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Do you really need to take a vitamin? 5 things to know before you buy

In the largely unregulated supplement industry, products may be ineffective or even dangerous.

Amanda Capritto
9 min read

Supplements: To take them or not? 

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It seems like every corner of the internet is overstuffed with ads for vitamins, herbal remedies, fat-loss supplements, muscle-building shakes and sleeping pills. 

As someone who's worked in the health fitness industry for years, I know that much, if not most, of it is just clutter. It's charlatans and hustlers trying to make a quick buck off of your pain points. It's great marketers who know that phrases like "lightning fast weight loss" and "banish cellulite forever" sell products that may or may not be straight-up flimflam. 

In the largely unregulated supplement industry, many products are ineffective, full of fillers or undisclosed ingredients. Some are downright dangerous. Who can you trust? How do you know which supplements are best for you? What products are actually effective -- and safe to take? 

I want to preface the rest of this article with two very important disclaimers:

First, it's impossible to cover everything you need to know about choosing safe and effective supplements in one article. If you want to learn more, you should read official information from the Food and Drug Administration (FDA), the Office of Dietary Supplements (ODS) and the US National Library of Medicine. While I cite many primary studies in this article, you can browse the PubMed database for more information on specific supplements, their uses, benefits and risks. 

Second, although I have training in nutrition, anatomy and physiology, I am not a registered dietitian nor a doctor of any sort. If you are interested in taking supplements for a particular symptom or medical condition, please, please, please consult a registered dietitian or your doctor before doing so. 

Now onto what you should know about supplements before you waste your money. 

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1. Supplements aren't strictly regulated by the FDA or the USDA 

Currently, the supplement industry is largely unregulated, especially compared to the food and drug industries. The FDA still uses an act passed nearly 20 years ago -- the Dietary Supplement Health and Education Act of 1994 (DSHEA) -- that only has one real stipulation: "Manufacturers and distributors of dietary supplements and dietary ingredients are prohibited from marketing products that are adulterated or misbranded."

This means the manufacturers themselves are responsible for testing the safety and efficacy of their products, as well as for labeling their own products. The FDA can crack down on a supplement after it hits the market if it's incorrectly labeled or unsafe, but by that time, damage may already be done. 

You can learn more about what's required of supplement manufacturers by reading the FDA's FAQ on dietary supplements. However, FDA Commissioner Scott Gottlieb did announce in a February 2019 statement that he plans to implement stricter regulations, so things are definitely looking up for the supplement industry. 

Nonetheless, here are a few examples of what has happened in the past because of the low-level regulation:

  • Companies have sold highly concentrated caffeine powder and liquid in bulk to consumers. The FDA has since ruled that an illegal and unsafe practice.
  • A supplement brand sold products with dangerous hidden ingredients. The FDA has announced warnings to both consumers and the company.
  • Supplement companies illegally claimed to treat opioid use disorder. The FDA posted warning letters to the companies.
  • Nearly 20 supplement brands sold products with unlawful claims about treating Alzheimer's disease. The FDA sent warning letters to all of the companies.

2. You shouldn't take the same supplements as everyone else


Personalized vitamins are better than taking whatever you find on the shelf, but you should still consult a doctor or dietitian about supplements for particular concerns. 


If your diet, lifestyle, fitness routine, sleep habits and health status aren't the same as anyone else's, why would it make sense to take the same supplements as everyone else? 

For some supplements, this is obvious: You probably wouldn't feel inclined to take a calorie-dense, high-protein and high-carb post-workout shake if you weren't trying to build muscle. You also probably wouldn't reach for sleep aids if you don't have trouble sleeping at night. 

For other supplements, the disconnect isn't so conspicuous. Everyone needs vitamins, right? 

Yes, everyone does need vitamins and minerals and other certain nutrients (here's a very helpful PDF chart from the FDA on the main nutrients, their functions and RDAs), but not everyone needs the same amount of the same nutrient. 

Take vitamin B12 as an example: People who eat a vegan or vegetarian diet may benefit from supplementing with B12 because this vitamin is found primarily in animal products or fortified products. If you eat eggs, dairy products, chicken, seafood or steak, you likely don't need additional vitamin B12. 

If you're interested in learning more about which vitamins you actually need, I highly recommend reading The Vitamin Solution by Dr. Romy Block and Dr. Arielle Levitan, two doctors who founded Vous Vitamin, a personalized multivitamin company. 

I found this book to  lay out all of the essential knowledge on vitamins, minerals and other supplements in a way that's easy to understand and can help you determine which supplements are best suited to you -- or at least open up a helpful discussion with your doctor.

3. Supplements don't replace whole foods


Supplements will never be as good as eating whole, nutrient-dense foods like fruits and vegetables.

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It's unfortunately a myth that taking vitamins and supplements can replicate a healthy diet. Just like you can't "out-exercise" a poor diet, you can't "out-supplement" one either. Vitamins can certainly help bridge the gap between what you get from your diet and what you don't, but using supplements as a way to "fix" your diet won't work. 

There are so many nuances at play here. For example:

That list is far from comprehensive, but you can see that vitamins and supplements don't just magically undo poor eating habits. Scientific conclusions vary greatly -- from "we don't need vitamins at all" to "the benefits outweigh the risks" -- but the general consensus seems to be that vitamins and supplements can help prevent nutrient deficiencies in certain populations and when taken correctly and support health in conjunction with a nutritious diet.

4. Yes, you can overdose vitamins and supplements


Taking too many vitamins can result in dangerous side effects, so be careful to check the Recommended Daily Allowance (RDA) for each vitamin you take. 


One common vitamin myth is this: "If I take too many vitamins, it's fine, because my body will only keep what it needs and get rid of the rest as waste." 

This is a pervasive mindset but a dangerous one. You can, in fact, overdose on vitamins. The term is "vitamin toxicity" and it can happen with any vitamin. For almost every vitamin, there is an established Recommended Daily Allowance (RDA) or Adequate Intake (AI), as well as a Tolerable Upper Intake Level (UL). 

The RDA or AI signifies an ideal daily intake while the UL indicates the high end of what's safe to consume. RDAs, AIs and ULs are all values under Dietary Reference Intakes (DRIs), the set of reference values assigned to foods and supplements for consumption.

Recently, experts have seen an increase in vitamin D toxicity, likely related to the touting of vitamin D's benefits on immune function, bone health and mood. 

It's not just vitamins that can be toxic either: Minerals taken in high doses can be toxic, as can electrolytes, herbs and sports supplements. Zinc, for example, a mineral known and loved for its immune-boosting properties, can actually cause immunosuppression in extremely high doses.

Pre-workout supplements high in caffeine can cause abnormal heart rhythms and severe overdoses can be fatal. Potassium, a well-known electrolyte found in foods such as bananas and spinach and in sports drinks, can also cause toxicity. Called hyperkalemia, this condition can lead to muscle weakness, fatigue, nausea and, in severe cases, life-threatening heart arrhythmias. 

Surpassing the UL of any vitamin, mineral, electrolyte or other supplement can cause harm, so be careful to do your research on any supplements you intend to take. 

5. Supplements may dangerously interact with medications you take


Some supplements can reduce the effectiveness of certain medications or result in side effects -- talk to your doctor about supplements if you take medications. 

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If you currently take prescription or over-the-counter medications regularly, you should talk with your doctor about drug-nutrient interactions

A drug-nutrient interaction is any reaction that occurs between a vitamin, mineral, antioxidant, electrolyte or other nutrient and a medication. A drug-supplement interaction is any reaction that occurs between a supplement and a medication. 

Good intentions to supplement your diet with vitamins, minerals and herbs can backfire and cause complications. Take these examples:

How to choose the right supplements for you

Protein powder

Supplementing smartly can optimize your health and fitness, but supplementing poorly can potentially be dangerous.

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If you're generally healthy and want to take supplements for overall health, I think the best bet is to use a personalized multivitamin service, such as Vous Vitamin, Baze or Persona Nutrition. This isn't as good as going to a doctor or dietitian, but it's still better than just swiping the first multivitamin bottle you see into your cart at the grocery store. 

Some of these companies have more thorough personalization processes than others, but in general, with a personalized multivitamin, you can feel confident that you're not getting too much of a specific vitamin or consuming a vitamin that may be necessary or actually harmful to you. 

If you don't go that route (and even if you do), you should always (always!) look for signs that a supplement is legitimate. By legitimate, I mean it's undergone third-party testing and/or evaluation, and it is certified not to include any ingredients other than what's on the label (aka it doesn't have any shady fillers). Those signs are: 

  • National Sanitation Foundation (NSF) certification. The NSF is a third-party evaluation agency for food and dietary supplements. When a supplement sports the NSF-certified label, it means it has undergone a scrutinous safety and risk assessment, and continuously undergoes "regular on-site inspections of manufacturing facilities and regular re-testing of products to ensure that they continue to meet the same high standards required to maintain certification over time." 
  • US Pharmacopeia (USP) Verified Mark. The USP is a nonprofit, independent organization that vets medications, foods and dietary supplements to determine their safety and efficacy. The USP Verified Mark on a supplement means that supplement meets four critical components, which you can read about on the USP standards for supplements page.
  • Good Manufacturing Practices (GMP) certification. This is the one FDA-related certification for supplements. The FDA has established Good Manufacturing Practices for supplement production, and dietary supplements that have this certification meet the FDA's guidelines for production.

Even better yet, look for a nutrition facts label versus a supplement facts label. A nutrition facts label means the product is sold as a food product, not a supplement, which means it has been evaluated and approved by the FDA for human consumption. A whole-food supplement with a nutrition facts label, an NSF certification, a USP Verified Mark and GMP certification is the best of the best.

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To avoid vitamin toxicity, check the labels of every supplement you take. If you take multiple supplements every day and also get vitamins from food, you can put yourself at risk for vitamin toxicity -- for instance, if your protein shake is fortified with vitamin B12 and your multivitamin contains 250% of the DRI for vitamin B12, you may want to alternate them or choose a different protein shake that isn't fortified. 

Finally, I'll end with the same sentiments I opened with: Please consult your doctor or a registered dietitian if you're interested in taking vitamins or supplements for a specific symptom or medical condition. 

Not only can supplements dangerously interact with medications you may be taking already, it's important to rule out any medical conditions that may need to be treated with prescription medication. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.