How to read a supplement label

A supplement label is a regulated document with a sales pitch printed around it. Once you know which parts are required by law and which are marketing, the shelf gets easier to read.

The Supplement Facts panel

A product sold as a dietary supplement must say so on the front and carry a Supplement Facts panel. The FDA lists what it has to show: the serving size, the servings per container, every dietary ingredient, and the amount of each per serving. Everything else in the formula goes in a separate “Other ingredients” list, and the label must name the manufacturer, packer or distributor and give a domestic contact for reporting a problem. Every number is per serving, and a serving can be more than one capsule.

Daily Values are the FDA's reference amounts of nutrients to consume, or not to exceed, each day. The % Daily Value tells you how much of that reference one serving supplies, and supplement labels use the same system as food labels: 5% DV or less per serving is low, 20% DV or more is high. An ingredient with no established Daily Value shows an amount but no percentage, so the panel cannot tell you whether that amount is large or small.

What the FDA does, and does not, do

The FDA does not approve dietary supplements for safety or effectiveness before they are sold, and it does not approve their labels. The company is responsible for making sure its products are safe and truthfully labeled; only a product with a new dietary ingredient has to be flagged to the FDA in advance. The agency's work begins once a product is on the market: it inspects facilities, monitors adverse event reports, reviews labels and websites for disease claims, and can request recalls. It does not routinely test what is in the bottle.

• If a product makes you ill, contact your health care provider first; either of you can then report it through the FDA's Safety Reporting Portal.
• A third-party seal such as USP verification says the bottle contains what the label states, without contamination. That is a statement about contents, not about whether the product does anything for you.

Structure/function statements and the disclaimer

A supplement label may not claim to diagnose or act against a disease. What it may carry is a structure/function statement, describing an effect on the body's normal structure or function. The company must hold evidence that it is truthful and not misleading, but nobody outside the company reviews that evidence before sale. That is why every such statement sits beside a fixed disclaimer: the Food and Drug Administration has not evaluated it, and the product is not intended to diagnose or act on any disease. The disclaimer is the label telling you, accurately, who has and has not checked the claim.

“Natural” is not a safety rating

The FDA says plainly not to assume that the word “natural” means a product is safe. NCCIH's examples: kava may cause severe liver damage, and ephedra was banned in 2004 after being associated with heart problems and risk of death. Supplements can also interact with medicines, interfere with lab tests, cause dangerous effects during surgery, and be harmful in high amounts or over long use; many have never been tested in pregnant women, nursing mothers or children.