I’m not pro-supplements. I’m also not anti-supplements. I’m about being well-informed about supplements.
First, let’s define what we are talking about here, since “supplement” is used to refer to a grab bag of things.
For the purposes of this piece, I consider supplements to be any vitamin, mineral, herb, botanical extract, amino acid, enzyme, or microbial used for some supposed health benefit. For example:
Vitamins: Vitamin D, Vitamin B12, biotin, multivitamins (usually more appropriately called multivitamin/multiminerals), etc.
Minerals: Magnesium, calcium, iron, etc.
Herbs: Ashwagandha, turmeric, ginger, etc.
Botanical extracts: Berberine, green tea extract (EGCG), resveratrol, etc.
Amino acids: Creatine, L-carnitine, glycine, etc.
Enzymes: Digestive enzymes, lactase, CoQ10, etc.
Microbial: Probiotics, Prebiotics, Postbiotics
Supplement Safety
Supplement oversight is essentially nonexistent.
While medications are regulated by the FDA, food products are regulated by the USDA, and a handful of other regulatory bodies keep tabs on consumer and product safety, the supplement industry is like an unsupervised teenager seeing how far they can go.
The Dietary Supplement Health and Education Act of 1994 (DSHEA) established that supplements do not need approval for safety or effectiveness before going to market. It stipulates that the FDA only gets involved to determine if a supplement is unsafe after it’s already for sale. Note: the burden of proof is on the FDA…
What’s A Consumer to Do?
The lack of supplement safety oversight results in three main safety concerns:
Supplements may contain ingredients different from those listed on the label1
Supplements may contain contaminants2
Supplements may contain way more or way less of the stated active ingredient3
Looking for products that are third-party tested is currently the best way to choose safe supplements, including USP Verified, NSF, and ConsumerLab.
But, Wait! Too Good to be True?
While third-party organizations may test for safety and purity of supplements, they do not test to see if the supplement does what the company says it does.
This is important.
The only labeling requirement that DSHEA outlines is a phrase I’m almost certain you’ve seen if you’ve ever shopped for supplements:
This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
While this statement really says it all, it is like the fine print that no one reads, understands, or pays attention to.
Every bottle of supplements tells us that they aren’t regulated.
Every bottle of supplements states that they aren’t meant to prevent or treat disease.
But does that stop us from believing otherwise? No.
And that is because labels can say just about anything other than “diagnose”, “treat”, “cure”, or “prevent.”
A label can’t say “prevents osteoporosis,” but it can say “supports bone health.”
A label can’t say “treats diabetes,” but it can say “helps maintain blood sugar levels.”
A label can’t say “prevents heart disease,” but it can say “supports healthy cholesterol levels.”
The fact that these claims are misleading is not a consumer problem. It is marketing getting at the heart of our hopes, worries, and desire for health. Heck, some sound tempting to me sometimes, and I study this stuff!
Pros & Cons
Supplements aren’t all good or all bad. There are certainly circumstances where supplementation may be needed. Yet, it is always important to remember that supplements aren’t risk free.
Pros:
Nutrient deficiencies: The most common scenario in which I recommend supplementation is to address an identified nutrient deficiency. In fact, when it comes to vitamin & mineral supplementation, specifically, there doesn’t seem to be much benefit when there is no deficiency or insufficiency1.
Increased needs: Some people have increased needs for certain nutrients, which can be difficult to get through diet alone. During pregnancy, for example, research supports specific vitamin and mineral supplementation to protect the health of the mother and the growing baby.
Digestive challenges: We get nutrients into the parts of our body that need them through eating food. That food is then digested into small enough pieces to be absorbed into the bloodstream and distributed throughout our body. Several digestion and absorption challenges may make this process ineffective, and supplementation can sometimes be part of the intervention.
Inadequate intake: Whether because of necessary or chosen food restrictions (allergies, vegan, etc.), decreased appetite due to medication or illness, or even eating disorders, supplements can sometimes help fill nutrient intake gaps when food alone is not sufficient.
Cons:
Risk of toxicity: More is not better, especially for supplements whose excesses are stored in our tissues instead of being excreted. I see this most commonly for Vitamins A, D, E, and K, which are fat-soluble, meaning that they require fat to be absorbed as well as stored, which gives two important pieces of information:
First, if you are taking a Vitamin D supplement, for example, you will absorb it more readily if you take it with a meal containing at least a little bit of healthy fat.
Second, if you overdo that Vitamin D supplement, excess will be stored in body fat, increasing the risk of Vitamin D toxicity. More is not better.
Supplement interactions: Supplements are not benign. Even if you take a supplement because you need it and you choose a product that has been third-party tested, interactions between individual supplements and between supplements and medications are common, ex:
Supplement<>Supplement: Calcium blocks iron absorption, so taking both in supplement form at the same time reduces the amount of iron that gets into your body.
Supplement<>Medication: St. John’s Wort famously interferes with some birth control pills, making them less effective, and interacts with common antidepressant (SSRI) medications.
Mask other deficiencies: Blindly taking supplements because you’ve heard they are healthy may mask a true deficiency, which can be incredibly dangerous. Taking folate or folic acid without monitoring, for example, may disguise a Vitamin B12 deficiency, which is associated with cognitive decline.
Contamination risk: There is no pre-market regulation for supplement safety. This means that supplements may or may not have the ingredient(s) listed on the label, may have more or less than the amount on the label, and/or may have contaminants such as lead. Third-party testing is the best way to evaluate each of these risks.
False sense of security: You can’t out-supplement a low-quality diet. Too often I see people who are spending loads of money on supplements only to be eating fast food, highly processed snacks, and other low nutrient quality foods. In this case, it is often best to save the money you spent on supplements to buy higher-quality food.
Cost: The supplement industry is valued at $70 billion in the US alone, with the average US adult spending more than $500 a year on various supplements, with some spending way more. I’m not saying some supplements aren’t worth it, but being well-informed about supplements can protect your health and your bank account.
Are Supplements Right for You?
There are so many factors that go into deciding if a supplement is right for you. Below is the process I use when working with patients to decide if they may need to supplement, how much they may need, and for how long they may need it.
1. Test, Don’t Guess
I don’t use the “throw spaghetti at the wall” approach for supplements. Everyone has different needs, and taking something that you don’t need isn’t harmless.
Yes, Vitamin D, B12, and iron are important for all of us. But it doesn’t mean we all need to take them in pill form. Remember, supplements… supplement. We don’t need to fill a gap if there isn’t one.
Testing the status of vitamins and minerals in your body first to determine if a supplement is even needed is the place to start.
Now, it isn’t realistic to test the status of every vitamin and mineral. Nor would your doctor likely write that order. To figure out what nutrients to check, it is helpful to understand your risk:
Dietary patterns at most risk of inadequate micronutrient intake:
Vegan: Vitamin B12, Vitamin D, Omega-3s, Iron, Zinc, Iodine, Calcium4
Vegetarian (eats dairy/eggs): Vitamin B12, Iron, Vitamin D, Omega-3s
Bariatric surgery post-op (ex: gastric bypass, gastric sleeve): Vitamin B12, Iron, Calcium, Folate, Thiamine (B1), Vitamins A, D, E, K
Life stages at most risk of inadequate micronutrient levels:
Older Adults:Vitamin B12, Vitamin D, Calcium
Pregnant/Breastfeeding: Folate, Iron, Iodine, Choline, Omega-3
Heavy Menstruation: Iron
Medical & lifestyle factors at most risk of inadequate micronutrient levels:
Limited sun exposure, darker skin: Vitamin D
Digestive conditions (Crohn’s, Ulcerative colitis, celiac): Vitamin B12, Iron, Folate, Vitamins A, D, E, & K
Excessive Alcohol Intake: Thiamine (B1), Folate, Vitamin B6, Magnesium
Smokers: Vitamin C
Certain medications:
Metformin: Vitamin B12
Stomach acid reducers (ex: omeprazole/Prilosec, famotidine/Pepcid): Vitamin B12, Magnesium, Calcium
Diuretics: Potassium, Magnesium
2. The Limits of “Within Normal Limits”
Pet peeve time.
Just about everyone has access to their lab results and can quickly scan them for anything outside the “green” range, which indicates the “normal” reference range.
How handy. So what’s the problem?
Most reference ranges aren’t standardized.
Reference ranges are typically set by the lab or lab equipment company.
Reference group populations vary.
“Normal” shows what is common in a reference group, not necessarily what is ideal for you.
All of this means that simply looking for values that are either in or out of range can mislead you — a value outside the range can cause undue concern, and a value within a given range can create a false sense of security.
Interpreting lab results involves appreciating the context of age, medical history, symptoms, genetics, goals, and more.
A deficiency is defined as a nutrient level outside the reference range and likely to cause signs and symptoms in most individuals.
An insufficiency/inadequacy is suboptimal nutrient status typically at the low end of a reference range, which may cause signs and symptoms in some individuals.
Both can cause symptoms. But it takes more than being in or out of the reference range to appreciate that.
I recently experienced a perfect example of this. I was feeling more fatigued and just not feeling like me. So I asked my doctor to test for anemia and low iron stores (more about how they differ here).
The most sensitive marker of iron stores, ferritin, was just inside the green reference range:
But wait, do you see that reference range? It is almost too large to make it meaningful.
So I didn’t have iron-deficiency anemia.
I didn’t have iron-deficiency without anemia, either.
But with my symptoms and my unique history, my doctor agreed that I had insufficient iron levels and an agreed-upon supplementation regimen was started.
3. “More” ≠ better
If you do need to supplement, don’t reach for the biggest dose you can find. Not only can your body not always absorb larger doses, but it may also cause side effects and even toxicity.
Let’s go back to my iron example. We now know that iron supplements are most effective and have the least side effects when taken every other day.5 More is not better.
Just because you can buy a 10,000IU Vitamin D3 supplement (typical doses are 2,000-4,000IU per day) or a 20mg melatonin supplement (I don’t typically recommend more than 5mg), doesn’t mean you should.
Please, please, please ask the questions to make sure you are supplementing only what you need and no more.
4. Happily Ever After?
The story does not end here. Periodically retesting nutrient status can let you know whether the amount you are taking is effective, the dose needs to be adjusted, or it can be stopped altogether.
While those following a vegan dietary pattern or who had bariatric surgery will likely need some level of supplement indefinitely, testing at least annually is recommended.
Many other supplements can be decreased or discontinued after a period of time, especially if the reason for the deficiency or insufficiency has been resolved.
In my case, my ferritin levels came back up nicely, but since I don’t eat red meat and I have other risk factors for iron insufficiency, I will continue to work with my doctor to create a plan to take my supplement less often and check my levels periodically.
Thanks for being here,
~Allison
Please remember that this information is meant to educate and inspire but is not medical advice - please consult your healthcare team to determine what is most appropriate for you.
Ex: A study published in BMC Medicine tested 44 herbal supplements from 12 companies and found only 48% actually contained the plant species listed on the label; a third contained undisclosed fillers or contaminants, some with known toxicity.
https://nutrola.app/en/blog/can-you-trust-supplement-labels-fda-testing-reality
Ex: Ashwagandha, rhodiola, ginseng, and schisandra supplements were found to have widespread lead and nickel contamination, with lead exceeding safe limits by up to 235% and nickel by up to 321% in some products. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12650394/
Ex: A study testing 55 bottles of over-the-counter vitamin D from 12 manufacturers found potency ranging from just 9% to 146% of the labeled amount. https://www.managedhealthcareexecutive.com/view/vitamin-d-potency-varies-widely-dietary-supplements
Calcium is unique in that blood tests can't reliably assess intake adequacy. This is because the body may pull calcium from bones to keep blood levels stable, raising the risk of bone loss. Those at high risk of inadequate intake should work with a dietitian and ask their doctor about bone mineral density testing.
This is because iron receptors get saturated, meaning that even if taken daily, your body can’t really do anything with it, so it travels through your digestive system, which can potentially wreak havoc on your bowels.