Effect of light on vitamin B12 and folate

Background: Laboratory specimens submitted for assessment of vitamin B12 and folate have traditionally been light-protected, although this practice is based on limited data. Methods: This study compared changes in assayed values for B12 and folate from 25 healthy human volunteers when measured at 1, 2, and 7 days with both light-protection and light-exposure. Results: For B12, there was an average decrease of 7.5% at 7 days when light-protected and a 7.7% decrease when lightexposed, while folate showed a 1.7% average decrease when light-exposed and a 1.0% decrease when light-protected. Neither of these values differed significantly between lightexposed or light-protected. Conclusions: This study demonstrates there is no need to light-protect specimens prior to vitamin B12 and folate analysis.