Stability of blood (pro)vitamins during four years of storage at −20 °C: Consequences for epidemiologic research

• Published in: Journal of clinical epidemiology Vol. 48; no. 8; pp. 1077 - 1085
• Main Authors: Ocké, Marga C., Schrijver, Jaap, Obermann-De Boer, Gatske L., Bloemberg, Bennie P.M., Haenen, Guido R.M.M., Kromhout, Daan
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1995; Elsevier
• Subjects: Attenuation; Biological and medical sciences; Epidemiology; Frozen storage; General aspects; Medical sciences; Methodology; Plasma; Public health. Hygiene; Public health. Hygiene-occupational medicine; Stability; Vitamins; Whole blood; Whole blood; Plasma; Attenuation; Frozen storage; Stability; Vitamins; Human; Investigation method; Chemical stability; Conservation; Samplings; Vitamin; Epidemiology; Blood; Public health
• ISSN: 0895-4356; 1878-5921
• 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 °C. Dramatic decreases occurred for EDTA-plasma concentrations of vitamin E between 6 and 12 months, vitamin A, total carotenoids and β-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, B
6, B
12 (EDTA-plasma), B
1 and B
2 (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 °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 °C.