Are Your Supplements Safe? Here's How to Tell

Learn how to know if a supplement is of good quality—discover third-party testing and supplement safety checkers so you can make informed choices for your well-being.

Ashley Reaver
By Ashley Reaver
Lucia Gcingca
Edited by Lucia Gcingca

Published March 6, 2024.

A woman holding a bottle of pills in her hand.

In 2021, the global dietary supplements market soared to a staggering estimated value of nearly USD 152 billion. With so many supplements constantly flooding the market, how can you tell which ones are the best for you? Which ones are safe? Which supplement brand should you choose? And, more importantly, which supplements live up to their hype?

The start of a new year is accompanied by plenty of resolutions to adopt a healthier lifestyle, and supplement providers follow suit with their offerings. So, we came up with some helpful strategies to help you sift through the marketing gimmicks and choose the supplements that are the safest and the most effective for you.

Dietary supplement usage in the United States

Over 50% of adults in the United States report using at least one dietary supplement.[1] However, just because supplements are highly consumed doesn’t mean they are highly regulated. 

Are vitamins and other supplements approved by the FDA?

Unlike pharmaceutical drugs, the Food and Drug Administration (FDA) doesn't regulate dietary supplements. That means that supplements are not subject to the same strict processes as clinical trials to prove their effectiveness, purity, or marketing claims before entering the market.

They are, however, regulated under the Dietary Supplement Health and Education Act (DSHEA), which protects consumers' right to access supplements for wellness. [2] 

 Important note on the act

The DSHEA does not check supplemental health claims or guarantee they're safe and effective.

» Discover everything you should know about taking supplements

Determining which supplements you should be consuming

Make sure you need the supplement

How do you know you need a supplement? Your friend, mother-in-law, online ad, or flashy headlines aren’t good sources for recommendations. The best way to find out if you need a supplement is to take the proper assessment, like a blood test, to make sure you actually need it.

» Working on your fitness? Look out for these supplements

Prioritizing nutrient-rich foods to fulfill your dietary needs

Always see if you can get the vitamin, mineral, herb, or substance in the form of food first. Only when it isn't possible to make diet or lifestyle changes should you consider adding that specific supplement. 

Check for supporting and approved science

If a supplement sounds too good to be true, it probably is. Credible supplements have peer-reviewed scientific literature that supports their use and effectiveness.

Also, ensure that the recommended dosage is supported by approved science. If it is, it will be discussed in the supporting studies as well. More doses do not always equal better results, so beware of mega doses.

All the supplements that InsideTracker recommends are supported by numerous studies and come with personalized dosage instructions.

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Special considerations for safe supplement use

Many supplements can interfere with prescription drugs. Ensure that the supplement can be safely incorporated with your current medications. Women who are pregnant or breastfeeding should also consult their doctor before beginning any new supplements. [3, 4]

» Check out expert tips for taking your supplements from registered dietitians

5 strategies for selecting safe supplements

Once you've decided a supplement is a good idea, here are a few ways to make sure you are getting the best one:

1. Buy supplements from a reputable source

Since supplements aren’t regulated, many companies do not go through the hassle of quality control to ensure the nutritional label matches the product and that the ingredients in the bottle are pure. Large national, trusted supplement brands are better at this than small, one-off companies because they can afford proper quality control measures.

2. Look for a third-party verification on the supplement bottle 

Many supplements are certified by USP (the U.S. Pharmacopeial Convention) or NSF International, third-party organizations that conduct testing on supplements to determine if what is on the label is actually in the bottle and that the product does not contain high levels of contaminants, such as heavy metals.

How do you tell if a supplement is third-party tested? You just look out for these credentials on a supplement label. It is expensive, however, and not all companies can afford the analysis. [5, 6]

3. Look for third-party verification online

If you're struggling to find out if a supplement is third-party tested, try some third-party websites, like and They provide an analysis of supplements. These websites also publish lists of the highest-quality supplements. [7, 8]

4. Buy organic herbal supplements

Many herbal supplements will not have third-party verification. To ensure their level of contamination is lowest, buy organic herbal supplements to ensure that harmful pesticides are not included in the supplement.

Many credible companies provide information on where their herbs are sourced and are proud to share. Purchasing from large, well-known brands also increases the likelihood that the supplement contains the appropriate amount of the active ingredient, such as iron, vitamin C, or magnesium.

» Find out how to take iron supplements to maximize absorption

5. Choose single-ingredient supplements

Supplements that contain a single ingredient are more likely to contain the amount of the ingredient advertised on the label and less likely to have high levels of contamination. Many companies selling “proprietary blends” or multivitamins do not have to report any ingredient amounts on their labels and, thus, should be avoided.

a pile of pills sitting on top of a wooden table

Extra recommendations for supplement safety

  • Only take a supplement for the recommended length of time: If you are taking a supplement, make sure you are taking it only for the recommended duration. If you are taking supplements in response to a biomarker level, recheck your biomarker to ensure continued supplementation is needed.
  • Store supplements in the appropriate environment: Some supplements need to be refrigerated, and others need to be kept away from light. Be sure to follow storage instructions.
  • Begin one new supplement at a time: Like any good experiment, change only one thing at a time. When starting a new supplement, keep your normal routine so you can identify if a supplement is the cause of adverse effects.

Stop taking the supplement if you experience adverse effects!

If you are feeling ill or “off” after beginning a new supplement, stop taking it. The adverse effects of supplements should also be reported to the FDA

» Uncover the truth behind anti-aging supplements, vitamins, and pills

How to tell if vitamins are good quality

InsideTracker’s supplement recommendations are supported by peer-reviewed scientific literature. We provide dosages, frequency, duration, and warning information. Most importantly, we only recommend supplements if they are right for your biochemistry.

While we do not support any specific companies, we hope this information will help you choose the best brands for the supplements we recommend. After all, your health is our top priority!


[1] Kantor, E. D. et al. Trends in Dietary Supplement Use Among US Adults From 1999-2012. JAMA 316, 1464 (2016).  [2] Morrow, J. D. et al. American Society for Clinical Pharmacology and Therapeutics Position Statement on Dietary Supplement Safety and Regulation*. Clin. Pharmacol. Ther. 77, 113–122 (2005). [3] Choosing and using dietary supplements safely. Available at: choosing-safely. (Accessed: 13th January 2017) [4] Nutrition, C. for F. S. and A. Information for Consumers - Tips for Dietary Supplement Users. [5] USP Dietary Supplement Standards and USP Verified. Available at: (Accessed: 13th January 2017) [6] What Is NSF Certification? - NSF International. Available at: (Accessed: 13th January 2017) [7] - independent tests and reviews of vitamin, mineral, and herbal supplements. Available at: (Accessed: 13th January 2017) [8] Supplement Ratings and Reviews - Labdoor. Available at: (Accessed: 13th January 2017)