乳児の固形食導入時期と３歳の肥満の関係を847人の子どもの研究でみた。固形食solid foods 開始時期を、４ヶ月未満、４〜５ヶ月、６ヶ月以上に分けて比べると、母乳栄養では開始時期と肥満の関連はなかったが、人工乳で育った子どもは４ヶ月未満で固形食を開始した場合は３歳時の肥満が６倍に増加していた。|
Starting solid foods earlier linked to obesity risk
By Genevra Pittman
NEW YORK | Mon Feb 7, 2011 3:33am EST
NEW YORK (Reuters Health) - Babies raised on formula who start eating solid foods before they are 4 months old may be more likely to become obese than those who start later, suggests a new study.
The findings support U.S. guidelines that say parents should wait until babies are between 4 and 6 months old to start feeding them solid foods, said Dr. Susanna Huh, one of the study's lead authors from Children's Hospital Boston.
"Adhering to those guidelines could reduce the risk of obesity in childhood," she told Reuters Health.
Previous studies have shown conflicting results on whether the age at which babies start eating solid foods is related to their chance of being obese a few years down the line. Especially among babies who are raised on formula, the transition to solid foods might mean a jump in the amount of calories they are consuming - before parents have learned how much energy their baby really needs.
In the current study, Huh and her colleagues tracked about 850 babies and their mothers over 3 years. When babies were 6 months old, researchers asked the moms whether they had breastfed - and if so, for how long - and when they started feeding their babies solid foods, such as cereal, fruit, and dairy products.
When kids were 3 years old, the researchers measured their height and weight to determine which kids were obese, defined as being in the highest 5 percent of their age and gender for body mass index (BMI), a measure of the relationship between weight and height.
For babies who were breastfed for at least four months, the age that they first received solid food - before 4 months, at 4 or 5 months, or 6 months or later - had no effect on whether they were obese at 3 years. Regardless of when they started eating solid foods, breastfed babies in the study had a one in 14 chance of being obese as preschoolers.
But the findings, published in the journal Pediatrics, were different among babies who were formula-fed from the beginning, or who stopped breastfeeding before they were 4 months old.
Those babies had a one in four chance of being obese at age 3 if they started eating solid foods before they were 4 months old. If parents waited until between 4 and 5 months, the kids' chances of being obese were one in 20.
The chance of being obese increased again if babies didn't start eating solid foods until they were at least 6 months old, but there were too few of those babies for the authors to make a firm conclusion about the risk of waiting longer to feed a baby solid foods.
Both in the U.S. and around the world, doctors have been promoting the importance of breastfeeding in the first 4 to 6 months of life. However, in the U.S. about half of babies are breastfed for less than 4 months, or not breastfed at all, according to the Centers for Disease Control and Prevention.
Breastfeeding itself cuts down on a baby's risk of being obese. For those babies who are raised on formula, it seems to be especially important that parents wait until babies are at least four months old to feed them solid foods, researchers say.
While parents may have more difficulty determining the right amount to feed a baby who isn't breastfeeding, it could also be that "the way that infants feed and learn to feed influences their obesity risk," Huh said.
Dr. David McCormick, a pediatrician at The University of Texas Medical Branch at Galveston, said that the most common problem he sees is parents adding cereal to formula without thinking about the extra calories they are feeding their baby.
"I think that's what a lot of people are doing unknowingly, thinking that the baby will be healthier or grow faster," McCormick, who was not involved in the current study, told Reuters Health.
"That's exactly how (adults) get overweight," he said. "They eat a little bit more than they should every day."
The study shows that talking to parents about when to add solid foods to a baby's diet is something that pediatricians should be doing on a regular basis, McCormick said. Giving solid foods too early, whether together with formula or separately, "is going to set your child up for obesity."
And, he said, "We know from other (studies) that if you're overweight or obese at 3, you're very likely to stay overweight."
SOURCE: bit.ly/5N5tuZ Pediatrics, online February 7, 2011.
Published online February 7, 2011
Timing of Solid Food Introduction and Risk of Obesity in Preschool-Aged Children
Susanna Y. Huh, MD, MPHa, Sheryl L. Rifas-Shiman, MPHb, Elsie M. Taveras, MD, MPHb,c, Emily Oken, MD, MPHb, Matthew W. Gillman, MD, SMb,d
aDivision of Gastroenterology and Nutrition and
cDivision of General Pediatrics, Children's Hospital Boston, Boston, Massachusetts;
bObesity Prevention Program, Department of Population Medicine, Harvard Medical School/Harvard Pilgrim Health Care Institute, Boston, Massachusetts; and
dDepartment of Nutrition, Harvard School of Public Health, Boston, Massachusetts
Objective To examine the association between timing of introduction of solid foods during infancy and obesity at 3 years of age.
Methods We studied 847 children in Project Viva, a prospective pre-birth cohort study. The primary outcome was obesity at 3 years of age (BMI for age and gender ?95th percentile). The primary exposure was the timing of introduction of solid foods, categorized as <4, 4 to 5, and ?6 months. We ran separate logistic regression models for infants who were breastfed for at least 4 months ("breastfed") and infants who were never breastfed or stopped breastfeeding before the age of four months ("formula-fed"), adjusting for child and maternal characteristics, which included change in weight-for-age z score from 0 to 4 months--a marker of early infant growth.
Results In the first 4 months of life, 568 infants (67%) were breastfed and 279 (32%) were formula-fed. At age 3 years, 75 children (9%) were obese. Among breastfed infants, the timing of solid food introduction was not associated with odds of obesity (odds ratio: 1.1 [95% confidence interval: 0.3--4.4]). Among formula-fed infants, introduction of solid foods before 4 months was associated with a sixfold increase in odds of obesity at age 3 years; the association was not explained by rapid early growth (odds ratio after adjustment: 6.3 [95% confidence interval: 2.3--6.9]).
Conclusions Among formula-fed infants or infants weaned before the age of 4 months, introduction of solid foods before the age of 4 months was associated with increased odds of obesity at age 3 years.
Key Words: obesity . infant feeding . complementary foods
Abbreviations: OR = odds ratio . CI = confidence interval
Accepted Nov 19, 2010.
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