Labdoor analyzed 22 best-selling prenatal vitamin supplements in the United States, measuring levels of key vitamins (A, B3, B6, C, D, and folic acid), minerals (calcium, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc), fatty acids (total omega-3, EPA, and DHA), and heavy metals (antimony, arsenic, bismuth, cadmium, lead, and silver).
The relative bioavailabilities of different vitamin and mineral forms factored heavily into this analysis. Prenatal vitamins were penalized for utilizing lesser forms of key active ingredients, such as ergocalciferol (vitamin D2) instead of cholecalciferol (vitamin D3).
Samples of every prenatal supplement passed all six heavy metal assays. Products received reduced Ingredient Safety ratings for the presence of key watchlist ingredients, including three artificial coloring agents (Blue 2, Yellow 6, and Red 40) and two controversial preservatives (butylated hydroxytoluene and benzoic acid).
Average absolute variance ranged from 15.5% (vitamin B3) to 47.2% (vitamin B6) in vitamin content and from 4.5% (iron) to 135% (potassium) in mineral content.
Mineral content fared well, with iron, magnesium and manganese all recording average absolute variances below 10%. Among the vitamins, vitamins A and C were the most likely to fall below their label claims, with 5 products recording 10% less vitamin A than claimed and 3 products recording 10% less vitamin C than claimed.
All 22 prenatal supplements were screened by Inductively Coupled Plasma (ICP)-based techniques for the presence of heavy metals. Samples of every multivitamin passed all six heavy metals assays, indicating that samples contained under 1 PPM (part per million) each of antimony, arsenic, bismuth, cadmium, lead, and silver compounds.
Labdoor’s Nutritional Value calculations are largely based on macronutrient ratios, with added sugars, sodium, and cholesterol also penalized in this rating. Most prenatal vitamins recorded low values across the board here.
19 of 22 tested supplements were listed at under 10 calories per serving. At 3g of sugar and 20 calories per serving, Vitafusion Prenatal Gummies recorded the highest value for both attributes.
Labdoor’s Ingredient Safety calculations are based on two key factors. First, products were penalized when their measured active ingredient values meet or exceed published Tolerable Upper Limits (TUL). Prenatal vitamins also received reduced Ingredient Safety scores based on the presence and severity of key heavy metals and added excipients.
3 prenatal vitamins exceeded the TUL for vitamin B3 (35 mg) in a single serving. 5 products exceeded the TUL of folic acid (1000 mcg) in a single serving.
Mineral content was well below published TUL levels in most prenatal products.
4 of 22 products contained at least one artificial coloring agent (Blue 2, Yellow 6, and/or Red 40). Other flagged watchlist ingredients include carmine, caramel color, titanium dioxide, butylated hydroxytoluene, and benzoic acid, which were each present in at least two products in this category.
Note: All TUL values are those indicated for pregnant women 19-50 years of age.
Labdoor’s Projected Efficacy calculations are based on two key factors. First, we identified the relative bioavailability of each vitamin and mineral form. Then we compared the measured amounts of each active ingredient form in a sample to this standard.
For example, physiologically available Vitamin A (retinol) is measured in Retinol Activity Equivalents (RAE), a metric that accounts for source-dependent vitamin A bioactivity. Preformed Vitamin A, referring to this vitamin’s acetate and palmitate forms, records the highest RAE value (0.3mcg RAE/1 IU). Supplemental beta-carotene, present in 18 of 22 products, is considered to be half as bioavailable (0.15mg RAE/1 IU) as preformed Vitamin A. Dietary carotenoids, present in 2 products, are expected to contribute the least biological efficacy (0.025mcg RAE/1 IU).
Two products were penalized for usage of ergocalciferol (vitamin D2) instead of cholecalciferol (vitamin D3) in their formulations. Clinical studies have established the inferiority of ergocalciferol to cholecalciferol in improving patient nutrient status, determined by measuring serum 25-hydroxyvitamin D levels.
16 of 22 products either met or exceeded the Recommended Dietary Allowances (RDAs) for vitamin A, vitamin B3, and folic acid in a single serving. Additionally, 13 products exceeded the RDA of vitamin B6 and 8 products exceeded the RDA of vitamin C.
11 products included omega-3 fatty acids, primarily focused on DHA, in their formulations. DHA is important to the visual and brain development of fetuses. For women who are chronically deficient in DHA, especially those who may have reduced their seafood intake before or during pregnancy, such supplementation may be beneficial. However, according to a 2010 study published in The Journal of the American Medical Association, DHA supplementation is not expected to provide additional benefits to fetuses already receiving adequate DHA quantities.
Note: All RDA values are those indicated for pregnant women 19-50 years of age.