Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk

Hunt, Shannon E.; Netting, Merryn J.; Sullivan, Thomas R.; Best, Karen P.; Houghton, Lisa A.; Makrides, Maria; Muhlhausler, Beverly S.; Green, Tim J.

doi:10.3390/nu12051283

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Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk

by

Shannon E. Hunt

^1,2,

Merryn J. Netting

^2,3

,

Thomas R. Sullivan

^2,4,

Karen P. Best

^2,3

,

Lisa A. Houghton

⁵,

Maria Makrides

^2,3

,

Beverly S. Muhlhausler

^2,6 and

Tim J. Green

^2,3,*

¹

School of Agriculture, Food and Wine, Faculty of Sciences, University of Adelaide, Adelaide 5005, South Australia, Australia

²

Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide 5000, South Australia, Australia

³

Adelaide Medical School, University of Adelaide, Adelaide 5005, South Australia, Australia

⁴

School of Public Health, University of Adelaide, Adelaide 5005, South Australia, Australia

⁵

Department of Human Nutrition, University of Otago, Dunedin 9016, New Zealand

⁶

Nutrition and Health, Health and Biosecurity Business Unit, Commonwealth Scientific and Industrial Research Organisation, Adelaide 5000, South Australia, Australia

^*

Author to whom correspondence should be addressed.

Nutrients 2020, 12(5), 1283; https://doi.org/10.3390/nu12051283

Submission received: 24 March 2020 / Revised: 24 April 2020 / Accepted: 28 April 2020 / Published: 1 May 2020

(This article belongs to the Section Nutrition and Public Health)

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Abstract

In 2009, the Australian government mandated the addition of folic acid to bread flour to reduce the incidence of neural tube defects (NTD)-affected pregnancies. In 2011–2012, the Australian Health Measures Survey (AHMS) reported a mean red blood cell (RBC) folate in women of reproductive age (16–44 y) of 1647 nmol/L. Over 99% of women had an RBC folate ≥ 906 nmol/L, a concentration consistent with a very low risk of NTDs if a woman became pregnant. However, RBC folate was measured using an immunoassay, which is not a recommended method due to questionable accuracy. The microbiological assay is the preferred method for RBC folate measurement. To determine whether the immunoassay method may have led to spurious conclusions about the folate status of Australian women, we collected fasting blood samples from 74 healthy non-pregnant, non-lactating women (18–44 y) and measured RBC folate using both the immunoassay and microbiological methods. Mean RBC folate (95% confidence interval) concentration measured with the immunoassay method was 1735 (1666, 1804) nmol/L compared with 942 (887, 1012) nmol/L using the microbiological method. No woman had an RBC folate < 906 nmol/L using the immunoassay method, whereas 46% of women had an RBC folate < 906 nmol/L using the microbiological method. The NTD risk was estimated to be 0.06% using the immunoassay method and 0.14% using the microbiological method. RBC folate using AHMS survey may have underestimated NTD risk in Australian women.

Keywords: red cell folate; microbiological assay; immunoassay; folate measurement; neural tube defects

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MDPI and ACS Style

Hunt, S.E.; Netting, M.J.; Sullivan, T.R.; Best, K.P.; Houghton, L.A.; Makrides, M.; Muhlhausler, B.S.; Green, T.J. Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk. Nutrients 2020, 12, 1283. https://doi.org/10.3390/nu12051283

AMA Style

Hunt SE, Netting MJ, Sullivan TR, Best KP, Houghton LA, Makrides M, Muhlhausler BS, Green TJ. Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk. Nutrients. 2020; 12(5):1283. https://doi.org/10.3390/nu12051283

Chicago/Turabian Style

Hunt, Shannon E., Merryn J. Netting, Thomas R. Sullivan, Karen P. Best, Lisa A. Houghton, Maria Makrides, Beverly S. Muhlhausler, and Tim J. Green. 2020. "Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk" Nutrients 12, no. 5: 1283. https://doi.org/10.3390/nu12051283

APA Style

Hunt, S. E., Netting, M. J., Sullivan, T. R., Best, K. P., Houghton, L. A., Makrides, M., Muhlhausler, B. S., & Green, T. J. (2020). Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk. Nutrients, 12(5), 1283. https://doi.org/10.3390/nu12051283

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Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk

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