Dietary Supplements by Dr. Stephanie Karozos, MD

Nearly 80% of US adults are taking one or more dietary supplements. From single herb supplements to blends to multivitamins, there are so many options that it can feel overwhelming at times. Supplements can be useful to both prevent and help treat a number of health conditions. Because supplements are not as tightly regulated as pharmaceuticals, there are many different brands at many different price ranges selling a whole host of products. It’s hard to know which pricier supplements are worth the cost, and which lower-priced brands are acceptable from a quality perspective. My hope is that this post makes it easier to quickly discern which supplements are high quality, knowing that you’ve made a worthwhile investment in your health and wellbeing.


Looking for the following labels can help to guide you in your supplement purchasing. I personally always look for GMP, NSF, or USP labels when I am purchasing a supplement, unless the company is otherwise extremely transparent about their quality control measures and product monitoring. There are some companies who bypass the need for these labels by having excellent internal quality monitoring processes. These are relatively uncommon, so look for a label unless otherwise instructed by a knowledgeable professional.


Products certified by NSF are audited at least twice a year to verify that the contents contained in the supplement match the label. NSF assesses for contaminants and ingredients that are not listed on the label. In the 90s, ephedra was being added to diet supplements without being transparent on the label. This carries serious health risks. It’s easy to understand why, with very little federal oversight of health supplements, third party testing is essential for quality assurance. NSF audits whole manufacturers, and every batch is tested. If a product carries an NSF label, you can be sure that the entire brand has been NSF certified.


Specific products can be USP certified, meaning that it has been verified for quality, potency, identity of ingredients, absence of heavy metals, and consistency from one batch to the next. This is not for entire brands, just specific products within a brand, so one product being USP labeled does not mean that all products within that brand are USP labeled.


This indicates that a company meets basic good manufacturing practices. An assessment of facility conditions, supplement quality (potency matching label, purity of ingredients and lack of contaminants), a CGMP label is a little more nebulous than NSF or USP labels but still can provide reassurance that quality was assessed formally prior to the supplement hitting the shelves.

USDA Organic:

The Dietary Supplement Health and Education Act does not have stringent requirements regarding pesticides in supplements. Because of this, looking for the USDA Organic label can be useful. This label signifies that the product must be at least 95% certified organic.

Other considerations

Consumer Lab:

Consumer Lab is a subscription-based company that offers independent third party supplement testing. For a nominal monthly fee, you can access their assessments of thousands of products.


Probiotics are rising in popularity. Refrigerating probiotics, while not always necessary, can help to prevent the helpful bacteria from dying off and becoming therapeutically inactive. Refrigerating fish oils and other omega 3s can help prevent rancidity.


Oftentimes, we find ourselves taking multiple supplements for various reasons. Most supplements do not need to be taken indefinitely, and many multivitamins, herbal blends, and problem-specific (i.e. blood sugar control) supplements have redundant ingredients from one product to the next. It’s always a good idea to take your supplements to a trusted health professional who can review them for quality and eliminate redundancy. I thoroughly enjoy when a patient brings in a bag full of supplements to review. It helps me to become more familiar with what they are taking on a daily basis, and it helps them to become more acquainted with what they’re putting in their body. We often can eliminate one or more supplements that they are taking, and we often put end dates on some more targeted supplements (i.e. correcting vitamin deficiencies), eliminating the tendency to continue a product for longer than is necessary.