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How to Safely Take Dietary Supplements

Article at-a-glance:

  • The US dietary supplement market is a $40 billion industry, with nearly 80% of Americans taking dietary supplements
  • This blog teaches you how to safely choose and consume the highest quality supplements
  • Know how to take the supplement for best results and to avoid potential problems with your medications
  • Understand how to ensure your supplement are safe (and that you’re taking them safely)
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The popularity of dietary supplements has increased every year in America since the 1970s. At the time there weren’t any federal standards for dietary supplements. That changed in 1994 when Congress passed the Dietary Supplement and Health Education Act (DSHEA). By then the US dietary supplement industry had grown to about 600 manufacturers marketing about 4,000 products. Just six years later, at the turn of this century, the Food and Drug Administration (FDA) estimated that the industry had grown more than 700%, companies were marketing more than 29,000 different dietary supplements and introducing to consumers an average of 1,000 new products every year. 1 At that time, consumers were spending $16.8 billion on dietary supplements.2

Today, the U.S. dietary supplements market size generates nearly $40 billion in annual sales. Not surprisingly with the COVID-19 pandemic, people focused on strengthening their immune system, which led to a surge in demand for immunity-boosting supplements.3 According to a survey by the Council for Responsible Nutrition (CRN), 77% of Americans consume dietary supplements, with vitamins and minerals the most popular, followed by herbals and botanicals.4

There’s no denying that supplements are mainstream. Overall, dietary supplements are safe, which is why the FDA regulates them as food products and not drugs. As the FDA notes on its website, “Some supplements can help assure that you get enough of the vital substances the body needs to function; others may help reduce the risk of disease.“ But, as the FDA notes, dietary supplements “should not replace complete meals which are necessary for a healthful diet.” 5 Dietary supplements are intended to be used just as the name implies—to supplement a healthy diet

While dietary supplements are considered extremely safe, it’s important to be an educated consumer to make sure you avoid any problems. The question, then, is not whether to take supplements—since most of us already do. The question is how to choose and consume the highest quality supplements safely, how to correctly read labels, what dosages are optimal, and to understandt which nutrients might be potentially toxic.

Here are some simple guidelines to help you safely choose and consume high-quality, effective dietary supplements.

Always read the label

By law, all dietary supplements must contain (1) a Supplement Facts Panel (SFP), (2) the Suggested Use, (3) the address of the company, and (4) any Caution or Warning statements. 

The SFP is the boxed area on the label that lists all the ingredients and their doses. Supplements often include:

  • Vitamins. These are essential nutrients that help regulate vital metabolic processes throughout your body. They’re often found combined in a multivitamin dietary supplement. They can be fat-soluble, such as vitamin A, vitamin D, vitamin E, and vitamin K; or water-soluble like B vitamins, or vitamin C.
  • Minerals. Minerals are critical to everything from bone health to fluid balance in the body. Essential minerals include calcium, magnesium, and iron; trace minerals are also needed but in much smaller amounts, for example, selenium or zinc.
  • Amino acids. Amino acids can exist on their own or be used as building blocks of protein. Examples of amino acids include L-theanine, lysine, tryptophan, tyrosine, leucine, isoleucine, taurine, valine, and others. This can also include protein and collagen powders.
  • Botanicals. These include whole plants, plant parts (eg, leaves, flowering parts, and roots), and plant extracts. Different plant parts are often used, such as hops flower or skullcap leaf and stem, for their calming and relaxing effects. Herbal extracts are often standardized to match what was used in scientific research. Those might include such common herbs as Huperzine A, an extract from Toothed Clubmoss (Huperzia serrata) that promotes healthy memory, and turmeric (from curcumin) to promote healthy inflammation balance
  • Other ingredients. This large category includes Coenzyme Q10 (CoQ10), which has been proven beneficial for the heart; nattokinase, which promotes healthy blood pressure and circulation, and proteolytic enzymes like bromelain that’s in Joint Relief.

Additionally, the SFP must also tell you the Serving Size, which is the number of capsules, tablets, or amount of powder you have to take to consume the dose of nutrients listed on the label. For example, Best Catch Omegas has a serving size of two capsules. If you take the full serving, you get the full amount of the omega-3 fatty acids EPA and DHA. If, instead, you take one capsule, then you’ll consume half the amount of each nutrient.

Dietary supplement labels may also contain Warning or Caution statements when they’re needed. For example, all iron dietary supplements must warn people to keep the product away from children. The FDA requires that the warning states, “Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep this product out of reach of children. In case of an accidental overdose, call a doctor or poison control center immediately.”6 That’s why NBI’s FerroSolve contains this statement as required by law. 

Dietary Supplement-Medication Interactions

Sometimes dietary supplements can interfere with the absorption or potency of medications. For instance, certain medications for heart disease or depression are less effective when taken with the botanical St. John’s Wort (SJW). In addition, some supplements such as nattokinase, ginkgo biloba, or fish oil can thin the blood and may need to be avoided if you’re also taking a prescription blood thinner.7,8

Nutrients in dietary supplements can affect the same biochemical pathways as medications. In some cases, that can make the effects even stronger. For example, since the nutrients in Sleep Relief promote sleep, the label cautions people against combining the product with sleep medications. The nutrient Huperzine A in Brain Blend works off the same biochemical pathway as the memory-enhancing medications Aricept or Tacrine. Based on their mechanism of action, these medications are called acetylcholine esterase inhibitors. Huperzine A is also an acetylcholine esterase inhibitor; therefore, the label cautions that people taking any of those medications should not take MitoForte.

Finally, as a general rule, it’s a good idea not to take dietary supplements at the same time as medications to avoid the risk that the nutrients could decrease the absorption of the medications. 

Eat Fat When Taking Fat-Soluble Vitamins

Fat-soluble vitamins are most commonly found in high-fat foods, such as fatty fish like salmon, egg yolks, avocados, and cooking oils. They include:

Vitamin A

Vitamin D

Vitamin E

Vitamin K

Additionally, some non-vitamin nutrients, such as beta-carotene, other carotenoids, and CoQ10, are fat-soluble. This means that all of these nutrients are absorbed better when there’s some fat present. 

To maximize their absorption, it’s important to take these nutrients with food containing some fat. For this reason, because Osteo-K and Osteo-K Minis contain Vitamin D and the MK4 form of vitamin K, their labels recommend people take the capsules with food. 

Avoid Overdosing

Dosages of nutrients in most supplements are well within the safe range and, in fact, have a wide margin of safety. Even so, it’s good to keep in mind that there’s a possibility of problems if you take too much of some nutrients. Some fat-soluble nutrients taken in high amounts can build up and present a risk of toxicity. For instance, pure vitamin A can accumulate in the liver and cause problems. Vitamin C at high doses can cause diarrhea, although there are good reasons sometimes to take vitamin C to bowel tolerance. Iron can cause constipation and nausea, while high doses of the trace mineral selenium can lead to brittle hair and nails, peripheral neuropathy, and gastrointestinal upset.9

Vitamin A

Pure vitamin A—and not vitamin A as beta carotene—can build up. It can do this in its vitamin form and can also do so in a related form of mediation called Accutane. This can lead to liver toxicity and birth defects in newborns.10

For this reason, most supplements, like Supreme Multivitamin, provide vitamin A in the form of beta-carotene. Beta carotene is composed of two molecules of vitamin A bound together. The body splits them apart to create vitamin A. Once the body senses that there’s enough vitamin A to do its job, the body doesn’t continue to make more vitamin A. That is why there’s no risk of toxicity from vitamin A delivered as beta carotene. 

Vitamins B3 and B6

Two water-soluble B vitamins can carry a risk for toxicity when taken in high doses. Vitamin B3 (niacin) is sometimes (though not often) given in high doses to manage high cholesterol. Niacin is mainly metabolized in the liver. Energy drinks can also contain large quantities of vitamins, including niacin. Excess niacin has been associated with liver injury, ranging from a mild elevation of liver enzymes to hepatitis and acute liver failure. The dosage associated with liver problems is usually around 3000 milligrams per day.11

Vitamin B6 (pyridoxine) in high doses can also be toxic. Vitamin B6 is used to treat multiple medical conditions and is available as a supplement over the counter. Vitamin B6 toxicity causes numbness and tingling in the extremities (hands, feet), a condition called peripheral neuropathy. This usually occurs only at doses above 1000 milligrams a day. When the vitamin is discontinued, symptoms generally improve.

Vitamin C

Vitamin C doesn’t cause toxicity, but it can create diarrhea. One of the places in the body where vitamin C is most concentrated is in white blood cells. These cells comprise our immune system that protects us from bacteria and viruses. When people get a cold or flu, their bodies’ ability to absorb vitamin C from the bowels increases. That is, they find that when they’re sick, they absorb up to ten times more vitamin C than when they’re healthy. This reflects the body’s ability to adapt to different situations that require different amounts of nutrients. To test this, people can do what’s called the Bowel Tolerance Test.

“To bowel tolerance” means that they take ever-increasing amounts of vitamin C, such as one thousand milligrams every hour for one day, then two thousand milligrams every hour for the next day, and so on, until their intestines can’t absorb any more. When this happens, they may experience some burning, loose stools, or watery diarrhea. This signals that they’ve reached bowel tolerance and need to decrease the amount taken to the dose at which these discomforts did not appear. Bowel tolerance can vary from person to person and can be as low as one thousand milligrams per day when healthy and greater than ten thousand milligrams per day when sick. 12


Similar to vitamin C, if your dose of minerals is too high you’ll get diarrhea. That’s because the minerals pull water into the bowels. If that happens, simply reduce the amount of minerals you’re taking to a dose that doesn’t cause this issue.

Verify Purity and Rely on Trusted Manufacturers 

When choosing dietary supplements, rely on trusted names and sources. As with all industries, there are some bad actors out there who cut corners and create unsafe or inferior products to pump up their profits. They care more about making money than helping consumers safely improve their health. This can include skimping on important testing to make sure their products don’t contain toxic metals. The FDA does not require this testing, so it’s up to you to confirm that it’s been done. I discuss this at length in my blog, Why Toxic Metals May Be Your Issue.

One example is chronic arsenic toxicity from a chitosan supplement. Chitosan is made from the hard outer skeleton of shellfish, including crab, lobster, and shrimp. It is thought to adsorb toxins and improve health.13 Another example are the heavy metals found in some traditional Chinese medicines, and the lead found in some Ayurvedic herbal medicines.14,15

You may be wondering how you can determine which manufacturer is safe. Generally, large supplement companies that conduct research on products and have been trusted names for years are reliable, like NBI that has been in business since 2006. In addition, you can check manufacturer websites for a section on their manufacturing quality. Not all companies show you this information, but the ones who invest resources into ensuring their products meet or exceed the highest industry standards, and whose manufacturing facility is accredited by third-party organizations, typically want consumers to know that. The NBI website has an Our Quality page describing how we approach the research, development, and manufacturing of our products. 

Consumers can also reach out to companies and ask for a copy of the Certificate of Analysis (COA) for specific products. A COA is a document that shows the finished product has undergone testing prior to being released to the market. Each time a product is manufactured, another COA should be created for that specific batch. The COA shows whether the nutrients and their doses that are in the product match what’s on the label and whether the finished product is free of toxins like bacteria, fungal spores, and toxic metals. If a company refuses to provide a COA to you, then you may want to think twice about purchasing their products. 

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1Institute of Medicine and National Research Council. Dietary Supplements: A Framework for Evaluating Safety. Washington, DC: The National Academies Press. 2005. Pp. 19 [Report]

2Gibson JE, Taylor DA. Can claims, misleading information, and manufacturing issues regarding dietary supplements be improved in the United States? J Pharmacol Exp Ther. 2005;314(3):939-944. [Article]

3Dietary Supplements Market Size, Share & Trends Analysis Report By Ingredient (Vitamins, Proteins & Amino Acids), By Form, By Application, By End User, By Distribution Channel, And Segment Forecasts, 2021 – 2028. Grand View Research. Feb 2021. [Report]

4Vogtman H. Dietary Supplement Use Reaches All Time High. CRN. Sept 2019. [Report]

5U.S. Food & Drug Administration. What You Need to Know about Dietary Supplements. Nov 2017. [Report]

6Shital K. Iron Poisoning. WebMD. Oct 2020. [Report]

7US Food & Drug Administration. Mixing Medications and Dietary Supplements Can Endanger Your Health. 2014. [Report]

8Asher GN, Corbett AH, Hawke RL. Common Herbal Dietary Supplement-Drug Interactions. Am Fam Physician. 2017 Jul 15;96(2):101-107. [Article]

9Wooltorton E. Too much of a good thing? Toxic effects of vitamin and mineral supplements [published correction appears in CMAJ. 2003 Aug 19;169(4):283]. CMAJ. 2003;169(1):47-48. [Article]

10Ross SA, McCaffery PJ, Drager UC. Retinoids in Embryonal Development. Physiological Reviews. Vol 80 (3). July 2000, pp. 1021-1054 [Article]

11Habibe MN, Kellar JZ. Niacin Toxicity. [Updated 2020 Jun 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. [Article]

12 Hemminger A, Wills BK. Vitamin B6 Toxicity. [Updated 2020 Nov 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. [Article]

13Caraccio TR, McGuigan M, Mofenson HC. Chronic arsenic (As) toxicity from Chitosan[R] Supplement. 2002;40(5):644(641) Clin Lab Med. 2006 Mar;26(1):67-97, viii. [Article]

14Ernst E, Thompson Coon J. Heavy metals in traditional Chinese medicines: a systematic review. Clin Pharmacol Ther. 2001;70(6):552-560. [Article]

15Gunturu KS, Nagarajan P, McPhedran P. Ayurvedic herbal medicine and lead poisoning. J Hematol Oncol. 2011 Dec 20;4:51. [Article]

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