Why do we recommend cow's milk after 12 months? what about other milks?

What the evidence says

Before your baby turns one, their gut and kidneys aren't ready for cow's milk. The proteins and minerals in cow's milk are harder for a young baby's kidneys to handle, and cow's milk can irritate the lining of the stomach and intestines, sometimes causing tiny amounts of blood loss. It also doesn't have enough iron or vitamin C, or the right kind of fat, for a baby's fast brain growth. That combination raises the risk of iron deficiency anemia, which can affect development.

By 9 to 12 months, once your baby is eating a range of iron-rich solid foods, whole cow's milk becomes an appropriate part of their diet. Canadian guidelines recommend homogenized (3.25%) whole milk rather than skim or lower-fat versions, and suggest capping it at about 3 cups (750 mL) a day so there's still room for other foods.

What about plant-based milks, like almond, oat, rice or soy beverages? Canadian dietitians and paediatricians warn against using these as a child's main drink before age 2. These drinks are often very low in protein, fat and calories compared to cow's milk, and there have been reports of malnourished infants, and even one death, after being fed plant drinks as a main beverage. A recent review of the research found children who drank plant milk tended to have lower height, lower BMI, and lower blood levels of some nutrients compared to children drinking cow's milk.

Soy is a partial exception. Fortified soy infant formula is an accepted substitute for cow's milk-based formula in the first two years, for babies who can't have dairy for medical, cultural or religious reasons. But a fortified soy beverage (the kind sold as a drink, not formula) should still wait until age 2, same as other plant milks.

If your child can't or shouldn't have cow's milk before age 2, talk to your doctor or a dietitian about using breast milk, regular infant formula, or soy infant formula instead, rather than switching straight to a plant-based drink.