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Folate status as measured by serum or plasma folate
This indicator describes the use of serum and plasma folate as indicators of short-term folate status (1).
Individuals who consume foods fortified with folic acid may improve their folate status as noted by serum or plasma folate (2, 3), helping them avoid the negative consequences of folate deficiency. Adequate folate status in women of childbearing age protects against neural tube defects in pregnancy and other negative reproductive health outcomes (4). Serum and plasma folate are indicators of recent folate intake.
The folate status of the target population, as measured by plasma folate concentration
Serum or plasma folate concentrations can be presented as the average concentration in the population or by using a cut-off value to determine the percentage of the population with deficiency.
Average folate concentration
Numerator: the sum of serum or plasma folate concentrations for each individual assessed
Denominator: the number of persons assessed
• Divide the numerator by the denominator to obtain the average.
Percentage of the population with folate deficiency
Numerator: the number of individuals classified as having folate deficiency
Denominator: the number of persons assessed
• Divide the numerator by the denominator. Multiply the result by 100 to convert the number into a percentage.
Considerations for the calculations:
• There are two cut-off values for deficiency to consider. Using homocysteine concentrations as a metabolic indicator, the cut-off value for determining folate deficiency in all age groups is defined as serum or plasma folate lower than 4 ng/mL (10 nmol/L) (1). Using macrocytic anaemia as a haematological indicator, deficiency is defined as serum or plasma folate lower than 3 ng/mL (6.8 nmol/L) in all age groups (1).
assessment, folate deficiency, folate status, folic acid, micronutrient status, nutritional status, plasma, serum
All
Outcome
Improved nutritional status
School age children, 12-23 months, 24-35 months, 36-47 months, 48-59 months, 6-11 months, Adolescents, All, Men, Women of reproductive age
None,
Folate
Community, Health systems, Market-based
The collection of biological markers of micronutrient status, such as serum or plasma folate, requires laboratory expertise.
Serum or plasma folate is useful to understand recent folate intake in the population.
Serum or plasma folate may be expensive to analyse, depending on the method used, which might limit the ability to use this indicator. The collection and analysis of biological indicators of micronutrient status requires laboratory expertise to collect, process, store, and analyse, which might be a limitation for the use of these indicators in some contexts. Serum or plasma folate does not reflect folate stores.
Eighty non-pregnant and non-lactating women of reproductive age were randomly selected to participate in a cross-sectional survey where serum folate was measured. The survey results showed that three women had serum folate levels <4 ng/mL, indicating deficiency.
Numerator (serum folate <4 ng/mL) : 3
Denominator: 80
Calculation: 3/80 * 100 = 3.8% of the women selected had folate deficiency.
1. Serum and red blood cell folate concentrations for assessing folate status in populations. Vitamin and Mineral Nutrition Information System. Updated 2015. Geneva: World Health Organization; 2015 (WHO/NMH/NHD/EPG/15.01; http://apps.who.int/iris/bitstream/10665/162114/1/WHO_NMH_NHD_EPG_15.01.pdf, accessed 6 October 2015).
2. Abdollahi Z, Elmadfa I, Djazayery A, Golalipour MJ, Sadighi J, Salehi F et al. Efficacy of flour fortification with folic acid in women of childbearing age in Iran. Ann Nutr Metab 2011;58:188–96. doi:10.1159/000329726.
3. Pfeiffer CM, Caudill SP, Gunter EW, Osterloh J, Sampson EJ. Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999–2000. Ann J Clin Nutr. 2005;82:442–50.3. Pfeiffer CM, Caudill SP, Gunter EW, Osterloh J, Sampson EJ. Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999–2000. Am J Clin Nutr. 2005;82:442–50.
4. De-Regil LM, Fernandez-Gaxiola AC, Dowswell T, Pena-Rosas JP. Effects and safety of periconceptional folate supplementation for preventing birth defects. Cochrane Database Syst Rev. 2010(10):CD007950. doi:10.1002/14651858.CD007950.pub2.