NOW (Bloomingdale, IL) continued its award-winning quality testing program with a survey of 25 different brand samples of methylcobalamin (methyl B12) purchased on Amazon in January 2025.
Methyl B12 was chosen because of its high cost and potential failure of its potency label claim. The results once again identified brands not meeting label claims, but fewer than other supplements NOW tested in the past. All the samples were analyzed using high-performance liquid chromatography (HPLC).
This round of testing highlighted that due to the “inherent complexity” of testing vitamin B12, even third-party testing labs may not be able to produce consistent results, NOW said.
According to NOW, of the 23 brands (not counting NOW’s two products), 11 brands exceeded their label claims with six testing above 120 percent, 12 brands tested below 100 percent with three testing between 90-100 percent and three testing at 0-1 percent potency.
The liquid and gummy forms were less stable and harder to analyze accurately compared to tablets and capsules. Only one product met potency while others ranged from 1 percent to 105 percent, NOW said.
“Testing vitamin B12 is inherently challenging due to the instability of methylcobalamin and the difficulty in obtaining consistent results across various matrices and dosage forms. Contract laboratories often struggle with maintaining standard stability and accurate analyte recovery, contributing to the variability observed in this study. Our internal data highlight the industry’s need for more robust testing methods and quality control measures,” NOW said.
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