Methyl folate is inactive in purine and thymine biosynthesis and one of the main functions of vitamin B12 is the transfer of methyl groups from methyl folate for the synthesis of choline.

• 甲基叶酸盐在嘌呤和胸腺嘧啶生物合成中是无活性的，而B12的主要功能之一是从甲基叶酸盐传递甲基组提供胆碱合成。