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Providing perspectives on recent research into vitamins and nutritionals


Using Nutrition Status Measurements to Guide Food Fortification & Supplementation

By Michael McBurney

Without doubt, food fortification improves nutrition and health outcomes. In Canada, mandatory fortification of white flour, enriched pasta, and cornmeal products with folic acid has reduced the incidence of neural tube defects (NTDs) by 46%. Folic acid fortification and recommendations to supplement have reduced the risk of NTDs in many countries. Of course, consumers have to choose these products because those who avoid enriched/fortified foods are much less likely to meet their RDA. This may explain why 22% of Canadian women of childbearing age still have red blood cell (RBC) folate concentrations below recommended levels to prevent NTDs.

Nutrient requirements, the Estimated Average Requirements (EAR) and Recommended Daily Allowances (RDA), are based upon population statistics and limited experimental data on human metabolism. Fortification levels in foods are derived from EARs and mathematical modeling of fortifying different food groups to predict the impact on dietary intake. It is a game of averages built upon a foundation of assumptions. In the end, outcomes such as risk (incidence of NTDs which takes at least the span of a pregnancy to measure) or nutrition status ae assessed.

Plumptre and colleagues measured the folic acid status in 368 pregnant Canadian women. The RDA for pregnant women is 600 µg/day. On average, the women were consuming only 483 and 465 µg/day from their diet during early and late pregnancy, respectively. Clearly, public health is successfully reaching this cohort of Canadian women since 90% reported using folic acid supplements (93% use during early pregnancy). Eighty-three percent reported using a daily supplement with ≥1 mg folic acid.  Not surprisingly, the women had serum RBC folate concentrations above levels recommended to reduce risk of NTDs (<305 nmol/L). Women who supplemented in late pregnancy had higher RBC folic concentrations at delivery although plasma homocysteine concentrations were similar. Maternal RBC folate concentrations were positively correlated with cord blood concentrations.

The RBC folate concentrations, and unmetabolized folic concentrations (UMFA), reported by Plumptre and colleagues are higher than those reported in countries where foods are not fortified. Part of the difference could be attributable to analytical methodology. Certain genotypes were also associated with lower folic acid concentrations, as discussed earlier this week.

By measuring nutritional status of individuals, dietary guidance can be altered to optimize blood concentrations. Biologically-based measures are a far more accurate means to guide nutrition policy on fortification and supplement use than self-reported dietary recall data.

The future is here. Rise up and ask for more routine use of objective measures of nutritional status.

Main Citation

Plumptre L, Mashih SP, Ly A, Aufreiter S, Sohn K-J, Croxford R, Lausman AY, Berger H, O’Connor DL, Kim Y-I. High concentrations of folate and unmetabolized folic acid in a cohort of pregnant Canadian women and umbilical cord blood. 2015 Am J Clin Nutr doi: 10.3945/ajcn.115.110783

Other Citations

Title 21: Food and Drugs. Chapter I: Food and Drug Administration, Department of Health and Human Services. Subchapter B: Food for human consumption. Part 101: Food labeling. Subpart E: Specific requirements for Health Claims. Section 101.70 Health Claims: Folate and neural tube defects.

Rosenthal J, Casas J, Taren D, Alverson CJ, Flores A, Frias J. Neural tube defects in Latin America and the impact of fortification: a literature review. 2014 Publ Health Nutr doi: 10.1017/S1368980013000256

Castillo-Lancellotti C, Tur JA, Uauy R. Impact of folic acid fortification of flour on neural tube defects: a systematic review. 2013 Publ Health Nutr doi: 10.1017/S1368980012003576

Fulgoni VL, Keast DR, Bailey RL, Johanna Dwyer. Foods, fortificants, and supplements: Where do Americans get their nutrients? 2011 J Nutr doi: 10.3945/jn.111.142257

Colapinto CK, O’Connor DL, Tremblay MS. Folate status of the population in the Canadian Health Measures Survey. 2011 CMAJ doi:10.1503/cmaj.100568