Dietary Supplement Myths You Need to Know

They may not be as effective (or necessary) as we’ve been led to believe.


In a 2019 poll, 86 percent of Americans surveyed said they took some kind of vitamin, mineral, or other dietary supplement. Ironically, data are clear that the benefits of most supplements appear to be minimal at best. Let’s take a look at a few common myths and misconceptions about nutrient supplements:

Myth 1: Everyone can benefit from at least a multi-vitamin/mineral supplement.

Most people in the U.S. already get the major vitamins and minerals they need from their regular dietary intake.

Although many Americans fall short on ideal intake of calcium, vitamin D, and potassium, outright deficiency is rare. Shifts in your diet are a better choice than adding a dietary supplement. “In addition to vitamins and minerals, minimally processed foods contain compounds which likely have beneficial health effects—and there’s no evidence these benefits can be packaged in a pill,” says Alice H. Lichtenstein, DSc, director of the Cardiovascular Nutrition Laboratory at the Human Nutrition Research Center on Aging and executive editor of Tufts Health & Nutrition Letter.

Even common vitamin and mineral supplements may not be as necessary or helpful as we think they are. Two of the most commonly used supplements are vitamin D and calcium. The U.S. Preventative Services Task Force found insufficient evidence for the effectiveness of vitamin D and calcium for bone health in generally healthy women or men. In postmenopausal women (who often take these supplements to help maintain strong bones) the task force concluded that “daily supplementation with 400 IU or less of vitamin D combined with 1000 mg or less of calcium has no effect on the incidence of fractures.” (See page 2 for more on vitamin D.)

Mythbusting advice: Instead of buying supplements, focus on consuming fruits, vegetables, nuts, seeds, beans, whole grains, dairy, and fish and limiting sodium, added sugars, refined grains, and processed meats. Include calcium sources like yogurt, cheese, and milk (or dairy substitutes with added calcium and vitamin D), and omega-3 sources like fish and seafood. If lab tests indicate you are low in a particular nutrient, follow your healthcare provider’s advice for dietary changes and any supplement intake.

Myth 2: Supplements that make it to market have been proven safe and effective.

Prescription drugs and over-the-counter medications have to be proven safe before they go on the market. In contrast, a dietary supplement can go to market without testing, and we don’t really know if it is safe until enough people have taken it for long enough to notice, report, and pool together side effects, were they to occur. For example, supplements containing the plant extract ephedra led to more than 16,000 reported adverse events in the U.S.—including heart attacks, seizures, strokes, and sudden death—before it was banned by the U.S. Food and Drug Administration (FDA) in 2004.

Likewise, supplements do not have to prove they do what they say they do (nor even that they contain the ingredients they claim to contain). While FDA rules prohibit supplements from claiming to treat or prevent a disease, manufacturers can still make bold claims, such as that their products improve energy or immune function or help with weight loss—without having to offer proof. (Legally, labels making unsubstantiated claims should list that these statements “have not been evaluated by the FDA.”) As far as ingredients go, independent testing of dietary supplements frequently finds more or less of an ingredient than indicated on the label and ingredients not listed at all. Some products have even been found to contain dangerous contaminants like heavy metals.

Mythbusting advice: Remember—if something seems too good to be true, it probably is. If you are advised to take a supplement by your healthcare provider, look for products that have undergone third-party testing. This means an independent company (not affiliated with the manufacturer) has tested the product and confirms it contains the ingredients it claims to contain (although it still doesn’t ensure the product will have health benefits). Look for seals from companies like NSF International, United States Pharmacopeia, Informed-Choice, and ConsumerLab, or go to their websites for lists of products that have been tested and approved.

Some dietary supplements may alter the effect of medications, so it’s important your healthcare providers know what you are taking. Make sure they are aware of all supplements you currently take before prescribing a new medication or scheduling a medical procedure.

Myth 3: More is better.

“Once we meet our body’s nutrient requirements, additional intake of any nutrient is not going to be beneficial,” says Lichtenstein. “In fact, excessive intake of certain nutrients can have detrimental effects.” Some nutrients (notably vitamins A and D) are stored in the body and can build up to potentially dangerous levels. High levels of vitamin C can interfere with the body’s ability to absorb copper (and may cause stomach aches and diarrhea); too much phosphorous can inhibit the absorption of calcium; and vitamin B6 toxicity can lead to nerve damage.

Mythbusting advice: Talk to your healthcare provider to make sure you need a supplement before deciding to take one. As safe and “natural” as many supplements may appear to be, consuming nutrients in their natural form—in real, whole foods—is nearly always the better option. “For most supplements, your dollars would be better spent on buying healthy food,” says Dariush Mozaffarian, MD, DrPH, dean of the Friedman School and editor-in-chief of Tufts Health & Nutrition Letter. “Among the world of supplements, the evidence is probably strongest for fish oil [omega 3s], but even there the science for benefits is not conclusive.”

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  1. Thank you. People should remember that nutrients in plant foods work together in a synergistic manner and isolating a single nutrient may not help and even cause harm such as beta carotene.


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