Doctors may want to advise parents against giving their infants lactose-reduced infant formula unless absolutely necessary, because doing so may be setting babies up for an increased risk of obesity in toddlerhood, new research shows.
Infants who drink infant formula instead of breast milk already carry an increased risk of obesity. But the new study, published in The American Journal of Clinical Nutrition, found a difference in types of formula and obesity outcomes for children.
Babies under 1 year who received lactose-reduced formula made partially of corn syrup solids were at a 10% greater risk (risk ratio, 1.10; 95% confidence interval, 1.02, 1.20; P = .02) of being obese by age 2 than infants who received regular cow’s milk formula.
“This is even another reason to not use a low-lactose formula,” said Mark R. Corkins, MD, division chief of pediatric gastroenterology, hepatology, and nutrition at the University of Tennessee Health Science Center, Memphis, who was not involved in the study. “Parents think if babies are fussy, or they spit up, they have lactose intolerance, but if you look at the actual numbers, lactose intolerance in infants is rare.”
Actual lactose intolerance in infancy is the result of a newborn receiving the same mutated gene from both parents, called congenital lactase deficiency, said Dr. Corkins.
“The reason the low-lactose formulas are even on the market is because parents want them, and they think their kid is lactose intolerant, but they are not,” Dr. Corkins said.
Researchers from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in southern California and the University of Southern California, Los Angeles, analyzed data from over 15,000 infants in southern California enrolled in WIC.
Records from infants born between Sept. 2012 and March 2016 were separated into two groups: infants that had stopped breastfeeding by month 3 and had started reduced-lactose formula and infants who received all other forms of formula. Over 80% of infants in both groups were Hispanic.
Infants who received the reduced-lactose formula with corn syrup solids were at an 8% increased risk of obesity by age 3 (RR = 1.08; 95% CI, 1.02, 1.15; P = .01), compared with children who received regular cow’s milk formula, and a 7% increased risk by age 4 (RR = 1.07; 95% CI; 1.01, 1.14; P = .01).
Tara Williams, MD, pediatrician and breastfeeding specialist associated with the Florida Chapter of American Academy of Pediatrics, said the findings should make pediatricians, parents, and others pause and consider what infant formulas contain.
She explained that babies who receive formula have higher obesity risk than babies who are breastfed overall. But research into the effects of different types of formula is relatively new. She said there may be a few reasons for the association between reduced-lactose, corn syrup solid formula and a higher risk of obesity.
“The addition of the corn syrup really starts to potentially teach that child to like sweet things,” Dr. Williams said, which in turn can lead to less healthy eating habits in childhood and adulthood.
Or, it may be that parents who tend to give their children lactose-reduced formula are less likely to be tolerant of fussy babies and end up feeding their babies more, Dr. Williams hypothesized.
In addition, emerging research shows corn syrup may act differently from other sugars in the gut microbiome and as it is metabolized in the liver, leading to weight gain.
Although parents make individual choices for what kind of formula to feed their infants, states play a large role in these choices. In 2018, 45% of babies in the United States were eligible for WIC, which is funded through the federal government but administered by states. State WIC programs request bids from formula manufacturers, and products chosen are then redeemed at retailers by parents.
“Now that we’re starting to see a signal that perhaps some formulas will have a potentially added risk of obesity for participants, states may say that when we’re helping mothers select among the formulas, we need to be very explicit about this additional risk,” said Christopher Anderson, PhD, MSPH, associate research scientist at the southern California Public Health Foundation Enterprises WIC and lead author of the study.
Dr. Williams said more research to do similar analyses in other populations is needed to draw cause and effect conclusions, while Dr. Corkins said he’d like to see more research into the amount of formula eaten and health connections to types of formula.
“We know as soon as you sign up for a baby registry at Target, you’re getting formula samples in the mail. You’re very aggressively marketed to; it’s a $55 billion industry,” Dr. Williams said. “And their goal is to sell their product – not to promote the health of infants. “This research certainly will cause us to pause and consider what we are feeding our infants in the United States and how we allow companies to market their products.”
Dr. Goran receives book royalties from Penguin Random House and is a scientific consultant for Yumi Foods and Else Nutrition. All other authors disclosed no conflicts of interest. Dr. Corkins reports working at a clinic that’s the site of a Takeda pharmaceutical research study. Dr. Williams reports no relevant financial relationships.