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What to Watch Out for When Choosing a Supplement -- Supplement Bottle Label Close-up


It's very easy to buy the wrong product when shopping for a vitamin or supplement.

At, we've purchased, tested, and carefully reviewed the labels of more than 6,000 dietary supplements and found problems with more than 20% of them. We've seen just about every type of problem that can occur with vitamin, mineral, herbal, oil, and other types of supplements, as well as with nutrition powders, drinks, bars and various health foods.

Based on our experience, below are the top six red flags that our experts think you should watch out for when buying vitamins and other supplements.

Of course, products with none of these red flags can still have been improperly made, mislabeled, contaminated, spoiled, or provide pills that won't properly break apart. You won't know this without laboratory testing like the type we do in for our product reviews, which you should also consider using to help you avoid problems and choose the right supplement.

1. Labels that don't tell you how much you're getting

There are several situations where this can happen:

  • "Proprietary blends," "proprietary formulas," and "complexes" may be named to sound like one of the primary ingredients you want, but may contain little of that ingredient.

    Proprietary blends and formulas, as well as complexes, are often developed around an expensive ingredient because this allows a company to use less of that ingredient, creating a formula in which the expensive ingredient is just a small part of the formula. We have seen this with ingredients such as CoQ10, curcumin, SAMe, and chondroitin in joint supplements.

    We also see proprietary formulas marketed for uses such as cognition, nerve pain, or weight management where a company may try to impress the consumer with a laundry list of ingredients having only shreds of evidence relating to the intended use. In most cases, the formulas themselves have not been clinically tested.

    Be sure to look for products that show the amount of each ingredient. This will also help you determine which ingredients seem to help you and which don't.

  • Minerals are unstable by themselves and need to be stabilized in supplements as "salts," meaning they are chemically bound to another compound. This is not a problem, but the majority of the weight of these salts can often be the other compound and not the mineral. For example, only 14% of magnesium bisglycinate is magnesium and only 11% of magnesium citrate is magnesium. This doesn't mean these aren't good forms of magnesium, but it is important that a label tell you exactly how much of the mineral you are getting. For example, a good label may read "Magnesium (as magnesium citrate) 110 mg," so you know that you're getting 110 mg. A misleading label for the same product may read "Magnesium citrate 1,000 mg," leading you to believe that you're getting a lot more magnesium than the 110 mg it provides (since the remaining 890 mg is citrate and not magnesium). A similar problem exists when trying to get choline from supplements.

  • When people buy fish oil, they really want the omega-3 fatty acids, not the rest of the oil, but the concentration of omega-3s can range from about 25% to 90% of the fish oil. Prescription fish oils, for example, are closer to 90% omega-3s. A supplement that claims "1200 mg" of fish oil, may provide just 300 mg of omega-3s. If you're trying to get a high dose of omega-3s, you'll need to take a lot of extra pills or oil. So, when buying fish oil, don't focus on the amount of fish oil, but on the amount of omega-3 fatty acids or, better yet, on the amounts of the two key omega-3s, EPA and DHA. This will also show you the ratio of EPA to DHA, which can be important for certain uses.
  • Clinical studies involving herbs typically use herbal ingredients, such as extracts, standardized to provide specific amounts of key natural compounds. But labels often don't provide these details. For example, 200 mg of a turmeric extract may contain as little as 36 mg of curcumin or nearly all of it could be curcumin. A good label will show how concentrated an herbal ingredient is by listing the amount of at least one key compound or its percentage of the total extract or herb. If you don't know what to look for in a specific herb, or the proper dose, ConsumerLab gives you the details in its herbal supplement product reviews.

2. Meaningless claims

Some of the claims that you see on supplements are just meaningless. Common examples are:

  • "Contains clinically tested ingredients"
    This claim is meaningless for many reasons. First, just because an ingredient has been clinically "tested" does not mean it has been clinically "proven" to work. Even if an ingredient has been proven to work, the product may not contain the right amount of ingredient, or suggest the correct dosing. Furthermore, a supplement may contain a combination of ingredients that have never been tested together, so it is not known if the combination will work even if there is good evidence for one or more of its components.

  • Tested by an "FDA Approved Laboratory"
    If a supplement claims to have been tested in an "FDA Approved" laboratory, don't believe it: The FDA does not approve laboratories. However, a laboratory can "register" with the FDA and there are additional meaningful laboratory accreditations. More details are available here.
  • "Pharmaceutical Grade"
    There is no such thing as "pharmaceutical grade" for most supplement ingredients. There is no reason to pay more if you see this meaningless term. However, a manufacturer is allowed to claim that an ingredient meets a standard set by U.S. Pharmacopeial Convention (USP), if such a standard exists. ConsumerLab typically applies USP standards to its testing of supplements.
  • 3. Claims to treat or cure a disease

    Supplements are not legally considered drugs and cannot claim to treat, cure, or diagnose a disease. So be very wary of products that make such claims.

    In specific circumstances where there is significant scientific agreement, claims can be made regarding the ability of a food or supplement to reduce the risk of a disease. These authorized health claims are currently limited, among supplements, to calcium and vitamin D for osteoporosis, folate for neural tube defects, stanols/sterols for heart disease, and soluble fiber (including that from psyllium husk) for heart disease.

    When there is more limited or little scientific evidence, on a case-by-case basis, supplements can make qualified health claims regarding disease risk reduction if these have been reviewed and evaluated by the FDA prior to use and are accompanied by disclaimers regarding the level of scientific evidence. An example is that psyllium husk, based on very limited evidence, may reduce the risk of type 2 diabetes. Another example is that EPA and DHA may reduce the risk of coronary heart disease by lowering blood pressure, based on evidence that is inconsistent and inconclusive.

    Supplements can also make more vague claims as to how they act to maintain the structure or function of the human body, with a disclaimer that the FDA has not evaluated the claim. A manufacturer must have substantiation that the claim is truthful and not misleading and must submit a notification of the claim to the FDA. These types of claims are very common on supplements, but keep in mind that the FDA does not evaluate them or the documentation supposedly behind them.

    4. Getting too much of an ingredient without realizing it

    Supplement labels are not required to disclose when the amount of an ingredient may pose a risk of harm, and most won't disclose this voluntarily. Be wary when a vitamin or mineral is listed at more than 100% of the Daily Value (DV), as this is more than you normally need from your entire diet and it may be too much. The Daily Value is based on the maximum requirement across the general population, but your requirement may be less.

    Upper limits, technically known as Tolerable Upper Intake Levels or ULs, exist for most vitamins and minerals but are not shown on labels. Before taking a vitamin or mineral supplement, be sure that you're not exceeding a UL unless you are treating a deficiency or taking the supplement for some other conditions for which it is medically necessary. You can look up nutritional requirements and limits by age, gender, and life stage on our free table of nutritional requirements.

    5. Uncertain certification

    Even companies that try to do the right thing can make mistakes and not know it. That's why it is important to make sure that a product has been properly tested. It's best if this testing is done by an independent, reputable third party like or others such as USP or NSF. Don't rely on products that simply claimed to be "Quality Tested" or even "Third-Party Tested" if the third party is not identified. Look for certification marks, such as's "Approved Quality" seal that specifies what was being tested.

    Also see our product reviews to learn which products have passed our tests — you'll also see which products failed among those we selected for testing.

    6. High prices — They don't mean better quality

    ConsumerLab's tests frequently show that some of the best quality products are not the most expensive ones. Some of the highest-priced supplements are among those that have failed our testing. Often (but not always), big retailers or wholesalers have very good store-brand products at low cost due to their high volume and ability to hold manufacturers to high standards. Supplements can be expensive, so why pay more than you have to? To help in this regard, ConsumerLab's product reviews include price comparisons we factor cost into the selections of our Top Picks.

    Bottom Line — Buyer Beware

    Before you buy are vitamin or other supplement, check for the red flags above to make sure the product at least promises to give you what you want. While you still can't be sure that what's in the bottle matches what's on the label, you'll have avoided many common problems. To find out what's really a supplement, check ConsumerLab's product reviews.

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    Join the conversation

    November 23, 2021

    This is a helpful article...thanks. One thing I've noticed when shopping for a multivitamin is that many provide way more of various vitamins than you need, especially if you eat food! Because I use a helpful online food diary, I know that taking the multivitamin can easily exceed my recommended daily allowance, and that in itself can cause problems. I often cut my multi vitamins in half as that's all I need.

    November 23, 2021

    Very informative-Thank-you

    November 15, 2021

    I got a women's vitamin from Walgreens, and it caused violent vomiting after each one I lost my last meal. I took it back to the store and they were not interested in the info or giving a refund.

    lou 22042
    November 15, 2021

    What was the name of the product?

    November 14, 2021

    Very through and helpful article. Thank you!

    November 10, 2021

    Why is it a vitamin or mineral dosage is in one large pill or capsule is the same size as a multivitamin/mineral supplement pill or capsule?
    November 18, 2021

    Most vitamins as well as minerals (other than calcium, magnesium, and potassium) take up only a small percentage of the volume of pills, so a multivitamin may be the same size as a single-ingredient supplement.

    November 4, 2021

    excellent article, thank you.

    PATRICIA A23699
    November 4, 2021

    November 11, 2021

    Please see the "Top Picks" section of our Vitamin D Supplements Review, which includes our Top Pick for vitamin D plus calcium,

    November 2, 2021

    If only there were one reliable brand or source for all vitamin and supplement needs.

    November 23, 2021

    Yes, it would be nice

    October 17, 2021

    if you're going to use supplements then having Dr Cooperman on your side is a good idea . thank you doc!

    October 15, 2021

    very helpful and educated article, thanks

    October 14, 2021

    Trying to navigate the maze of supplements is daunting. I try to educate myself and be skeptical of a lot of the claims. Obviously that is why I am a member of Consumer Labs and I have read this article.

    October 11, 2021

    Can't get this sort of solid consumer information anywhere else! Thank you.

    November 19, 2021

    These CL people are a perfect example of dedication to the quality of testing and review for the benefit of anyone really interested in good health. And we have access to their reports and newsletters at a very nominal fee. Thanks for all of your research.

    October 10, 2021

    Great article and info. Thanks!

    October 10, 2021

    There are several reasons I subscribe to ConsumerLab, but "heads up" articles like this one is certainly one of them.

    October 11, 2021

    Yes indeed, ditto!

    October 13, 2021

    Same as the others above me said, that was such a helpful article. Thank you!

    Lou 23543
    October 15, 2021


    October 15, 2021

    This information is invaluable! There is no way we receive the proper nutrition in today's market foods and supplementing has been key to me maintaining my health and energy. I was devastated when I found out my daily vitamin was banned in Europe due to fillers and colors. Placing bad stuff in my body is a horrible feeling. I still havent found a good quality multi-vitamin to replace Centrum, but it is wonderful articles like this one that helps me become educated on every level in the supplement world. Thank you! My favorite and x-physcian that moved away was my best contact for this, so now I depend 100 percent on Consumer Labs and my research here. Thanks for your writing in layman's terms for deciphering.

    October 17, 2021

    I learned something new about Omega 3 supplements. Thanks for the information, very helpful as always.

    October 20, 2021

    Excellent article. Even the Cleveland Clinic suggests checking out information on Consumer Lab. I guess everyone in the know recommends this website! Been a member for years.

    November 3, 2021

    Thanks you Consumer labs, the best subscription on the internet and worth every penny. I am grateful to Doc Cooperman.

    November 15, 2021

    Consumer Labs is the first place I check for my supplement questions.

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