Efficacy and safety of vitamin B12 fortification

Authors: Allen, Lindsay - A

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/20/2017
Publication Date: 6/20/2018
Citation: Allen, L.H. 2018. Efficacy and safety of vitamin B12 fortification. Book Chapter. https://doi.org/10.1016/B978-0-12-802861-2.00026-2.
DOI: https://doi.org/10.1016/B978-0-12-802861-2.00026-2

Interpretive Summary: Vitamin B12 in the diet is found only in animal source foods and since low amounts of such foods are consumed by many population groups, the global prevalence of vitamin B12 deficiency and depletion could be higher than that of any other nutrient. At the population level low intakes tend to result in subclinical deficiency, detected by changes of B12 and metabolites in the blood, rather than clinical symptoms such as megaloblastic anemia and neurological problems. However there is substantial evidence that even marginal deficiency is associated with a range of adverse health outcomes such as neural tube defects, low amounts of the vitamin in breast milk and poor infant and child development, and reduced cognitive function in elderly. Assessment of the B12 status if a population or group of people usually relies on measurement of serum or plasma vitamin B12, although three additional markers can be helpful, and a newer method of combining two to four measures (combined B12, or cB12) is promising to be a better diagnostic tool. Vitamin B12 status is directly related to intake although a much lower percent of the dose consumed is absorbed from higher dietary intakes. There is no known health risk from consuming very high intakes. In 2008, in an international consensus meeting, the recommendation was to add the vitamin at 40 ug/kg flour assuming a population group consumed 75 to 100 g flour per day. Lower levels of fortification ae needed where more flour is consumed. A recent well-designed, well-monitored national flour fortification program that added B12 to flour in Cameroon showed substantial increases in plasma and breast milk B12 at the end of one year, and suggests that the recommended levels of addition are probably higher than necessary. There are many potential health benefits from vitamin B12 fortification for depleted population groups, including reducing concerns about the potential for high folic acid intake (e.g. from fortified flour and supplements) to exacerbate B12 deficiency. Recommendations are made for outcomes that should be monitored in future national vitamin B12 fortification programs.

Technical Abstract: Due to the low intake of animal source foods by many population groups, the global prevalence of vitamin B12 deficiency and depletion could be higher than that of any other nutrient. At the population level low intakes tend to result in subclinical deficiency rather than clinical symptoms such as megaloblastic anemia and neurological problems. However there is substantial evidence that even marginal deficiency is associated with a range of adverse health outcomes such as neural tube defects, low amounts of the vitamin in breast milk and poor infant and child development, and reduced cognitive function in elderly. Assessment of status at the population level usually relies on measurement of serum or plasma vitamin B12, although three additional markers can be helpful, and a newer method of combining two to four measures (combined B12, or cB12) is promising to be a better diagnostic tool. Vitamin B12 status is directly related to intake although the efficiency of absorption falls greatly above usual dietary intakes. There is no known health risk from consuming very high intakes. In 2008, in an international consensus meeting, the recommendation was to add the vitamin at 40 ug/kg flour assuming consumption of 75 to 100 g flour per day, with lower levels of addition where more flour is consumed. A recent well-designed, well-monitored national flour fortification program that included B12 in Cameroon showed substantial increases in plasma and breast milk B12 at the end of one year, and suggests that the recommended levels of addition are probably higher than necessary. There are many potential health benefits from vitamin B12 fortification of depleted population groups, including allaying concerns about the potential for high folic acid intake to exacerbate B12 deficiency. Recommendations are made for outcomes that should be monitored in future national vitamin B12 fortification programs.