Reading a Mineral Supplement Label: Elemental Amounts, Percent Daily Value, "As" Forms and Added Ingredients

What this page covers

This page explains how a US mineral supplement label is built and what each part tells you. It describes US rules from the FDA; labels in the UK, EU and Canada follow other rules, which this page does not describe. A label tells you what the maker says is in a serving. It cannot tell you whether the product is right for you, which is a question for a clinician or pharmacist. For the general guide, see Reading supplement labels.

The Supplement Facts panel

Supplement labels use a "Supplement Facts" panel rather than a "Nutrition Facts" panel. It lists serving size, servings per container, and the amount of each dietary ingredient per serving. [1] The FDA says the Supplement Facts label must list the same nutrients as the Nutrition Facts label when any of them is present in an amount greater than zero. [2] Vitamins and minerals are listed in a set order, and the minerals run calcium, iron, phosphorus, iodine, magnesium, zinc, selenium, copper, manganese, chromium, molybdenum, chloride, sodium, potassium. [1]

Ingredients without a Daily Value are listed too, marked with a symbol that points to a footnote reading "Daily Value Not Established". [1]

Elemental amounts

The panel shows the weight of the mineral, not of the compound that supplies it. The FDA guide says that when calcium carbonate supplies calcium, the panel must list the weight of calcium rather than the weight of the calcium carbonate. [1] Units follow the Daily Value units, for example milligrams for calcium and micrograms for iodine. [1][2] If you are comparing a figure on a web page with a figure on a label, check which is meant; see mineral units and conversions.

"As" forms and the source of a mineral

The guide says a maker may list the source of a dietary ingredient in the panel, for example the specific salt, and need not repeat it in the ingredient statement when it is already in the panel. [1] So "magnesium (as magnesium oxide)" is a normal way to show the form. Different forms behave differently in the body, which the form pages cover; see mineral supplement forms. The label does not say how well a form is absorbed.

Percent Daily Value (%DV)

The %DV is the share of the Daily Value that one serving provides. [1] The FDA's own example: if the Daily Value is 300 mcg and a serving has 30 mcg, the %DV is 10%. [2] As a general guide the FDA says 5% DV or less per serving is low and 20% DV or more is high. [2]

Current Daily Values (adults and children 4 and older) from the FDA reference guide dated August 2023: [2]

A Daily Value is a label reference figure, not a personal requirement. Other Daily Values apply to infants, children under 4, and pregnant or lactating women, and on those labels the FDA guide says percentages for selenium, manganese, chromium, molybdenum, chloride, sodium and potassium must not be listed. [1]

A Daily Value is not an upper limit

Two different numbers are easy to confuse. The Daily Value is a label yardstick. An upper level is a published ceiling set separately for each mineral, age group, country and, often, for supplements only. Compare the two for adults:

The figures differ because the bodies used different evidence and definitions. The NHS wording is guidance on supplement amounts not expected to cause harm, not a suggestion to take that amount. The NHS also says high iron doses (over 20 mg) can cause constipation, sickness and stomach pain. [5] A product can sit at 100% of a Daily Value and a person can still pass one body's upper level by adding other products, so read the actual milligram or microgram figure and the serving size, and add up everything taken. See mineral toxicity and upper limits.

Other ingredients, blends and salt

• Binders and fillers. The FDA guide says ingredients that are not dietary ingredients, such as binders, excipients and fillers, go in the ingredient statement below the panel; a magnesium salt used as a binder is listed there. [1]
• Proprietary blends. A blend is shown with its total weight and its contents in descending order by weight, while dietary ingredients that have a Daily Value must be listed separately with their own weights. [1]
• Sodium. The NHS says some dissolvable tablets, including vitamins, may be high in salt. [8]
• Claims. A statement such as "Calcium builds strong bones" is a structure/function claim and must carry a disclaimer that the FDA has not evaluated it. Labels cannot claim to diagnose, treat, cure, mitigate or prevent a disease. [9]

How reliable is the label?

By FDA guidance, a nutrient a maker adds must be present at 100% of the declared amount, while a naturally occurring nutrient must be at least 80%. [1] But NCCIH notes that the FDA can act against misbranded supplements only after they are on the market, and that what is on the label may not be what is in the product. [9] Independent testing programs are described on Quality testing and certifications, and general formula checks on How to evaluate a supplement formula.

Before you buy or start

MedlinePlus advises telling your health care provider about any supplements you use, not taking a bigger dose than the label recommends, and checking with your provider before any type of surgery. [10] NCCIH adds that many supplements have not been tested in pregnant women, nursing mothers or children, and that certain supplements may increase bleeding risk or affect the response to anesthesia. [9] See medicine interactions. If a child swallows a mineral supplement, call Poison Help (US) at 1-800-222-1222, or 911 if the child is unwell.