Are there any restrictions on the consumption of human milk? Obviously, babies drink it but is it otherwise kosher for consumption?

Shulchan Aruch Yoreh Deah 81:7 writes: Woman’s milk is permitted as long as it is drunk from a Keli (cup, bowl etc.)…but an adult who breast feeds is receives a Makat Mardut….an adult in this matter is older than 4 years of age. For further explanation you should refer to the source. Rabbi Ro’i Margalit