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The Truth About Nutritional Supplements: Making Informed Choices

A bottle of mismatched colorful pills pours out onto a white countertop

In an ideal world, we'd get all our essential vitamins and minerals from the foods we eat. However, reality can be far from this perfect ideal. The busy modern lifestyle can make it challenging to ensure our diets are broad & fresh enough to have all the micronutrients we need; only 1 in 10 Americans eats the recommended daily amount of fruits and vegetables. And even if we are getting the recommended daily amounts of fruits and vegetables, the unfortunate facts point to a global depletion of nutrients that can be found in food. 

“The nutritional values of some popular vegetables, from asparagus to spinach, have dropped significantly since 1950. A 2004 US study found important nutrients in some garden crops are up to 38% lower than there were at the middle of the 20th Century. On average, across the 43 vegetables analysed, calcium content declined 16%, iron by 15% and phosphorus by 9%. The vitamins riboflavin and ascorbic acid both dropped significantly, while there were slight declines in protein levels.” -How Modern Food Can Regain Its Nutrients

In addition to these dietary challenges that most of us face in getting our daily micronutrients, there are particular groups of people more at-risk for nutritional deficiencies and who could therefore benefit from supplementation:

  • People trying to achieve pregnancy or who are pregnant or lactating

  • People with a long history of oral contraceptive use

  • People taking pharmaceuticals that are known to deplete mineral and vitamin stores or disrupt their absorption (“Drug Muggers”)

  • People with digestion & absorption challenges, whether these are functional disorders like IBS or structural diseases like Crohns or Ulcerative Colitis

But before you rush to the nearest supplement aisle, it's crucial to understand the nuances of quality, quantity, and safety in the world of micronutrient supplementation. 

More Isn’t Always Better

Something that I do like to point out to folks is that there is such a thing as too much for many vitamins and minerals. Most micronutrients have an “tolerable upper intake level” beyond which they are more likely to cause adverse health effects. When patients come to me taking a laundry list of herbal supplements and vitamins, I’m careful to comb through them, both for quality and quantity. 

For example, one of my friends in primary care recently shared that she’s seen patients overdoing it with zinc over the last few years. Many people have been taking boatloads of zinc with the intention of boosting their immune systems. Too much zinc can deplete copper stores in the body, and copper deficiency can generate a host of systemic issues like anemia, cardiac arrhythmias, and osteoporosis. 

Let's take for example someone who takes a multivitamin, which often contains 136% of the Recommended Dietary Allowance (RDA) of Zinc. They eat plenty of foods rich in zinc like beef, pork, cashews, pumpkin seeds, and fortified cereal. And because they live with young kids who are seemingly always sick, they add on a daily Zinc supplement. In one brand I looked at, a single pill provided 237% of the RDA. In a day, this person has quickly racked up more than 400% of their recommended Zinc intake– and that’s all it takes to exceed the “tolerable upper intake level” of Zinc.

Quality Matters

Beyond quantity, ensuring the quality of supplements is paramount. Unfortunately, the supplement market is inundated with products of varying standards. The FDA does not regulate supplements for quality and efficacy, leaving consumers vulnerable to mislabeling and contamination. A recent study found that a staggering 89% of sports supplements tested did not accurately list their ingredients. Another study found that in Saffron supplements, “No saffron compounds were found in 16 (55%) of [products tested].”

There are two questions at the heart of the quality matter: label accuracy & purity. Does the label accurately reflect the amounts of micronutrients inside the product? And has the product been tested for contaminants like heavy metals, pesticides, molds, or other toxins? 

When assessing the quality of a supplement, I look for third-party certifications from reputable organizations like, NSF International, and US Pharmacopeia. These organizations have rigorous testing standards that provide a level of assurance regarding a product's quality and purity. These certifications come at a cost to the supplement companies pursuing the certificate, making them less accessible to smaller businesses; this presents an ethical challenge for those of us interested in shopping small, watching our eco-footprint & avoiding supporting international conglomerates. For me, the safety and peace of mind of this trade off is worth it.

How do I know which supplements I need?

A high-quality, broad spectrum multivitamin may be beneficial to most folks– and would be highly recommended for the list of specific populations mentioned in the intro . People with endometriosis, heavy periods, iron-deficiency anemia, or those looking to achieve pregnancy may be best supported specifically by a prenatal multivitamin. 

Beyond that, single-ingredient supplements might be appropriate for people on a case-by-case basis. I ask a number of questions when I work with patients before recommending any specific supplements. First, I want to see their lab work. Some basic blood work values may be “within normal limits” but trend toward the low or high end of the window; these can be clues for micronutrient deficiencies. We also undertake a thorough review of symptoms, general systems health, and familial health history. Finally, I’ll check out the pharmaceuticals they take for any known micronutrient interactions; some types of over-the-counter and prescription medications are known to deplete specific nutrients, vitamins, and minerals or block their absorption in the digestive system.


While supplements can play a vital role in supporting overall health, they are not a one-size-fits-all solution. Understanding the factors influencing individual nutritional needs and selecting high-quality supplements are essential steps in maximizing their benefits while minimizing risks. In the ever-expanding landscape of wellness products, informed consumers armed with knowledge and discernment can navigate the micronutrient maze with confidence and clarity.

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