维生素 A、D 都属于脂溶性维生素。维生素 A的主要来源为肝、鱼肝油、蛋黄、全脂乳,绿叶蔬菜和水果等,以鱼肝油含量最多。维生素 D 的主要来源为鱼肝油、猪肝、蛋黄、海鱼等。人皮肤中含维生素 D 前质,即7-脱氢胆固醇,经紫外线照射后可转变为维生素 D_3。植物中含麦角固醇,经日光中紫外线照射后转变为维生素 D_2,所以来源也较丰富。因此,一般合理地喂养婴儿,可以满足婴儿对 Vitamin A, D are fat-soluble vitamins. The main sources of vitamin A liver, cod liver oil, egg yolk, whole milk, green leafy vegetables and fruits, with the most content of cod-liver oil. The main source of vitamin D is cod liver oil, liver, egg yolk, marine fish and so on. Human skin contains vitamin D precursors, namely 7-dehydrocholesterol, after UV irradiation can be converted to vitamin D_3. Plant contains ergosterol, after UV irradiation into vitamin D_2, so the source is also more abundant. Therefore, it is generally reasonable to feed the baby to meet the baby