Biological Preparation to Assess Folate in Whole Blood and Serum Folate Microbiologic Assay Materials

CDC offers assay materials to laboratories measuring serum or whole blood folate by microbiologic assay.

Target laboratories:

Laboratories engaged in public health work assessing folate status in populations.

Program goals:

Achieve reliable and comparable folate data across laboratories and over time by providing common key reagents to laboratories engaged in public health work assessing folate status in populations.

Featured analytes:

  • Whole blood folate
  • Serum folate

About the Folate Microbiologic Assay Materials

The WHO recommends the microbiologic assay for assessing folate status in population surveys (WHO, 2015) and this assay is amenable for laboratory capacity building in low-resource settings (Pfeiffer et al., 2018). Using common key reagents helps to produce reliable data that are comparable across laboratories and over time (Zhang et al., 2018). CDC offers assay materials containing common key reagents to laboratories conducting the folate microbiologic assay for epidemiologic use.

The frozen assay materials include the following components:

  • Microorganism (Lactobacillus rhamnosus)
  • Calibrator stock solution (5-methyltetrahydrofolate)
  • Quality control materials (2 levels)
  • Reagents (3) needed for the preparation of the growth medium: ascorbic acid, chloramphenicol, and manganese sulfate

Shipping Schedule

Requesting laboratories must be able to receive frozen samples packed in dry ice, retrieve samples from customs at the airport, and pay for any costs required by customs.

Costs of the Folate Microbiologic Assay Materials

Requesting laboratories must enter into a Material Transfer Agreement with CDC prior to receiving materials. Laboratories pay a user fee to cover CDC’s costs for quality assurance materials and biological preparations. Laboratories also pay for material shipping costs.

To request the folate microbiologic assay materials, contact Please include the country and/or laboratory name and “Folate MBA materials” in the subject line. CDC will contact you to facilitate the Material Transfer Agreement.


Pfeiffer CM, Zhang M, Jabbar S. Framework for laboratory harmonization of folate measurements in low- and middle-income countries and regions. Ann N Y Acad Sci 2018; 1414:96–108.

World Health Organization. Guideline: optimal serum and red blood cell folate concentrations in women of reproductive age for prevention of neural tube defect. Geneva, Switzerland: World Health Organization, 2015.

Zhang M, Sternberg MR, Pfeiffer CM. Harmonizing the calibrator and microorganism used in the folate microbiological assay increases the comparability of serum and whole blood folate results in a CDC round-robin study. J Nutr 2018; 807-17.

Page last reviewed: November 20, 2019