Folate and vitamin B12
Introduction
Vitamin B9 (folate) and vitamin B12 are two essential nutrients with important functions in the body. Folate is essential for the formation of DNA, and without it, cells cannot divide. The need for folate is higher when the body is making new cells, such as during pregnancy (NHMRC 2013a). Vitamin B12 is an essential nutrient that is needed for making red blood cells, the production of DNA and maintenance of the nervous system. Vitamin B12 is important for folate status, as low levels of vitamin B12 can interfere with the body's ability to use folate (Gibson 2005; WHO 2008).
Laboratory test information, including analysis methods and machines used to measure folate and vitamin B12 biomarkers, is available from the Downloads page.
Comparison to other folate and vitamin B12 biomarker data
This is the second time the ABS has collected information on serum folate and vitamin B12. Both were previously collected in the NHMS 2011–12 and the NATSIHMS 2012–13. For information on time series comparability, see Comparing biomedical collections over time.
Red cell folate (RCF) was measured in the NHMS 2011–12 and the NATSIHMS 2012–13, but not in 2022–24. The RCF assay used previously has been evaluated since that time and was considered by researchers to have overestimated folate status in the Australian population compared to other accepted methods of analysis (Hunt et al. 2020). Some of the factors that assist in interpreting RCF data were not collected in 2022–24, for example pregnancy and oral contraceptive use (Gibson 2005; WHO 2015b).
Serum folate and vitamin B12 data has been collected in other non-ABS surveys. However, caution must be taken when interpreting results due to the differences in scope, assay and the instrument used, and any thresholds applied in the final analysis.
Folate
Definition
Folate is a B group vitamin (B9) that the body uses to make DNA and other genetic material. It is essential for healthy growth and development, particularly for the foetus in the first 3 months of pregnancy (McNulty 2024; WHO 2015a). Folate cannot be made by the body and is found naturally in food, such as green leafy vegetables, fruits and grains. The term ‘folate’ can also be used to refer to folic acid, which is the synthetic form of folate added to food or used in dietary supplements (Gibson 2005).
Folate deficiency can lead to macrocytic anaemia. Macrocytic anaemia is a type of anaemia where the body produces red blood cells that are larger than normal. Symptoms include fatigue, irritability, weakness, and palpitations (Gibson 2005).
Recent intake of dietary folate can be determined by measuring serum folate in a blood sample. Serum folate levels are low in folate deficiency related anaemia. The World Health Organization (WHO) also recommends serum folate testing for folate status monitoring (WHO 2008, 2015a, 2015b). In Australia, the national monitoring of folate status program mandated the addition of folic acid to all non-organic bread making wheat flour in 2009. Biomedical measurements of folate status forms part of this monitoring program (AIHW 2011a, 2011b, 2016).
As folate is known to play an important role in pregnancy, folic acid supplementation before conception and in early pregnancy is recommended worldwide and has been shown to protect against the occurrence of neural tube defects in babies, such as spina bifida (WHO 2015a).
There are two main measures of folate in the blood; recent folate intakes can be assessed by measuring serum folate levels, and long-term folate stores by measuring red blood cell folate levels (WHO 2008, 2015b).
The measurement of RCF, also known as erythrocyte folate, is a good indicator of longer-term folate stores in the body. In women of childbearing age, there is clear evidence associated with specific levels of RCF in the blood and protection against neural tube defects, such as spina bifida in a developing foetus (Gibson 2005; WHO 2015a).
The measurement of RCF is less sensitive than serum folate to dietary folate intakes. This is due to the life span (120 days) of the red blood cell and other factors that affect the levels of RCF in the body including age, pregnancy, smoking, oral contraceptive use and vitamin B12 deficiency (WHO 2015a, 2015b).
The 2013 National Health and Medical Research Council (NHMRC) Nutrient Reference Values for Australia and New Zealand includes dietary intake requirements for folate, expressed as dietary folate equivalents (NHMRC 2013a).
Methodology
Serum folate results were obtained for persons aged 12 years and over who provided a blood sample. Fasting was not required for this test.
Serum folate levels were measured at the Douglass Hanly Moir Pathology (DHM) laboratory by the competitive electro-chemiluminescence binding assay method (RCPA 2023a). The serum folate test measures the amount of folate circulating in the blood at the time of the test, expressed as nmol/L.
The reporting level for individuals for a serum folate value in the normal range from the laboratory test used was >7 nmol/L.
In 2012, WHO recommended that folate deficiency should be defined as serum folate concentrations of <10 nmol/L in population-based studies, which was supported in a 2015 update on folate. This value is based on the point at which homocysteine concentrations begin to increase (WHO, 2015a, 2015b). High levels of circulating homocysteine are considered a functional indicator of folate deficiency and results from the inability of folate to donate the methyl group necessary to convert homocysteine to methionine (WHO 2015b).
Interpretation
Points to be considered when interpreting data for this topic include the following:
- Serum folate results do not confirm a specific diagnosis of deficiency without consultation with a health professional.
- There are several different test methods to measure serum folate levels and each test method may produce different results. The data from this topic should therefore be used with caution when comparing serum folate results from other studies using a different test method.
Vitamin B12
Definition
Vitamin B12 is required for the synthesis of fatty acids in myelin and, in conjunction with folate, in DNA synthesis, red blood cell formation, brain function and when breaking down fatty and amino acids (NHMRC 2013b).
Adequate intake of vitamin B12 is essential for normal blood and neurological function. If left untreated, vitamin B12 deficiency can lead to anaemia, as well as nerve and brain damage. Vitamin B12 deficient anaemia has the same symptoms as folate deficient anaemia, as a result it cannot be diagnosed without a biomarker test (NHMRC 2013b).
Vitamin B12 is found in the fat of foods derived from animal products and deficiency may occur in people who avoid consuming these foods. Vitamin B12 deficiency may also occur due to malabsorption of the vitamin, more likely found in the elderly due to physiological changes associated with ageing.
The 2013 NHMRC Nutrient Reference Values for Australia and New Zealand includes dietary intake requirements for vitamin B12 (NHMRC 2013b). Inadequate intake of folate and vitamin B12 leads to low serum or plasma concentrations of both vitamins, and elevated plasma homocysteine. Low levels of vitamin B12 can indicate a deficiency, however further tests need to be conducted to determine the level of deficiency.
Methodology
Vitamin B12 results were obtained for persons aged 12 years and over who provided a blood sample. Fasting was not required for this test.
Vitamin B12 levels were measured at the DHM laboratory by the competitive electro-chemiluminescence immunoassay (ECLIA) method (RCPA, 2023b). The vitamin B12 test measures the amount of vitamin B12 circulating in the blood at the time of the test, expressed as pmol/L.
There is no consensus on the epidemiological cut-off reference values for measuring serum vitamin B12 in the blood, as it depends on the assay used.
The reporting level for individuals for a serum vitamin B12 value in the normal range from the laboratory test used was >145 pmol/L.
A WHO consultation in 2008 proposed a vitamin B12 cut-off for deficiency of <150 pmol/L (plasma) for population studies (WHO 2008). This reporting level has also been referenced elsewhere and can be applied to serum or plasma vitamin B12 measurements (NIH 2024).
Interpretation
Points to be considered when interpreting data for this topic include the following:
- Vitamin B12 results do not confirm a specific diagnosis of deficiency without consultation with a health professional.
- There are several different test methods to measure vitamin B12 levels and each test method may produce different results. The data from this topic should therefore be used with caution when comparing vitamin B12 results from other studies using a different test method.
- Biomedical monitoring data on vitamin B12 status assists the monitoring of folate status program, as high folate intakes (>1000 µg/day) may mask B12 anaemia and delay the correct diagnosis of vitamin B12 deficiency in older people (WHO 2008).
References
Australian Institute of Health and Welfare (AIHW) (2011a), Mandatory folic acid and iodine fortification in Australia and New Zealand: baseline report for monitoring, AIHW, Australian Government, accessed 20/02/2025.
Australian Institute of Health and Welfare (AIHW) (2011b), Mandatory folic acid and iodine fortification in Australia and New Zealand: supplement to the baseline report for monitoring, AIHW, Australian Government, accessed 20/02/2025.
Australian Institute of Health and Welfare (AIHW) (2016), Monitoring the health impacts of mandatory folic acid and iodine fortification 2016, AIHW, Australian Government, accessed 20/02/2025.
Gibson RS (2005), Assessment of folate and Vitamin B12 status, Principles of Nutritional Assessment, 2nd ed, Oxford University Press.
Hunt SE, Netting MJ, Sullivan TR, Best KP, Houghton LA, Makrides M, Muhlhausler BM, Green TJ (2020), Red Blood Cell Folate Likely Overestimated in Australian National Survey: Implications for Neural Tube Defect Risk, Nutrients, 12(5):1283, accessed 20/02/2025.
McNulty H (2024), ‘Folate’, Principles of nutritional assessment: 3rd Edition, Nutritional Assessment website, accessed 20/02/2025.
National Health and Medical Research Council (NHMRC) (2013b), ‘Vitamin B12’, Nutrient Reference Values for Australia and New Zealand, Eat For Health website, accessed 19/07/2023.
National Health and Medical Research Council (NHMRC) (2013a), ‘Folate’, Nutrient Reference Values for Australia and New Zealand, Eat For Health website, accessed 19/07/2023.
National Institutes of Health Office of Dietary Supplements (NIH) (2024), Vitamin B12, NIH website, accessed 20/02/2025.
Royal College of Pathologists of Australasia (RCPA) (2023a), ‘Folate’, RCPA Manual, RCPA website, accessed 19/07/2023.
Royal College of Pathologists of Australasia (RCPA) (2023b), ‘Vitamin B12’, RCPA Manual, RCPA website, accessed 19/07/2023.
World Health Organization (WHO) (2008), Conclusions of a WHO technical consultation on folate and vitamin B12 deficiencies, Food and Nutrition Bulletin, 29(2 Suppl.):S238-S244, accessed 20/02/2025.
World Health Organization (WHO) (2015a), Guideline: Optimal serum and red blood cell folate concentrations in women of reproductive age for prevention of neural tube defects, WHO, accessed 20/02/2025.
World Health Organization (WHO) (2015b), Serum and red blood cell folate concentrations for assessing folate status in populations, WHO, accessed 20/02/2025.