Stability of blood (pro)vitamins during four years of storage at -20 degrees C: consequences for epidemiologic research

J Clin Epidemiol. 1995 Aug;48(8):1077-85. doi: 10.1016/0895-4356(94)00232-f.


We studied the effects of frozen storage on (pro)vitamin concentrations in EDTA-plasma and whole blood. Aliquots from 55 samples were analyzed before storage and after 3, 6, 12, 24, 36 and 48 months at -20 degrees C. Dramatic decreases occurred for EDTA-plasma concentrations of vitamin E between 6 and 12 months, vitamin A, total carotenoids and beta-carotene after 1 year, and whole blood niacin. A smaller decrease was observed for folic acid at 1 year of storage, but the level remained constant thereafter. The vitamins D, B6, B12 (EDTA-plasma), B1 and B2 (whole blood) showed no decline during 4 years of storage. With the exception of folic acid, the observed decreases varied considerably among subjects. Therefore using EDTA-plasma stored longer than 1 year at -20 degrees C will result in highly attenuated odds ratios when assessing the relationship between vitamin A, carotenoids, or vitamin E with a given disease. Attenuation will also occur when using niacin concentrations in whole blood stored for 4 years at -20 degrees C.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Preservation*
  • Case-Control Studies
  • Confidence Intervals
  • Cryopreservation*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Odds Ratio
  • Time Factors
  • Vitamins / blood*


  • Vitamins