Introduction to complementary foods for six-month-old babies Six months is when the baby starts to be exposed to complementary foods. In addition to breast milk/formula, some new foods are gradually introduced, such as vegetable purees, fruit purees, etc. These foods need to be carefully selected and prepared to ensure your baby is nourished and adapted to the new diet. The Correct Order of Puree When first introducing purée, choose a single vegetable, such as carrots or pumpkin. vegetables first