LeanMR as all our protein powders are safe during breast feeding as long as the mother doesn’t have a dairy allergy. If she does, then like anyone else, she would avoid dairy proteins and could use our Best Plant Protein. That said, the protein in LeanMR is whey isolate and therefore generally would not trigger an allergic reaction because most all dairy components are removed in creating the isolate amino acids.
I’m not sure what you mean “her daughter is allergic to milk” if she is breast feeding her daughter? Unless she’s only allergic to bovine milk and not human, which would be unusual. If so then have the mom use our Vegan (Best Plant Protein) protein.
Supplements that are ok during pregnancy or breastfeeding: the dotFIT multivitamin and mineral formula (Women’sMV during breastfeeding but use the doctor prescribed prenatal during pregnancy), SuperOmega-3s, any of the meal replacements and if needed, SuperCalcium and extra iron by doctors recommendation. If she needs a pre/post workout recovery drink or protein supplement, use one of our meal replacements/protein shakes such as Pre/Post Workout and Meal Replacement formula, WheySmooth (all natural if desired) or Best Plant Protein.