Folate/ja: Difference between revisions

The U.S. Institute of Medicine defines Estimated Average Requirements (EARs), Recommended Dietary Allowances (RDAs), Adequate Intakes (AIs), and Tolerable upper intake levels (ULs) – collectively referred to as [[Dietary Reference Intake]]s (DRIs). The [[European Food Safety Authority]] (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in United States. For women and men over age 18 the PRI is set at 330 μg/day. PRI for pregnancy is 600 μg/day, for lactation 500 μg/day. For children ages 1–17 years the PRIs increase with age from 120 to 270 μg/day. These values differ somewhat from the U.S. RDAs. The United Kingdom's Dietary Reference Value for folate, set by the Committee on Medical Aspects of Food and Nutrition Policy in 1991, is 200 μg/day for adults.

===Safety===

The risk of toxicity from folic acid is low because folate is a water-soluble vitamin and is regularly removed from the body through urine. One potential issue associated with high doses of folic acid is that it has a masking effect on the diagnosis of [[pernicious anaemia]] due to vitamin B₁₂ deficiency, and may even precipitate or exacerbate neuropathy in vitamin B12-deficient individuals. This evidence justified development of a UL for folate. In general, ULs are set for vitamins and minerals when evidence is sufficient. The adult UL of 1,000 μg for folate (and lower for children) refers specifically to folic acid used as a supplement, as no health risks have been associated with high intake of folate from food sources. The EFSA reviewed the safety question and agreed with United States that the UL be set at 1,000 μg. The Japan National Institute of Health and Nutrition set the adult UL at 1,300 or 1,400 μg depending on age.

Reviews of clinical trials that called for long-term consumption of folic acid in amounts exceeding the UL have raised concerns. Excessive amounts derived from supplements are more of a concern than that derived from natural food sources and the relative proportion to vitamin B₁₂ may be a significant factor in adverse effects. One theory is that consumption of large amounts of folic acid leads to detectable amounts of unmetabolized folic acid circulating in blood because the enzyme [[dihydrofolate reductase]] that converts folic acid to the biologically active forms is rate limiting. Evidence of a negative health effect of folic acid in blood is not consistent, and folic acid has no known cofactor function that would increase the likelihood of a causal role for free folic acid in disease development. However, low vitamin B₁₂ status in combination with high folic acid intake, in addition to the previously mentioned neuropathy risk, appeared to increase the risk of cognitive impairment in the elderly. Long-term use of folic acid dietary supplements in excess of 1,000 μg/day has been linked to an increase in prostate cancer risk.

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===Food labeling===

For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For folate labeling purposes 100% of the Daily Value was 400&nbsp;μg. As of the 27 May 2016 update, it was kept unchanged at 400&nbsp;μg. Compliance with the updated labeling regulations was required by 1 January 2020 for manufacturers with [[US$]]10&nbsp;million or more in annual food sales, and by 1 January 2021 for manufacturers with lower volume food sales. A table of the old and new adult daily values is provided at [[Reference Daily Intake]].

European Union regulations require that labels declare energy, protein, fat, saturated fat, carbohydrates, sugars, and salt. Voluntary nutrients may be shown if present in significant amounts. Instead of Daily Values, amounts are shown as percent of Reference Intakes (RIs). For folate, 100% RI was set at 200&nbsp;μg in 2011.