This special form of vitamin D is naturally present in breastmilk.
这种特殊形式的维生素D天然存在于母乳中。
《柯林斯英汉双解大词典》
2
Macfarlane guessed that the fact that water had to be boiled, together with the stomach-purifying properties of tea meant that the breastmilk provided by mothers was healthier than it had ever been.