How Daily Values On The Label Are Set

Every packaged food sold in the United States carries percent Daily Values on its Nutrition Facts panel. Those percentages come from a deliberately simplified reference system.

One number for a diverse population

Nutrient requirements vary by age, sex, pregnancy status and body size. A label cannot print a table for each reader, so a single reference value is chosen per nutrient.

For most vitamins and minerals, the Daily Value is based on the highest recommended intake across the adult population groups the label covers. It is intentionally generous rather than average.

The percentage shown is therefore the fraction of that reference figure supplied by one serving. It is not the fraction of any particular reader's requirement.

Where the underlying numbers come from

The recommended intakes behind Daily Values are the Dietary Reference Intakes, developed through expert committee review of nutrition research by the National Academies.

Regulators at the Food and Drug Administration then translate that scientific work into labeling values, which requires rounding, simplification and periodic updating as the underlying reviews change.

Because the two processes run on different schedules, a Daily Value on a label reflects the state of the reference work at the time the labeling rule was set.

Calories are calculated differently

Nutrients tied to energy intake, including total fat, saturated fat, carbohydrate and fiber, are anchored to a two-thousand-calorie reference diet stated at the bottom of many panels.

That figure is a labeling convention rather than a recommendation. Readers who eat considerably more or less should expect their own appropriate amounts to differ proportionally.

Sodium and added sugars work as ceilings rather than targets, so a high percentage there carries the opposite meaning from a high percentage of potassium or iron.

Reading percentages usefully

The conventional rule of thumb treats a low single-digit percentage as a minor contributor and a figure around a fifth or more as a significant one. This applies to a serving, not a package.

Serving sizes on the panel are standardized reference amounts, so comparing two products' percentages is meaningful in a way that comparing them to a personal portion is not.

The panel also has limits. It reports amounts present, not amounts absorbed, which matters for minerals whose availability from plant foods depends on the rest of the meal.

What the panel cannot answer

Labels describe foods individually while intake accumulates across a day and a week. No single panel indicates whether a diet is adequate.

Nutrients of particular interest to people eating mostly plants, including vitamin B12 and vitamin D, are worth tracking through actual intake and, where appropriate, laboratory testing rather than label reading.

Interpreting those results and deciding what follows is work for a physician or a registered dietitian, who can weigh personal history that no reference value accounts for.