Milk

From Advice to a Wife [1880]:

Passion is injurious to the mother's milk, and consequently to the child. Sudden joy and grief frequently disorder the infant's bowels, producing griping, looseness, &c.; hence, a mother who has a mild, placid, even temper generally makes an excellent nurse, on which account it is a fortunate circumstance that she is frequently better-tempered during suckling than at any other period of her life; indeed, she usually, at such times, experiences great joy and gladness.

If the mother or the wet nurse be good-tempered, the milk will be more likely to be wholesome, which will of course make him more healthy, and consequently better tempered. While, on the other hand, if the mother or the nurse be of an irritable, cross temper, the milk will suffer, and will thus cause disarrangement to the system; and hence, ill-health and ill-temper will be likely to ensue.

Verdict:

Approved.