One of the bits of wisdom I've heard imparted to nursing moms from Lactation consultants and these sources are to drink a glass of alcohol (typically beer) to produce and maintain an adequate milk production.
However, a study from the Journal of Clinical Endocrinology and Metabolism (April 2005 publication) found that alcohol consumption did NOT increase milk production.
A summary of the study states:
Oxytocin levels for each woman fell a striking 78 percent during the session where she had the alcohol. The women also reported feeling more tired and less happy on those days. Prolactin levels, on the other hand, surged by 336 percent during the alcohol session. The two hormones that normally move together in the nursing dance, went spinning in opposite directions after a drink. The result? Women produced less milk (volume and calories). But high prolactin levels lead to an increased sensation of breast fullness, so mothers feel like they are making more milk even though they are making less. Babies suck more vigorously at the beginning of nursing after their mother has had a drink, leading many mothers to think that babies are drinking more. Probably they are sucking harder because they are getting less. Breastfed babies drink an average of 20 percent less milk after their mother has had alcohol.
A glass of alcohol does make mom sleepier and make her breasts feel fuller. This could be the explanation for the generations of folk wisdom. Because moms couldn't measure how much milk their babies were drinking, there was nothing to contradict this advice.
The word is still out on non-alcoholic beer and brewer's yeast as many mothers have reported increased milk production after using these products.
I find it interesting that the study showed alcohol's effects to be contradictory: the breasts felt fuller leading mothers to think that more milk was being produced, while in truth the opposite was true.