Breast-feeding has long been associated with increased health benefits for babies and mothers, but a new study points out that even breast milk may have limitations, especially as the infant gets older.
Doctors have long advised breast-feeding women to take vitamin D supplements, since breast milk does not contain high amounts of the nutrient. Vitamin D can be crucial in helping the body absorb calcium, and children with extremely low levels of vitamin D could be at risk of developing rickets or a bowing of the bones.
The American Academy of Pediatrics recommends that children take vitamin D supplements for the first year of life, regardless of whether they're fed formula or breast milk.
But a new study finds that children who are both eating solid food and breast-feeding are at higher risk for vitamin D deficiency. Published today in the American Journal of Public Health, the study looked at 2,508 children in Toronto, Canada.
Researchers found that children who were breast-fed up to 36 months and did not take supplements were more likely to develop vitamin D deficiency even though they had started eating solid foods. Children who were breast-fed up to 24 months had an estimated 16 percent risk of low levels of vitamin D. That number increased to 29 percent when the child breast-fed up to 36 months.
Dr. Sarah Ronis, a pediatrician at University Hospitals Rainbow Babies and Children’s Hospital, said the study could help mothers make important decisions about their diet.
The takeaway from the study is that children who are breast-fed longer without vitamin D supplementation are unlikely to be getting "sufficient intake from other sources," she told ABC News.
Ronis pointed out that breast milk remains an optimal source of nutrition for newborns and that the World Health Organization advises breastfeeding for up to two years for infants as long as it works for both mother and child. However she explained that they advise all mothers to give infants vitamin D supplements until the child can drink at least 32 ounces of formula or regular milk to get enough vitamin D in their diet.
She pointed out that the study shows how even solid food may not be a sufficient source of vitamin D for breast-feeding children. A deficiency can lead to "fatigue or impaired immune function" in extreme cases, Ronis noted. Some cases have been so severe that the calcium metabolism is thrown off, leading to changes in the bone.
She reiterated that breast milk is still recommended, as long as there are no other complications. The American College of Obstetricians and Gynecologists recommends that mothers breast-feed exclusively for the first six months of life or longer.