MILWAUKEE – Babies may like to hit the bottle, but doctors warn that if they are more than 12 months old, they should stop suckling and start sipping.
Bottle-feeding is associated with iron deficiency and iron-deficiency anemia, according to research in this month’s Archives of Pediatric and Adolescent Medicine. And Mexican-Americans appear to be most at risk.
The study was conducted by researchers at the Medical College of Wisconsin and the Rochester School of Dentistry.
“This is a very interesting observation,” said Betsy Lozoff, a researcher in the department of pediatrics and communicable diseases at the University of Michigan who was not involved in the research. “And it’s very straightforward.”
The problem, said Jane Brotanek, assistant professor of pediatrics at the Medical College, – and lead author on the paper – is that when children drink milk from a bottle, they drink a lot of it. As a result, they forgo foods rich in iron.
In addition, large quantities of milk can cause irritation and bleeding in the gut.
Brotanek became interested in iron deficiency anemia many years ago. Working with Latino families, she noticed two things: Children tended to bottle-feed well beyond the age of 1, and they seemed to have a lot of iron deficiency and anemia.
Brotanek said that it is “culturally ingrained to give the bottle” in this community.
She said those mothers think “it is a good thing, that it helps to nurture and pacify” young children.
She wondered if there might be a connection between her two observations.
She searched a public database, called NHANES III, which is a large national survey conducted by the National Center for Health Statistics between 1988 and 1994. The database included surveys from 33,994 people.
Brotanek and her colleagues focused their investigation on three major racial/ethnic groups: blacks, whites and Mexican-Americans.
They found that among the 2,121 children represented in the sample – those between the ages of 1 and 3 – nearly one in every 10 had iron deficiency. The breakdown: 5.4 percent in whites, 8.0 percent among blacks and 16.9 percent among Mexican-American children.
In addition, they noticed as the age of bottle-feeders increased, so too did the prevalence of iron deficiency.
They then focused on ethnic background and bottle feeding. While most children were bottle-fed for less than 23 months, 36.8 percent of Mexican-American children between the ages of 2 and 4 were still drinking from a bottle.
Further investigation showed Mexican-American children were three times more likely to be iron deficient than white children between 24 and 48 months old. Children who were bottle-fed between the ages of 2 and 4 were three times more likely to be iron-deficient than those who stopped at the age of 1.
This led the researchers to conclude that prolonged bottle feeding and Mexican-American ethnicity are both associated with iron deficiency.
How tightly these two factors coincide remains a question. The authors pointed to an earlier study that showed Mexican ethnicity remained statistically associated with iron deficiency, even after there was a statistical adjustment for prolonged bottle-feeding.
The worry, said Brotanek, is that iron is critical for healthy development.
Iron-deficiency anemia has been associated with behavioral and cognitive delays, including impaired learning, decreased school achievement and lower scores on tests of mental and motor development, said Brotanek.
And while young babies are largely buffered from iron loss – they receive large iron stores from their mother at birth – it’s the older children who suffer, if not adequately fortified.
Therefore, pediatricians and others are starting to wonder whether iron supplements should be given to young children, and whether testing for iron in the blood should become routine, recommendations that some say are controversial.
Currently, no organization recommends universal blood testing for iron anemia in children between the ages of 1 and 3, said Frank Greer, professor of pediatrics at the University of Wisconsin-Madison. “But many feel they should.”
Brotanek said her study should signal pediatricians to ask parents about their child’s bottle-feeding practices. And they should educate parents about the need to wean their babies from bottles.
“It’s important for parents to get their child to transition to a cup as early as 9 months of age so they get used to the cup and are completely weaned from the bottle” by the time they hit age 1, said Brotanek.
She said children should not drink more than two 8-ounce cups of milk per day.
“We don’t want them to get too much,” she said. “It reduces their appetite for iron-rich food.”
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