity in relation to gestational and/or lactational exposure. The most stringent are from Proposition 65 in California and the US Pharmacopeia as listed in Table 1.

See Table 2 for the number of samples that ranked higher than the acceptable limits for each metal.

The good news is that when it came to mercury, cadmium, thallium, and nickel, none of them exceeded the acceptable limit. Three of the 26 had too much aluminum and arsenic. Fourteen had too much lead.

While these results are NOT cool (read: concerning), at this point we really don’t know that they’re associated with any health concerns at all so far.

I talked before about how some miniscule health risks and benefits are often blown out of proportion using the “coffee causes cancer” scare as an example.

The main concern from this study was lead, since it was found in every single sample. Lead is also found in food, water, and tea. Plus, it can bioaccumulate and affect exposed children’s behaviour and brain health.

There is a potential issue here.

Unreplicable results?

This is often yet to be seen. Whenever a new study is published, did it try to look at the results of a previous study in a different or new way? Or was it testing a brand new hypothesis?

Well, amounts of lead in US prenatal supplements was tested before:

These results are in keeping with previous results from the U. S. Food and Drug administration (USFDA) done in 2008 almost 10 years ago where average Pb levels in prenatal vitamins were 0.845 μgm/day.

In this case, these recent results are similar to results from 10 years ago, even though the amounts in this study are smaller (0.535 μgm/day).

In terms of other metals, we will have to see future research into the amounts of heavy metals found in supplements.


Where are these toxic heavy metals coming from?


In short, nobody knows:

…”there are myriad potential sources of toxic element contamination.”

Whether it’s from the raw materials themselves (active ingredients on inactive ingredients), the transportation, the manufacturing, etc. This is something that the manufacturers will have to each figure out for themselves.

Where are these toxic heavy metals found in prenatal supplements coming from? In short, nobody knows. #toxin #metals #supplements Click To Tweet


What to do?


Right now, we don’t know the whole picture, but here’s what’s recommended:

  • Pressure industry to improve their raw materials, processes, and quality control;
  • Pressure regulatory bodies to make this an issue;
  • For people who take them: Get enough essential minerals. Essential minerals can prevent the body from absorbing toxic heavy metals in the first place.

Likewise, adequate essential minerals will protect the body from absorbing toxic elements which are listed in descending order of importance in this protection: Se > Ca > Mg > Fe > Zn > Cu. All prenatal vitamins had some Ca, Mg, Fe, Zn, Cu, K, Na, and manganese. However some had negligible amounts. Four of the vitamins tested did not include Se, which is the most protective.

PRO TIP: Some of the least expensive products without any special claims had lower amounts of heavy metals than some with “organic,” “non-GMO,” or “pesticide-free” claims.

The cost range of the samples was quite substantial with the lowest cost tablet at $0.03/day to a high of $2.06/day. A cost/benefit analysis on these vitamins revealed no correlation between product cost and the level of contamination. Interestingly, however, the most expensive sample provided the highest levels of toxicants. Being labeled as non-GMO, organic or pesticide-free did not correlate with the level of toxic element contamination. The reality that some lower cost products are able to achieve less contamination suggests that safer products with less accrued toxic elements are possible to achieve.

Unfortunately, the researchers didn’t disclose which brands and products had which levels of which metals in them. I wonder if this was because of what happened to another researcher in the US recently:




Yep, it seems to be true that many prenatal supplements available in Canada have unacceptable levels of toxic heavy metals. We don’t know if this is linked at all to any health effects – more research will show.

More importantly, if you do see health headlines or studies, you can skeptically review them based on what you learned in this post.


Signing off and toasting: To skeptically and thoughtfully reviewing new studies!


Over to you

Did you hear about this study in the media or online? If so, add the link in the comments below and we can see how accurate it is. Do you think that pressuring industry and regulators for better quality supplements is the best strategy now?

I’d love to know (in the comments below)!



What’s the latest health research for your nutrition, fitness, or health coaching practice?

Find out in the weekly Health Scoop News 📑email updates. See some of the latest studies (with Leesa's "in other words" explainers) here. Sign up if you want to be first to know new research:

Done-for-you health articles

Featured products for your credible health blog:


202110 – Doom-scrolling tanks your mood

Pre-written mini-article to customize and share

Click here for preview

2021 Aug Longevity diet

Pre-written mini-article to customize and share

Click here for preview

Sustainable food article

3,494 words in 3 parts – 28 references

Click here for preview

I’m Leesa Klich, MSc., R.H.N.
Health writer – Blogging expert – Research nerd.

I help health and wellness professionals build their authority with scientific health content. They want to stand out in the crowded, often unqualified, market of entrepreneurs. I help them establish trust with their audiences, add credibility to their services, and save them a ton of time so they don’t have to do the research or writing themselves. To work with me, click here.

Leave a Reply

Your email address will not be published. Required fields are marked *