Why potassium is on a food label and phosphorus usually is not
The words below are the regulation's own. They are quoted exactly from the United States Code of Federal Regulations.
The definition
The declaration of vitamins and minerals as a quantitative amount by weight and percent of the RDI shall include vitamin D, calcium, iron, and potassium in that order, for infants through 12 months, children 1 through 3 years of age, pregnant women, lactating women, and adults and children 4 or more years of age, except quantitative weights for these vitamins and minerals are not required for labels described in paragraph (j)(13) of this section.
The declaration of vitamins and minerals in a food, as a quantitative amount by weight and percent of the RDI, may include any of the other vitamins and minerals listed in paragraph (c)(8)(iv) of this section.
The declaration of vitamins and minerals shall include any of the other vitamins and minerals listed in paragraph (c)(8)(iv) of this section as a statement of the amount per serving of the vitamins and minerals as described in this paragraph (c)(8)(ii), calculated as a percent of the RDI and expressed as a percent of the Daily Value, when they are added as a nutrient supplement, or when a claim is made about them, unless otherwise stated as quantitative amount by weight and percent of the Daily Value.
Plain facts about this rule
Phosphorus is one of the “other vitamins and minerals listed in paragraph (c)(8)(iv)”. So a maker may print it, and must print it in the two cases the third quote names. Otherwise the label need not show it.
When a label shows no phosphorus figure, the amount is unknown from the label. It does not mean there is none.
Added phosphates are named in the ingredient list on a pack. The amount of phosphorus they add usually is not.
To look for these words in an ingredient list, use Check a label.
Source
- Text used:
- Electronic Code of Federal Regulations (eCFR), Title 21, Part 101, as in force on 6 October 2026
- Checked on:
- 11 October 2026