What Counts as a Dietary Supplement?

The category is broader than most people realize. Under U.S. law, a dietary supplement is any product taken by mouth that contains a "dietary ingredient" intended to supplement the diet. That umbrella covers:

  • Vitamins (e.g., vitamin D, vitamin C, B12)
  • Minerals (e.g., magnesium, zinc, iron)
  • Herbal or botanical ingredients (e.g., echinacea, turmeric, valerian root)
  • Amino acids (e.g., glutamine, lysine)
  • Enzymes and other compounds (e.g., probiotics, omega-3 fatty acids)

They come in capsules, tablets, softgels, powders, liquids, and even some bars — but only when labeled as a supplement. What they are not is food in the conventional sense, and they are not drugs. This middle-category status has significant consequences for how they're regulated and what claims can legally appear on their labels.

For context on which vitamins and minerals many Americans actually lack from food alone, see our article on common micronutrient shortfalls.

How the FDA Regulates Supplements — and What That Doesn't Cover

The key law governing supplements in the United States is the Dietary Supplement Health and Education Act (DSHEA) of 1994. It fundamentally shifted the regulatory burden: rather than requiring manufacturers to prove a product is safe before selling it, the FDA must demonstrate a product is unsafe to remove it from the market.

57%

U.S. adults who report taking a dietary supplement

According to the National Institutes of Health Office of Dietary Supplements, more than half of American adults use at least one dietary supplement.

~90,000

Supplement products estimated on the U.S. market

The FDA has estimated that tens of thousands of distinct supplement products are available to U.S. consumers, a figure that has grown substantially since DSHEA passed in 1994.

Post-market

Stage at which FDA typically intervenes on safety

Under DSHEA, the FDA generally cannot remove a supplement from sale until it can demonstrate the product poses an unreasonable risk — a burden that applies after, not before, the product reaches consumers.

In practical terms, this means:

  • No pre-market approval is required for most supplements.
  • Manufacturers are legally responsible for ensuring product safety, but independent verification before sale is not mandated.
  • The FDA can take action after the fact — issuing warnings, ordering recalls — but typically only after adverse events are reported.

Manufacturers are required to follow Current Good Manufacturing Practices (CGMPs), which set standards for production, labeling, and quality control. However, the FDA's capacity to inspect every facility regularly is limited. The result is a market where product quality can vary significantly between brands and even between batches.

New Ingredients Require FDA Notification

There is one important pre-market requirement: if a manufacturer wants to use a dietary ingredient that was not marketed in the U.S. before October 15, 1994, they must submit a New Dietary Ingredient (NDI) notification to the FDA at least 75 days before going to market. This allows the FDA to object if the evidence of safety is insufficient. However, enforcement of this requirement has been inconsistent.

Label Claims: What's Allowed and What Isn't

Supplement labels operate under specific rules about what can and cannot be stated. There are three main claim categories:

Structure/Function Claims
Permitted. These describe how a nutrient or ingredient may affect a normal body function (e.g., "calcium builds strong bones," "fiber maintains digestive health"). They must be accompanied by a disclaimer that the FDA has not evaluated the claim and that the product is not intended to diagnose, treat, cure, or prevent any disease.
Disease Claims
Not permitted on supplements. Stating that a product treats, prevents, or cures a specific disease automatically reclassifies it as a drug — subject to full pharmaceutical review.
Nutrient Content Claims
Permitted under certain conditions (e.g., "excellent source of vitamin C"), governed by FDA definitions.

Understanding these distinctions is useful when reading labels. Language like "supports heart health" is a structure/function claim — it is not equivalent to evidence that the product prevents heart disease. Our nutrition terms glossary can help decode other common label language.

How to Approach Supplements as an Informed Consumer

Given the regulatory landscape, a few practical principles can help consumers navigate the supplement aisle more confidently.

A Food-First Approach Is Usually Preferred

Most nutrition experts and public health guidelines suggest getting nutrients primarily from a varied, balanced diet rather than supplements. Whole foods deliver nutrients alongside fiber, phytonutrients, and other compounds that supplements typically cannot replicate. Supplements may be appropriate for specific deficiencies or life stages — but that determination is best made with a healthcare provider.

Look for third-party verification. Organizations such as USP (United States Pharmacopeia), NSF International, and ConsumerLab independently test supplements to verify that products contain what their labels claim and are free from common contaminants. A seal from one of these bodies is a meaningful — though not infallible — quality signal.

Tell your healthcare provider. Supplements can interact with prescription medications and may not be appropriate for everyone. This is especially important for people who are pregnant, nursing, elderly, or managing chronic conditions. A qualified provider can assess whether a specific supplement makes sense for your individual circumstances.

Be skeptical of dramatic claims. If marketing language promises rapid, dramatic, or cure-like outcomes, that's a signal to scrutinize the evidence. The research base for many popular supplements is preliminary, mixed, or limited to specific populations.

If your interest in supplements stems from concerns about gaps in your diet, exploring plant-based dietary approaches or other food-first strategies may also be worth discussing with a provider.

This article provides general health information and education only. It is not medical or dietary advice. Consult a qualified healthcare professional before making decisions about supplements or your individual health needs.