Part 2 of this article on dietary supplements features an interview with Erin D. Michos, MD, MHS, FACC, FAHA, associate professor of medicine and epidemiology and associate director of preventive cardiology at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins School of Medicine in Baltimore, Maryland.

Continue Reading

To read part 1 of this article, please click here.

Medical Bag: What are your thoughts on why many healthcare providers are not familiar with the way dietary supplements are regulated?

Erin Michos, MD: In 2015, Americans spent $21 billion dollars on vitamins and herbal supplements, and approximately half of US adults take a supplement of some kind.1 The question is why — why do people continue to take these when study after study has shown no benefit? Is this really a good use of money spent?

I am not sure that healthcare providers realize that dietary supplements can refer to a whole host of various products taken by mouth that contain a “dietary ingredient” intended to supplement diet. Many patients often don’t even report to their physician that they are taking these products because patients often think of them as “natural” and not a biologically active product. This can be dangerous because drug-drug interactions can occur between many supplements and prescription medications.

Notably, dietary supplements are not intended to treat, diagnose, cure, or alleviate the effects of diseases. However, many patients specifically to improve their health and are often misled by false advertising to believe they are improving their health, when supplement are not needed by the vast majority of US adults. Most people can get all required vitamins and nutrients through a heart-healthy diet.

Another major issue that healthcare providers may not be aware of is that, as far as regulations go, dietary supplements fall under the umbrella of “food,” not drugs. 

The Dietary Supplement Health and Education Act (DSHEA) governs dietary supplements under a different set of regulations than those covering food and drug products. Federal law does not require dietary supplements to be proven safe to the Food and Drug Administration (FDA)’s satisfaction before they are marketed, as it does for prescription and non-prescription drugs. The law also does not require the manufacturer or seller to prove to the FDA’s satisfaction that the claim is accurate or truthful before it appears on the product. The FDA’s first opportunity to take action against a product that presents a significant or unreasonable risk or is adulterated or misbranded, is after the product enters the market.

Once a dietary supplement is on the market, the FDA has certain safety monitoring responsibilities, including monitoring the mandatory reporting of serious adverse advents (AEs) by dietary supplement companies and voluntary AE reporting by consumers and healthcare professionals.

Again, I am not sure that patients — or even many healthcare providers — realize that manufacturers of dietary supplements do not need FDA approval before producing or selling dietary supplements.

Medical Bag: What are some of the issues that may arise due to this lack of awareness and misconceptions regarding the regulation of dietary supplements?

Dr Michos: As I mentioned, federal law does not require dietary supplements to be proven safe to the FDA’s satisfaction before they are marketed. It is not legal to market a supplement as a treatment or cure for a specific disease, or to alleviate the symptoms of a disease.

Many patients and healthcare providers may think that these dietary supplements are benign, so what’s the big deal? But it is estimated that 23,000 emergency department visits every year are due to AEs from supplements.2 [Editor’s note:The authors of the 2017 commentary suggest that this number is likely closer to 10,000 because further examination of the data revealed that one-third of these visits could actually be attributed to “pill swallowing issues and not the contents, and 20% of the visits were due to unsupervised ingestion by children and in only a few cases would require intervention.”.3 They added, “Furthermore, a number of substances included in the analysis as dietary supplements should have been excluded, because they were legally drugs or other chemicals and not dietary supplements by definition.”]

Certain antioxidants and vitamin B3 (niacin) have been associated with an increased risk for mortality.4 With multivitamins, it is unlikely that when taken in moderation they can cause much harm — but again, we have observed no benefit, so why take them at all?5

Furthermore, there has been some potential harm reported for antioxidant vitamins beta-carotene and vitamin E, with increased risk for lung cancer in smokers. As a result, the US Preventive Services Task Force (USPSTF) has advised against taking beta-carotene and vitamin E supplements.6

In my prior research, I raised concerns about the use of calcium supplements, as they may increase the risk for vascular calcification in the coronary arteries,7 and increase the risk for kidney stones8 or colon polyps.9 It’s not really clear whether calcium supplements even reduce the risk for fractures in community-dwelling adults — the USPSTF deemed the data insufficient to recommend calcium supplements for the purposes of fracture prevention. So, I think patients and their healthcare providers may think they are getting more of a benefit than they really are.

Medical Bag: What do you recommend that providers do in order to increase their knowledge in this area?

Dr Michos: One concern is that patients may not think to report to their doctor that they take these supplements, so providers need to know to ask about them and to document supplement use in the patient’s electronic medical record along with their other prescription medications. This is critical because many supplements can cause dangerous AEs when combined with prescription medications.

For example, both fish oil and Ginkgo biloba can potentially cause an increased risk for bleeding when combined with blood thinners, and St John’s wort can interact with antidepressants. There are many similar examples.   

Physicians need to educate themselves about potential interactions with supplements when prescribing drugs so they can best educate their patients about the potential for harm. In most cases, the supplements are not indicated and can be stopped. A pharmacist or online drug interaction checker can be helpful when there are questions about interactions.

I don’t think many healthcare providers even realize that some supplements can interfere with medical tests. For example, biotin (B7) is a water-soluble B vitamin found in multivitamins, prenatal vitamins, and dietary supplements marketed for hair, skin, and nail growth, according to the FDA. The recommended daily allowance of biotin is 0.03 mg, a level that typically does not interfere with laboratory test results. But the supplements marketed for hair, skin, and nails can contain up to 20 mg of biotin, which is more than 650 times the recommended allowance. Immunoassays rely on biotin-streptavidin binding to capture antibodies, and biotin is used in immunoassay tests for cardiac troponins, thyroid-stimulating hormone (TSH), and others, and these assays can be affected by biotin.

Medical Bag: What are some of the remaining needs in this area, in terms of research or otherwise?

Dr Michos: For the vast majority of supplements, there does not appear to be any benefit, and more is not better if the patient doesn’t have a nutritional deficiency. However, there are some situations in which they may be helpful, such as vitamin B12 supplementation, which is necessary for vegans. Another example is a study that found that folic acid supplements may reduce the risk for stroke in China,10 where foods are not supplemented with folate. However, this supplementation does not appear to be beneficial in countries in which there is adequate folate intake from fortified food products.3 In the VITAL trial (Vitamin D and Omega-3 Trial; NCT01169259), there did not appear to be any benefit overall for fish oil intake for overall cardiovascular or cancer benefit, but there did appear to be possible benefit for heart attack risk and a benefit for cardiovascular disease risk reduction in a subgroup of individuals with fish low intake.11

We need more research to understand which types of patients might benefit from supplements. We also need more data about the harms of supplement use, which is harder to capture since they are not regulated and tracked in the same way as prescription drugs.


  1. Gahche JJ, Bailey RL, Potischman N, Dwyer JT. Dietary supplement use was very high among older adults in the United States in 2011-2014. J Nutr. 2017;147(10):1968-1976.
  2. Geller AI, Shehab N, Weidle NJ, et al. Emergency department visits for adverse events related to dietary supplements. N Engl J Med. 2015;373(16):1531-1540.
  3. Stohs SJ, Preuss HG. What health care professionals should know about the regulation and safety of dietary supplements. J Am Coll Nutr. 2017;36(4):306-309.
  4. Jenkins DJA, Spence JD, Giovannucci EL, et al. Supplemental vitamins and minerals for CVD prevention and treatment. J Am Coll Cardiol. 2018;71(22):2570-2584.
  5. Kim J, Choi J, Kwon SY, et al. Association of multivitamin and mineral supplementation and risk of cardiovascular disease. Circ Cardiovasc Qual Outcomes. 2018;11(7):e004224.
  6. Moyer VA; for the US Preventive Services Task Force. Vitamin, mineral, and multivitamin supplements for the primary prevention of cardiovascular disease and cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014;160(8):558-564.
  7. Anderson JJ, Kruszka B, Delaney JA, et al. Calcium intake from diet and supplements and the risk of coronary artery calcification and its progression among older adults: 10-year follow-up of the Multi-Ethnic Study of Atherosclerosis (MESA). J Am Heart Assoc. 2016;5(10).
  8. Weaver CM, Alexander DD, Boushey CJ, et al. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation. Osteoporos Int. 2016;27:367-376.
  9. Crockett SD, Barry El, Mott LA, et al. Calcium and vitamin D supplementation and increased risk of serrated polyps: results from a randomized clinical trial. Gut. 2019;68:475-486.
  10. 10.  Huo Y, Li J, Qin X, et al. Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China. JAMA. 2015;313(13):1325-1335.
  11. 11.  Manson JE, Cook NR, Lee IM, et al; for the VITAL research group. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer. N Engl J Med. 2019;380(1):23-32.