Too much milk leads to iron deficiencies

New research says that drinking too much cow’s milk each day is linked to iron deficiency in young children. Results also showed no benefit from the increased intake of vitamin D.

A Canadian study examined the association between vitamin D and iron stores with daily milk consumption in 1,366 healthy urban children aged 2 to 5 years. Data were collected during routine health visits. Milk intake by cup or bottle was measured by parents’ reports. Vitamin D and iron stores were calculated using serum 25-hydroxyvitamin D and ferritin.

Analysis showed that each 250 mL cup of cow’s milk consumed increased 25-hydroxyvitamin D by 6.5% and decreased serum ferritin by 3.6%. Children who drank more milk had lower serum ferritin. Among children fed milk from a bottle, milk consumption did not increase median 25-hydroxyvitamin D but dramatically decreased median serum ferritin, supporting previous findings that children using a bottle are at increased risk for iron deficiency.

Vitamin D and iron are essential nutrients for children’s health and development. Vitamin D promotes calcium absorption for bone health and the prevention of rickets and may also prevent chronic conditions such as respiratory, cardiovascular, and autoimmune diseases. Dietary iron aids early brain development, and iron deficiency with or without anemia permanently impairs psychomotor development.

The researchers found that 2 cups (500 mL) of cow’s milk a day appeared sufficient to maintain healthy vitamin D stores without affecting serum ferritin, consistent with recommendations from the American Academy of Pediatrics. However, children with darker skin pigmentation should be given vitamin D supplements during the winter months to maintain vitamin D stores.