What's In Your Prenatal Vitamin?

It's shockingly hard to tell

The U.S. Government Accountability Office (GAO) recently published a report on prenatal vitamins, comparing the ingredients listed on the label with what was found when the supplements were tested, as well as testing for potentially harmful contaminants. This kind of work is necessary because individuals who are trying to conceive, are pregnant, or breastfeeding need to know if prenatal vitamins contain what they claim so they can be assured they are getting the expected health benefits from these products. In addition, there have been reports of contamination of prenatal vitamins with heavy metals and fungi, but we don’t have a good idea about the scope of the problem. For example, in a study published in 2018 from Canada, 51 prenatal vitamins from 26 brands were tested, and 20 samples exceeded the threshold for lead, which they set at 0.5 mcg/day (this is the level from Proposition 65 in California). Yes, 40% of the samples. One product had 4.0 mcg Three samples had toxic levels of thallium, and three had levels of inorganic arsenic over the accepted safe range! In 2021, Spotlight on America tested over 220 prenatal vitamins, and 25 exceeded the 0.5 mcg/day Prop 65 limit for lead.

And to the Canadians who keep insisting the supply of supplements is safer in Canada, the products in the Canadian study were all bought from brick and mortar stores in Edmonton.

The Report From the GAO

Twelve types of prenatal supplements (four gummies, four soft gels, and four tablets) were tested for six key nutrients listed on their labels. Three doses of each product were tested. Folic acid, iodine, and iron were selected because they are recommended for their health benefits in pregnancy. Vitamin A, Vitamin C, and Vitamin E were selected because while small doses are recommended, high doses in pregnancy could be harmful. The study examined whether these ingredients were present in the acceptable range set out by the U.S. Pharmacopeia (USP) and/or whether the product contained more than the tolerable upper limit. USP guidelines refer to acceptable manufacturing practices. For example, according to USP guidelines, it is acceptable for a product with vitamin A to contain anywhere from 100% to 165% of the stated label for a tablet or softgel. Tolerable safe limits are a level that could be concerning to your health. 

Important side note. Two of the twelve (products F and I) contained methylfolate, not folic acid, so they were tested for methylfolate. However, the report lists all results as folic acid. I emailed Karen L. Howard, Ph.D., the Director of Science and Technology Assessment at the U.S. Government Accountability Office, for clarity. She explained that while the results for the methylfolate-containing supplements say a percentage for folic acid, that was for simplicity’s sake in the reporting; the results should be interpreted as a percentage of methylfolate on the label.

The report also evaluated the presence of four heavy metals, lead, arsenic, cadmium, and mercury, as they are associated with harmful effects on fetal development. 

Here is a graphic from the reports showing the levels of nutrients in the key supplements; I have modified it so you can see which supplements had methylfolate.

Here are some key findings:

• Only one product, a prenatal gummy, contained everything it claimed within the accepted deviation from the amounts on the label. It did not have iron, as gummies don’t typically contain iron due to the difficulties in manufacturing it in that form. 

• A total of six prenatal vitamins didn’t contain enough folic acid, four because they had less folic acid than stated on the product label, and two had none because they had methylfolate. One of the supplements with folic acid had 50% less of what the label stated it should contain. The consequence here is some prenatal vitamins are not delivering enough folic acid to reduce the risk of neural tube defects. 

• All the supplements with iron contained iron in the acceptable range. 

• The amount of vitamin E in the supplements ranged from 28 to 332% of what the labels claimed, and four products had vitamin E that exceeded the USP range. High doses of vitamin E  are associated with pregnancy complications, including fetal loss or neonatal death.

• Vitamin A was the nutrient that was most frequently outside the USP standard, with nine of the 12 products or a staggering 75! Fortunately, most had too little as opposed to too much. Still, two products had more vitamin A, and this is always a potential concern as 1,300 mcg of RAE (retinol activity ingredients) is recommended in a prenatal supplement. The tolerable upper limit is 3,000 mg RAE daily; one product tested was slightly over this value. Doses of > 7,500 mg RAE of vitamin A within 60 days of conception are associated with miscarriage and spontaneous abortion, so good manufacturing practices here are essential.

• No products had concerning levels of lead, arsenic, or cadmium and the amount of lead conformed to the Prop 65 standard of less than 0.5 mcg per day. This was a small sampling, so we don’t know if the situation would be better or worse if more doses from more batches were tested.

We don’t know the reason for the variability in the products. Vitamins are apparently hard to make in a shelf-stable way, and so this is one possibility, but this is no excuse. It is a reason to turn some of the massive amounts of profits from making vitamins into research and development to correct this problem. Without legislation, this is unlikely to happen. Science can often solve these manufacturing issues, but sometimes, it can take decades of research. Look, it used to be impossible to give progesterone orally because of absorption issues, and then, through research and development, scientists figured it out, and now we have oral progesterone. But the drive to do this came from Pharma, and they had to prove they did what they claimed to the FDA. Many topical progesterone supplements that can't be absorbed and are scams are sold as supplements, which is the difference between oversight and no oversight.

Heavy metals, which do show up in some studies but didn’t here, can come from a variety of sources. While contamination during manufacturing or even purposeful addition (like with Ayurvedic medicines) can be one source, it can also be from bioaccumulation; basically, the heavy metals build up in the raw product that is used to make the supplement. For example, the natural sources used for some calcium supplements include shells, bones, and rock, which can be a lead source. This is no excuse; companies can and should test their products and look for sources with lower risks of lead contamination. 

The GAO doesn’t release the names of products, so I can’t tell you which products had too little folic acid or the one with the highest vitamin A level. I asked Dr. Karen Howard from the GAO if any of the products had third-party testing verification labels to see if that was predictive of label accuracy. This is what she told me:

According to our analysis, third-party verification is not a guarantee of conformity to the amounts on the label. Five of the 12 prenatal supplement products we tested stated on their labels that they had undergone some form of third-party verification. We found that, on average, these five verified products performed similarly to the non-verified products, although none of the products with third-party verification had nutrient levels present in amounts that may cause a health concern.

Sigh. 

More About Third Parties…

I decided to take a peek at ConsumerLabs.com and Consumer Reports to see what they recommended regarding prenatal vitamins…and I received a couple of shocks. 

ConsumerLabs.com mentioned that 29% of multivitamins tested had labeling inaccuracies. Their top pick for prenatal vitamins is MegaFood Baby & Me 2. HOWEVER, which is in capital letters for a reason: MegaFood Baby & Me 2 has 612 mg of L-5-methyltetrahydrofolate, NOT folic acid. I was shocked, as only folic acid is recommended by the CDC to prevent neural tube defects. You can read more about the different types of folate and why folic acid is recommended here. 

I contacted ConsumerLabs.com and asked why they recommended a product without folic acid. I received a reply from Dr. Cooperman, the President and Founder, who told me via email that the National Academies recommend “that pregnant women get 600 mcg DFE (dietary folate equivalents) daily from supplemental folate, which would mean either folic acid or another synthetic form, such as methylfolate,” and that "600 mcg DFE (dietary folate equivalents) is equal to about 360 mcg of folic acid or methylfolate.”

In my email, I mentioned that the CDC and ACOG recommend folic acid, and his response:  

“It may be that the organizations you mention focus on "folic acid," as there is more research on folic acid than with methylfolate. We are agnostic as to the synthetic form -- MegaFood happened to use methylfolate rather than folic acid. There is, however, a potential advantage to methylfolate over folic acid, in that a small percentage of the population may, due to genetics, be less able to utilize folic acid than methylfolate -- although any real advantage has yet to be proven. We liked MegaFood mainly due to other features, such as providing a significant amount of choline.”

This was disappointing. You know who isn’t agnostic about folic acid vs methylfolate or other non folic acid forms of folate? The experts at the Centers for Disease Control and Prevention and the American College of Obstetricians and Gynecologists. This is because we have clinical trials showing folic acid reduces neural tube defects, and there are no clinical trials showing that non folic acid forms of folate in supplements, like methylfolate, reduce neural tube defects. This means that people taking a supplement with a form of folate other than folic acid cannot be sure they are getting the needed benefit. There is no upside, with a big potential downside. Why should you, the consumer, bear the risk with an untested form of folate when a tested and safe form is available? 

The evidence also does not support the claim that people with an MTHFR genetic variation do better with methylfolate. The experts at the CDC say that people with an MTHFR variation can get all the folate they need from folic acid. 

When I asked Dr. Shannon Clark, a board-certified OB/GYN and maternal-fetal medicine specialist about the recommendation from Consumerlabs.com, she replied, 

Folic acid is the only form of folate found in prenatals/supplements that has been proven through numerous studies, including RTCs to help prevent against neural tube defects in the fetus, some of which are lethal. While these companies try to say methylfolate is better or equivalent to folic acid, we don’t know this to be true.

Dr. Clark recommends that consumers “make sure the nutrition and supplements facts label specifically says “folic acid” followed by the amount of micrograms.”

Next, I went to Consumer Reports, which did not report safety testing but had lists of prenatal supplements based on their labeling. I was shocked to see that many products, like Ritual and Pink Stork Prenatal, were recommended even though they do not contain folic acid but rather one of the other folates. Even worse, these non-folic acid-containing products were labeled by Consumer Reports as containing folic acid! The language about folate is confusing, so absolute clarity is essential.

See a screenshot from Consumer Reports below to the left and the Pink Stork product label to the right.

I emailed Consumer Reports.com and sent them the information from the CDC, and I am pleased to say that they were very responsive and, after reviewing the data, amended their page and now clearly state which prenatal vitamins contain folic acid and which do not! Click here to see the list.

An updated screenshot from Consumer Reports.

They also added this nice comment at the end of their report. 

What Can You Do?

Some supplements are needed, and prenatal vitamins are one of the best examples. Unfortunately, they are also a great example of why products need to be tested and safe because pregnant people shouldn’t have to play folic acid, vitamin, and heavy metal roulette. We need more studies to understand how common contamination is with these products and how often they deviate from the amounts listed on the labels. 

This system of relying on third-party testing also needs further exploration. The GAO did not tell me which third-party testing labels were included on the products tested or how much they deviated, so it’s impossible to say more. I would still choose a supplement with one of the most known third-party testers, Pharmacopeia Convention (USP, label should say USP verified), NSF International, and ConsumerLabs, although I think the GAO should let the public know which products were verified and by whom. I am also disappointed in ConsumerLab's position on folic acid, as this is not supported by the relevant experts.

If you want to know which prenatal vitamins Dr. Clark, who is an expert, recommends, go to her Instagram. You can find her here. 

I have no grand words or a neat summary here. Regarding supplements, unfettered capitalism is the opposite of consumer protection (probably for all of medicine, for that matter). I’ll end with the summary from the GAO, and if this bothers you as much as it bothers me, call your Representative and Senator. Dietary supplements need oversight. You have the right to know what you are putting in your body.

References

1. FIGO Toxic Chemicals and Environmental Contaminants in Prenatal Vitamins. https://www.figo.org/resources/figo-statements/toxic-chemicals-and-environmental-contaminants-prenatal-vitamins

2. Prenatal Supplements; Amount of Some Key Nutrients Different from Product Labels. GAO-24-106689  Q&A Report to the Chair, Subcommittee on Human Rights and the Law, Committee on the Judiciary, U.S.Senate. Dec 12, 2023. https://www.gao.gov/assets/d24106689.pdf

3. Schwalfenberg G, Rodushkin I, Genuis SJ. Heavy metal contamination of prenatal vitamins. Toxicol Rep. 2018 Mar 6;5:390-395. doi: 10.1016/j.toxrep.2018.02.015.

4. CDC MTHFR Gene, Folic Acid, and Preventing Neural Tube Defects. https://www.cdc.gov/ncbddd/folicacid/mthfr-gene-and-folic-acid.html

5. Bourgoin BP, Evans DR, Cornett JR, Longard SM, Quattrone AJ. Lead Content in 70 Brands of Dietary Calcium Supplements. Am J Pub Health 1993;83:1155-1160.

6. Lashbrook A. How to Choose a Prenatal Vitamin, Consumer Reports 2023, April https://www.consumerreports.org/health/supplements/how-to-choose-a-prenatal-vitamin-a1197384921/ 

7. Multivitamin and Multimineral Supplements Review ConsumerLabs.com https://www.consumerlab.com/reviews/multivitamin-review-comparisons/multivitamins/#results