Are the Supplements You're Taking Safe?
There's a LOT of crap out there people ... choose wisely!
I was working on a handout about sleep supplements for my recent Sleep Reset program, including a section on supplement safety. I was sharing some of my in-progress findings with a couple friends, and they were stunned at the adulteration and poor quality of the supplements.
So, here we are.
About the FDA
First thing’s first: The FDA does not review or approve supplements, which means if a supplement claims to be FDA-approved, it’s a lie; it also means even some hormones, like melatonin, can be sold without much regulation. In fact, for some supplements, the FDA doesn’t even need to be aware they’ve been launched into the market (1). Unless a dietary ingredient is considered a “new ingredient” or certain marketing claims are made, FDA notification is unnecessary (2,3).
The FDA will take actions against supplement manufacturers when there is sufficient evidence that they cause harm and/or when there is evidence that Current Good Manufacturing Practices (CGMP) were violated (4). Quite often, the first (and only) course of action against a supplement manufacturer is via a Warning Letter; supplement makers receive a Warning Letter when they violate CGMP, make inaccurate or inappropriate claims, or incorrect directions for use (5).
The FDA provides guidance on what is considered a dietary ingredient that can be included in dietary supplements, which includes:
The term "dietary ingredient" includes vitamins and minerals; herbs and other botanicals; amino acids; "dietary substances" that are part of the food supply, such as enzymes and live microbials (commonly referred to as "probiotics"); and concentrates, metabolites, constituents, extracts, or combinations of any dietary ingredient from the preceding categories.
There are two types of ingredients that may be used in dietary supplements: “dietary ingredients,” discussed above, and “other ingredients.” These “other ingredients” include substances such as fillers, binders, excipients, preservatives, sweeteners, and flavorings. (6)
Aside from that definition, the following language is pretty much all the FDA provides by way of guidance:
Manufacturers and distributors of dietary supplements and dietary ingredients are prohibited from marketing products that are adulterated or misbranded. That means that these firms are responsible for evaluating the safety and labeling of their products before marketing to ensure that they meet all the requirements of the Federal Food, Drug, and Cosmetic Act as amended by DSHEA and FDA regulations (7).
If that seems rather loose and vague to you, it is.
For the record, though, food chemicals and additives have different requirements and undergo post-market assessment. Marketing and advertising claims made about food (for example if something is a good source of fiber or low in sodium) are also subject to scrutiny. The FDA also reviews and approves pharmaceutical drugs and over-the-counter medications (which are considered drugs). Per their name, they quite literally only review food and drugs … supplements are part of neither category.
The supplement industry is projected to be a $300B industry by 2028 (8). With relatively loose requirements and enforcement, it leaves a lot of room for poor quality, ingredient variation, and lack of testing.
Let’s take a look at a few examples.
Melatonin
Melatonin is a hormone that is necessary for sleep and sleep-wake cycles.
A 2023 study showed that melatonin gummies across 30 brands contained between 74% to an astounding 347% of the quantity of melatonin on the label (9).
A 2017 study found that melatonin (powdered and liquid) across 30 brands had between 83% and 478% (YIKES!) of the amount of melatonin noted on the label; 70% of the supplements had a concentration less than 10% of what was claimed (10).
Disturbingly, many of the supplements included additives like significant amounts of serotonin (highly problematic!) as well as typical fillers like silica, cellulose or rice powder (10).
Most western countries don’t even allow OTC purchase of melatonin; they require a prescription.
Thyroid Supplements
Often, people who experience symptoms attributed to hypothyroid—whether they have subclinical or frank hypothyroidism—seek out supplements that claim to help improve thyroid function.
In a 2013 study (waaaay back in 2013!), researchers bought 10 thyroid supplements online and in stores; 5 of them were herbal supplements and 5 were advertised as containing bovine thyroid raw tissue or powder. Based on the melatonin study above, want to take a guess at the results?
Half of the products contained actual T4 hormones at levels ranging from <0.5 to 22.9 mcg per tablet—up to 22.9 mcg per tablet (11)! Nine out of the 10 products contained actual T3 hormones ranging from 1.3 to 25.4 mcg per tablet (11). Nine out of 10, people. That is incredibly bad, misleading and dangerous. And, that means that at least 4 of the products contained both T3 and T4 hormones at significant levels (11). Keep in mind that several of these products called for taking more than one tablet or capsule per day—one of the herbal supplements called for taking 4 capsules per day, which would have someone taking 92 mcg of T4 and 17 mcg of T3 per day (11) … for context that’s more than I take of my actual prescription thyroid medication, and I only have ⅓ of my thyroid!
This means people who have a healthy thyroid and/or are taking prescription thyroid medication are severely over-supplemented and are likely experiencing some potentially severe hyperthyroid symptoms and, in some cases, thyrotoxicosis requiring hospitalization. The right balance of thyroid hormones is critical; this is definitely not one of those “if some is good, more must be better” situations.
Some individuals may look to these supplements for a more natural way to improve their thyroid function, but they don’t realize they are actually consuming thyroid hormones at unpredictable levels.
Thyroid supplements aren’t the only place thyroid hormones show up in supplements, either. A 2017 research study examined 29 weight loss products and found 31% of them contained thyroid hormones (either T3, T4, or both) (12). Thankfully, these researchers found that the amounts of thyroid hormones in the weight loss supplements were not clinically significant in most cases. However, there have been a number of case reports about patients with thyrotoxicosis from diet pills reporting to emergency rooms with symptoms that include being delirious, unaware of the date or location, rapid heart rate, tremors, and others (13).
For the record, while melatonin is an acceptable dietary ingredient for a supplement according to the FDA, anything that requires a prescription (like thyroid hormones) is not deemed acceptable for over-the-counter purchase and should not appear in dietary supplements. So, it doesn’t matter how little of an amount of thyroid hormone that may have been found in any of these supplements (even if the researchers call it “negligible”). Whether for thyroid health support or weight loss, any amount is a violation of FDA guidelines (read: illegal and inappropriate).
Making Informed, Safe Decisions
So, now you might be wondering how to make sure you don’t end up ingesting something that may do more harm than good.
It sounds like a real pain in the ass, but it is on you to do the due diligence, so, first and foremost: Do your research.
Don’t simply rely on Amazon and Amazon reviews. Go to a company’s website, look for their quality control and quality assurance processes.
Things to look for:
Identify how they obtain and source their ingredients. Do they grow herbs themselves? Do they source internationally? If they source internationally, do they speak, at all, to how they choose their sourcing partners? How do they ensure those sourcing partners aren’t using hazardous or harmful materials and/or maintain safety standards?
Check to see if they follow CGMP guidelines
Check if they have their raw materials third-party lab tested; do they batch test every batch or only randomly selected one?
Do they obtain certificates of authenticity for ingredients they acquire outside of the U.S.? This applies especially if they make claims that something is organic and sourced in other countries … what are those standards for ensuring it's organic? Are there guidelines or is it simply marketing? They will likely not be willing to share their certificates with the public, but do they claim to obtain them anywhere on their website?
Are they willing to share materials safety data sheets? Very rarely a business will include these on their websites, more commonly, you’ll have to submit a request for one
Go to the FDA Warning Letter website and see if they’ve received a Warning Letter (or worse) and how the elements called out in the Warning Letter were addressed, if at all. Also, don’t be afraid to report a supplement company if you experience adverse reactions that aren’t related to a frank allergy on your part.
Remember that it is illegal for a supplement company to include pharmaceutical and illicit drugs or medications in any supplement. It’s also illegal for them to include any additional substances (whether OTC drug, other drug, or other ingredients) and not have it properly represented in the ingredients list.
Use the National Institutes of Health Dietary Supplement Fact Sheets and Botanical Supplement Fact Sheets to learn about specific ingredients and how they may affect your health. Note that if you’re working with a qualified health professional, they may recommend amounts that are higher than recommended dietary allowance (RDA) and daily adequate intake (AI) amounts. Daily recommended doses are designed to ensure you get the minimum amount needed to avoid frank nutrient deficiency; they do not necessarily address subclinical nutrient deficiencies or your specific health needs. Therapeutic levels may vary greatly from daily recommended doses or upper limits; however, they should not generally be maintained for long periods of time.
Always check with your healthcare provider if you have questions about whether a supplement is right for you.
Check interactions and side effects. Keep in mind that most supplements and medications come with side effects; be sure to do your research and understand what the side effects are—especially if you’re taking multiple medications. The Medscape Drug Interaction Checker is a good place to start; you can check drugs, over-the-counter recommendations, and herbal supplements. I also personally use the Epocrates app (it’s free!) to check for drug indication, contraindications, side effects, etc.
None of the information above should be constituted as medical advice, supplement advice or recommendations, or treatment advice. It is your responsibility to do your due diligence to ensure the supplements you take are safe, appropriate for you, your health, and your medications/supplements. Consult appropriately with your healthcare provider.
References
(1) Information for Consumers on Using Dietary Supplements
(2) How to Submit Notifications for a New Dietary Ingredient
(3) Notifications for Structure/Function and Related Claims in Dietary Supplement Labeling
(4) Warning Letters
(5) About Warning and Close-Out Letters
(6) Questions and Answers on Dietary Supplements
(9) Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US
(10) Poor Quality Control of Over-the-Counter Melatonin: What They Say Is Often Not What You Get
(11) Thyroid Health Supplements Contain Significant Amounts of Thyroid Hormones
(12) Negligible Thyroid Hormone Content Present in Nonprescription U.S. Weight Loss Products
(13) Thyrotoxicosis After Consumption of Dietary Supplements Purchased Through the Internet