Latest revision as of 15:26, 5 April 2024
Information about message (contribute ) This message has no documentation.
If you know where or how this message is used, you can help other translators by adding documentation to this message.
Message definition (Folate ) 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 B<sub>12</sub> 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 B<sub>12</sub> 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.
ULを超える量の葉酸の長期摂取を求めた臨床試験のレビューでは、懸念が提起されている。サプリメント由来の過剰摂取は、天然食品由来の摂取よりも懸念され、ビタミンB12 との相対的な割合が、有害作用の重要な要因となる可能性がある。一説によると、葉酸を生物学的に活性な形に変換する酵素ジヒドロ葉酸還元酵素 の速度が制限されるため、大量の葉酸を摂取すると、血中に未代謝の葉酸が検出可能な量だけ循環するようになるという。血中の葉酸が健康に悪影響を及ぼすという証拠は一貫しておらず、葉酸には、遊離葉酸が疾患発症に関与する可能性を高めるような補因子機能は知られていない。しかし、ビタミンB12 の低値と葉酸の高摂取の組み合わせは、先に述べた神経障害のリスクに加えて、高齢者の認知機能障害のリスクを増加させるようである。1,000 μg/日を超える葉酸サプリメントの長期使用は、前立腺がんリスクの上昇に関連している。