One new element introduced to the nutrition facts panel under FDA's new regulations is the declaration of quantitative amounts for vitamins and minerals (in addition to the existing percent daily value) at the bottom of the panel. On the surface, this seems pretty straightforward but once you start applying it, you quickly realize that it's not so simple. Values presented on the nutrition facts are always rounded based on rules provided in the regulations. For the vitamins and minerals, the updated 21 CFR 101.9 provided the following rule for rounding of the quantitative amount:
“The quantitative amounts of vitamins and minerals, excluding sodium, shall be the amount of the vitamin or mineral included in one serving of the product, using the units of measurement and the levels of significance given in paragraph (c)(8)(iv) of this section, except that zeros following decimal points may be dropped, and additional levels of significance may be used when the number of decimal places indicated is not sufficient to express lower amounts (e.g., the RDI for zinc is given in whole milligrams, but the quantitative amount may be declared in tenths of a milligram).”
Paragraph (c)(8)(iv) of the final regulation presents a table of Reference Daily Intake (RDI) values for all vitamins and minerals that are permitted to be declared in the nutrition panel. Looking at the table, you will note a variety of units being used to report the different nutrient values and a range of absolute numerical values from 0.9 for copper to 4700 for potassium. So how will you determine what is considered to be significant?
Let’s take a look from the perspective of the daily value. When under 10% of the daily value, the %DV is rounded to the nearest 2%. Since copper has an RDI of 0.9mg, at 2% it would have an amount of 0.018, 4% would be 0.036, 6% would be 0.054, 8% would be 0.072 and 10% would be 0.09. So for copper, it may be necessary to declare the quantitative amount out to the hundredths place or even the thousandths place to get an accurate %DV. If we were to round to the nearest 0.1, the daily value for low levels of the nutrient would be 0% or 10% with nothing in between! If the unrounded amount was used for the percent daily calculation but the quantitative amount was rounded to 0.1 for the declaration, the %DV could range from 2% to 15%, a possibility of 6 different percent daily values. This would be confusing for the consumer.
For potassium, 2% would be 94, 4% would be 188, 6% would be 282, 8% would be 376 and 10% would be 470. So for every 2% increase in the daily value, the amount increases by 94. Declaring potassium to the ones place or even possibly the tens place doesn’t seem to be necessary.
So, do you have to go through the entire list and run these calculations for each nutrient? Luckily, FDA has done the hard work already. In January 2017, FDA provided a guidance document which includes a table with recommended rounding rules for all of the vitamins and minerals permitted to be listed in the nutrition facts panel. Although the rounding of the quantitative amounts using the provided ranges is not mandatory, it provides a consistent approach to help reduce consumer confusion and also to provide a standard when more than one person is calculating nutrition for a company’s products.
In the text of the guidance, FDA mentions that for dietary supplements, vitamin and mineral values that are present at less than 2% of the daily value must be declared as zero for both the quantitative amount and the percent daily value. Currently, quantitative amounts at this level may be declared in the nutrition panel but FDA recommends that food products also follow this rule for even greater consistency.