When I donated to a milk bank in 2006, I don't remember giving a lot of information about my diet. They did ask if I was on any medications or taking supplements. I also had to have blood tests done to test for HIV and hepatitis. I'm not sure if the diet questions have changed in the past few years.
I have seen a FB page where woman post if they have extra milk and offer it up free of charge. There was info on diet and how it was stored, which would be important if you were taking from a non milk bank donor. You might poke around looking for that. When I had a lot of extra milk, I didn't know anyone who needed it, so I contacted the milk bank.
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