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Analyses Performed

75 analytical tests on 13 of the best-selling vitamin B12 supplements in the United States.
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Must-see Statistic

Measured vitamin B12 content ranged from 515 mcg to 6990 mcg per serving.

Unconventional Wisdom

Measured vitamin B12 content ranged from -21% to +74% as compared to product label claims.

Testing Summary

Labdoor analyzed 13 of the best-selling vitamin B12 (cobalamin) supplements in the United States for active ingredient content and heavy metal (arsenic, cadmium, lead, mercury) contamination.

Overall, vitamin B12 measurements in this batch analysis ranged from 515 mcg to 6990 mcg per serving, deviating from label claims by an average of 27%. 3 products also recorded vitamin B6 and/or vitamin B9. 9 of the 13 products recorded more vitamin B12 than claimed, with one product recording as much as 74% of its label claim for vitamin B12. All products passed heavy metal screenings, and recorded vitamin B12 levels considered to be safe by the Institute of Medicine (IOM)1.

Analytical Chemistry Methods: LC-UV/VIS (vitamin B12), CE (vitamin B6), ICP-OES (vitamin B9), ICP-MS (arsenic, cadmium, lead, mercury).

Label Accuracy

Small bottle with magnifying glass 9 of 13 products deviated 10% or more from their label claims for vitamin B12 content.

Measured vitamin B12 in this batch analysis deviated from label claims by an average of 27%. 9 of the 13 products measured more vitamin B12 than claimed, recording an average overage of 30%. Products measure vitamin B12 anywhere from -21% to +74% vs. products' label claims.

Product Purity

Microscope All 13 products passed heavy metal screens for arsenic, cadmium, lead, and mercury.

All products passed heavy metal screens. This means that each product's heavy metal recordings per serving fell below California Proposition 65's2 proposed and established MADLs (Maximum Allowable Dose Levels) and NSRLs (No Significant Risk Levels): no more than 10 mcg/day of inorganic arsenic, 4.1 mcg/day of cadmium, 0.5 mcg/day of lead, and 0.3 mcg/day of mercury (proposed).

Nutritional Value

Fruits Vitamin B12 products averaged a 100 (out of 100) in Nutritional Value scores.

Vitamin B12 products in this batch recorded minimal quantities of calories, fats, carbohydrates, and sugars.

Ingredient Safety

Caution sign No flagged artificial sweeteners, colors, or preservatives were recorded in this batch analysis.

Currently, there is no established Tolerable Upper Intake Limit (UL) for vitamin B12. According to the Institute of Medicine (IOM), "no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals." However, vitamin B12 has the potential to interact with certain medications1. Please consult your physician before supplementation, especially if you have a medical condition, are pregnant, or are taking any other drugs or dietary supplements.

Sucralose, an artificial sweetener, was recorded in one product in this batch, Kirkland Signature Quick Dissolve B12.

Projected Efficacy

Line with arrow going up On average, products measured 2183 mcg of vitamin B12 per serving.

Vitamin B12 content averaged 2183 mcg per serving, ranging from 515 mcg in Nature Made B-12 500 mcg tablets to 6990 mcg in Nature's Bounty Super Strength Liquid B-12. Serving sizes are not standardized. 4 products recorded less than 1000 mcg of vitamin B12 per serving. 3 products recorded more than 4000 mcg of vitamin B12 per serving.

Vitamin B12 is essential for proper red blood cell production, neurological and cognitive function, and DNA synthesis. Symptoms of deficiency include anemia, fatigue, nervous system changes, and cognitive decline. Outside of supplementing for otherwise deficient intake, vitamin B12 is often taken to prevent cardiovascular disease, improve cognitive functioning, or increase energy. However, clinical research has not yet been able to substantiate these claims1.

Recommended Daily Allowances (RDA) for vitamin B12 are 2.4 mcg for men and women, 2.6 mcg and 2.8 mcg for women if pregnant or breastfeeding, respectively. Older adults, vegetarians, and people with certain medical conditions may need more vitamin B12 to compensate for diets low in vitamin B12 and/or difficulty absorbing vitamin B121. Please consult your physician for specific dosing.


  • 1NIH. (2016). Vitamin B12 Dietary Supplement Fact Sheet.
  • 2CA OEHHA. (2016). Proposition 65.