叶酸缺乏通常是由于维生素吸收不足引起的。孕期和哺乳期以及儿童生长发育过程中对叶酸的需求增加。由于吸收或代谢变化或药物的影响，摄入富含叶酸的食物无法保证所需的剂量，因此需要补充。
Deficiency of folic acid is usually caused by insufficient absorption of the vitamin. During pregnancy and lactation, the need for folic acid is increased during the growth of children. Under the influence of absorption or metabolic changes or drugs, the consumption of foods rich in folic acid cannot guarantee the dose provided, so it needs to be supplemented.
