Ingredient Science: Iron—How to Read the Number on a Supplement Facts Label

On a supplement label, the iron number only makes sense after you read the serving size and the age context.

Start at the top of the panel

FDA rules require a Supplement Facts panel to identify the Serving Size and list the amount of each dietary ingredient per serving. That means an iron amount is tied to the stated serving—not automatically to one drop, one teaspoon or one tablet unless the label says so.

The percent Daily Value (%DV) shows how much a nutrient in one serving contributes relative to the applicable FDA Daily Value. It is a reference for interpreting the label; it is not a personalized prescription for every child.

Then look at form and total intake

Iron can appear in different chemical forms, and food provides iron too. NIH distinguishes heme iron from animal foods and nonheme iron from plant foods and fortified foods. The body absorbs these forms differently, and vitamin C can improve absorption of nonheme iron.

When comparing products, read the amount per serving, serving size, age directions and all other sources of iron. A larger number is not automatically a better fit.

Educational information only. Do not combine iron-containing supplements for a child without considering total intake and the child's clinical circumstances.