What does "%DV" (Daily Value) mean on a supplement label, how does it differ from RDAs, and should anyone take more than the DV for a nutrient?

Answer:

The DVs (Daily Values) are set by the Food and Drug Administration (FDA) and describe the recommended amount of nutrients to consume each day from the entire diet (including any supplement) based on a 2,000-calorie diet. The "%DV" shown on labels in Nutrition Facts and Supplement Facts panels shows how much a single serving of a particular food or supplement contributes to the DV of a nutrient. For example, the DV for iron for adults is 18 mg, so if a supplement contained 10 mg of iron per serving, the %DV for iron would be 56%.

Continue reading to find out how DVs differ from RDAs (Recommended Dietary Allowances) and whether any group of people should consume more than the DV for a nutrient.

What is the difference between DV and RDA?

Unlike DVs, which are set by the FDA, the RDAs (Recommended Dietary Allowances) for vitamins and minerals are developed by the National Academies. RDAs describe the average daily intake levels of essential nutrients that are considered to be adequate to meet the nutritional needs of nearly all healthy people. Compared to DVs, RDAs may be more specific to age, gender, and life stage.

The DVs are based on the RDAs but, sometimes, are not up to date. Until the FDA updated the DVs in 2016, many DVs (which were originally set in 1968) did not necessarily reflect the latest intake recommendations and did not carefully distinguish needs by age and gender — there was just one DV established for each vitamin and mineral for all healthy adults and children age 4 and over. Since updated in 2016, the DVs more closely reflect the RDAs and include separate DVs specifically for infants, children 1 to 3 years of age, and pregnant/lactating women, in addition to the original category of all healthy adults and children age 4 and over. The new DVs for this last category of people are now generally based on the highest RDA for this population.

Unlike DVs, the RDAs do not typically appear on food and supplement labels.

For the most current RDAs and DVs, as well as Upper Limits, for vitamins and minerals, see ConsumerLab.com's Recommended Daily Intakes and Upper Limits for Nutrients.

Should anyone take supplements with more than the DV for a nutrient?

In general, it's best to avoid an excessive dose of any vitamin or mineral if it is not needed. Some vitamins and minerals are likely safe to take at doses higher than the DV, but they may still cause side effects or interfere with certain laboratory tests. For example, no tolerable upper intake level (UL) has been established for vitamin B-12, but taking approximately 8 times the DV for this vitamin can cause acne and rosacea, and taking very high doses (about 208 times the DV) has been linked with increased risk of colorectal cancer. High doses of biotin can cause misleading results in a number of laboratory tests.

Furthermore, some vitamins and minerals have a UL that is close to the DV, so taking somewhat more than the DV may increase the risk of side effects. For example, the DV for niacin is 16 mg, while the UL is 35 mg, meaning that taking a supplement containing just twice the DV would come close to exceeding the UL for this nutrient and possibly cause adverse effects. Similarly, the DV for zinc is 11 mg, while the UL is 40 mg, so taking 400% DV as a supplement would exceed the UL.

A special situation exists with magnesium: It's fine to get the DV for magnesium from food, but taking that much from a supplement can cause diarrhea, so the UL for magnesium for supplements is actually lower than the DV.

However, in some situations people may need more than 100% DV of certain nutrients. For example, iron supplements designed for treating iron deficiency generally exceed the DV (and even the UL) for iron, but it would be acceptable take these supplements under a doctor's supervision if you are deficient, as the possible consequences of untreated iron deficiency can be more severe the side effects of excess iron. Vegetarians may require as much as 50% more of the RDA for zinc (which is the same or close to the DV for zinc) due to phytates in legumes and grains that can interfere with zinc absorption. People who are elderly may require intake of certain nutrients that is higher than the DV due to impaired intestinal absorption that can occur with aging (Woudstra, Best Pract Res Clin Gastroenterol 2002). Exercise among elite athletes can increase nutrient requirements to amounts greater than the DV, although athletes often have higher energy intake than the general population, and this higher energy intake often corresponds to increased intake of vitamins and nutrients to account for the greater nutrient requirements (Carlsohn, Dtsch Z Sportmed 2020).