If you mean mixing breast milk and formula in one bottle or serving, then the answer is no. “By mixing the formula with breast milk, you alter the tonicity of the formula which might bring about diarrhea,” warns Dr. Cua-Lobo. Tonicity is the ability of a solution to cause a cell within it to gain or lose water.
However, if you want to supplement or alternate breast milk feeding with formula milk feeding, then go ahead.
“There is no correct mix or ‘formula',’” says Dr. Cua-Lobo.
“Priority is still breast milk for the child as it contains essential nutrients for the baby’s growth. Plus, breastfeeding provides that special bonding between mother and child.” When should a mother supplement? It depends on various factors. It's best for a mom to seek the advice of her pediatrician or health care provider.
Elena Cua-Lobo, M.D., M.P.H., pediatric pulmonologist, Sta. Cruz, Manila