Background: Cow's milk is a core ingredient in foods for prevention and treatment of undernutrition in children. It promotes growth, but there is limited knowledge of which components in milk have growth-stimulating effects.

Objective: To discuss the growth-stimulating effects of milk in undernourished children with emphasis on protein, lactose, and minerals.

Methods: We reviewed literature on dairy and growth in undernourished children.

Results: Cow's milk has a specific stimulating effect on linear growth, even in well-nourished children, and it may stimulate weight gain and muscle accretion in wasted children. Dairy protein has high protein quality scores with no major differences between whey protein concentrate and dried skimmed milk. Lactose has potential growth-stimulating effects, and the high content of potassium, phosphorus, magnesium, and zinc in milk is also likely to stimulate growth. Furthermore, a high dairy content reduces the amount of antinutrients from plant protein.

Conclusions: Dairy protein, lactose, and bioavailable minerals all have potential growth-stimulating effects, which make cow's milk an important ingredient in foods for undernourished children. Different dairy ingredients vary with regard to protein amount and quality, content of lactose, and minerals, and thereby growth stimulating effects. This should be taken into consideration when deciding which dairy ingredient to use. Challenges include the relatively high cost of dairy. Therefore, future studies should include cost-effectiveness analysis and assessment of the desirable content of each growth-promoting milk component.