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DRI Dietary Reference Intakes: For Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline
which there was also a lack of controlled, dose-response data, a UF of 5 is large. The selection of a relatively large UF is based primarily on the severity of the neurological complications observed but also on the use of a LOAEL rather than a NOAEL to derive the UL. The UF is not larger than 5 on the basis of the uncontrolled observation that millions of people have been exposed to self-treatment with about one-tenth of the LOAEL (i.e., 400 µg in vitamin pills) without reported harm.
Derivation of a UL. The LOAEL of 5 mg/day of folate was divided by a UF of 5 to obtain the UL for adults of 1 mg/day or 1,000 µg/ day of folate from supplements for fortified food. A UL of 1,000 µg/day is set for all adults rather than just for the elderly because of (1) the devastating and irreversible nature of the neurological consequences, (2) data suggesting that pernicious anemia may develop at a younger age in some racial or ethnic groups (Carmel and Johnson, 1978), and (3) uncertainty about the occurrence of vitamin B12 deficiency in younger age groups. In general, the prevalence of vitamin B12 deficiency in females in the childbearing years is very low and the consumption of supplemental folate at or above the UL in this subgroup is unlikely to produce adverse effects.
Folate UL Summary, Adults
UL for Adults
19 years and older
1,000 µg/day of folate from fortified food or supplements
Other Life Stage Groups
There are no data on other life stage groups that can be used to identify a NOAEL or LOAEL and derive a UL. For infants the UL was judged not determinable because of a lack of data on adverse effects in this age group and concern about the infant’s ability to handle excess amounts. To prevent high levels of intake, the only source of intake for infants should be from food. No data were found to suggest that other life stage groups have increased susceptibility to adverse effects of high supplemental folate intake. Therefore, the UL of 1,000 µg/day is also set for adult pregnant and lactating women. The UL of 1,000 µg/day for adults was adjusted for children and adolescents on the basis of relative body weight as described in Chapter 3. Values have been rounded down.