There is no question that dietary supplements can provide important nutrients and strongly support wellness when used properly. Many people assume that supplements are completely safe because they are “natural.” It is important to understand that dietary supplements can also cause harm. Here are my five top scenarios in which dietary supplements can cause harm.

Excessive nutrient dosing from multiple supplement products

Taking too much of a particular nutrient can be harmful. Most people know this, but the problem lies in the “real-world” way that supplements are often used. I commonly see patients taking one supplement for sleep, one for vision, one for this issue or that issue… Before long they end up with a lot of different bottles. The problem here is not that they take different supplements. The problem is that they never read each product label to check the total amounts of each individual nutrient they are ingesting. The result is duplication of certain nutrients which can lead to excessive dosing. The most recognized nutrients that are dangerous in overdose are the fat-soluble vitamins (A, D, E, K), but there are many others that you simply do not want to be taking in excess such as certain B vitamins, metals (iron/copper) and other vitamins.

The solution? Be sure you read ALL product labels for each supplement you take and be sure that you are not duplicating nutrients in excess. Be warned, the print on the labels can be very small and you may need a magnifying glass to do this. Also, don’t forget to include the ingredients of any green powders, protein powders or tinctures you may also be taking.

Overdoing it with nutrients on purpose

This is much less common, but I see it at least a few times every year. Example: someone takes vitamin A (or a vitamin A containing supplement) for their eyesight or for immunity/antiviral purposes. At some point they think that if a small amount is good, then more should be even better. They then increase the dose and continue it for years. I use the Vitamin A example because long term use of high dose Vitamin A is very dangerous. Harm can and does occur. I’ve personally seen 2 cases of severe liver damage (cirrhosis) caused by chronic vitamin A overdosing while working as a hospital doctor years ago.

The solution? When it comes to supplements, more is not necessarily better. Be sure you read the product labels and stay within the recommended daily allowance unless your health practitioner tells you otherwise.

Supplement Additives

You wouldn’t believe the things that get added into some vitamin and supplement products. I took the ingredient list for one of the top selling multivitamins in the USA and removed all the nutrients. You can see that this supposedly “health promoting” product is actually full chemicals and other additives that are not healthy. Clearly, if you don’t read the label, you would never know that it contains:Plastic jar with supplement facts of multivitamins in woman hands. Close-up of Supplement facts of Dietary Supplement Bottle.

  • GMOs (Genetically Modified Organisms): Modified Corn Starch, Corn Starch, Pregelatinized Corn Starch.
  • Preservatives: BHT (to preserve freshness).
  • Food colorings: Blue 2 Lake, Red 40 Lake, Titanium dioxide, Yellow 6 Lake.
  • Excipients: Crospovidone, Talc, Hypromellose.
  • Trans fats: Hydrogenated Palm Oil.

The solution? Read the supplement facts before you buy anything and only buy supplements from companies that put quality and purity first. An Integrative or Functional practitioner can help you with this. Additionally, the online dispensary Fullscript is a trusted source of high-quality supplements that I use and depend on.


The FDA has issued warnings of hidden drug ingredients in certain supplements. [i] Commonly found contaminants in dietary supplements include heavy metals, microbial contaminants, [ii] pesticides/herbicides, pharmaceuticals and solvents. Fish oils/omega 3 fatty acids are especially affected by contamination, as they are derived from fish that swim in polluted oceans. Common issues with fish oil supplements include excessive levels of PCBs, dioxins and mercury.

The solution? Choose supplements that are high quality, manufactured with Current Good Manufacturing Practices (cGMPs) and from a company that uses third party testing of its products to rule out contamination.

Drug-Supplement Interactions

This is a huge topic that I can’t cover in one paragraph. Suffice it to say that If you take any prescription medications, always discuss supplement use with the prescribing practitioner before adding any supplements into the mix.

Take Home Messages

If you use dietary supplements, it is extremely important that you get in the habit of reading the supplement facts for each bottle. You must know what you are taking to avoid the potential risks mentioned in this article including but not limited to nutrient overdose and ingestion of exogenous bad stuff (think food colorings and chemicals). An Integrative or Functional Medicine practitioner can teach you how to recognize high quality companies and products. Additionally, the dispensary Fullscript is a trusted source of high quality, carefully vetted supplements that you can access here. If you have additional questions or need further guidance, please consider scheduling an appointment with me. You can be sure that I will ask you to bring ALL of your supplement bottles so I can review them in the office😉.

Sharon Goldberg  is a Santa Fe based Integrative and Functional Medicine Physician who specializes in personalized preventive and wellness focused patient care. She is Board Certified in Internal Medicine since 2000 and has advanced training in Tropical Medicine and Hygiene. She has over two decades of practice experience working with both complex chronic illness and disease prevention. She is a medical educator, peer reviewer and coauthor of integrative and prevention related clinical research.

To schedule an appointment with Dr. Goldberg click here.


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The information provided on this site is for informational purposes only. Dr. Sharon Goldberg and Glow Health, PA assume no responsibility and make no claims in treatment or cure of any disease or illness. The information provided by is not intended to substitute for medical advice from your physician or healthcare professional and is intended to support, not replace, the relationship that exists between a patient/site visitor and his/her physician. If you have/suspect you might have a health problem, you should consult your medical doctor.  Supplements can interact with prescription medications. Be sure to consult with a healthcare professional before starting any diet, exercise, or supplement.