Weight Gain: Careful With Your Baby's Formula

Monell Center researchers found that the type of formula an infant is being fed, influences his/her weight gain, which means that parents need to be very careful, since the child can develop obesity, diabetes or other diseases later in life.

Most baby formulas are based on cow milk, but there are some soy-based and protein hydrolysate-based formulas.

Protein hydrolysate formulas contain pre-digested proteins and are usually fed to infants who cannot tolerate the intact proteins in other formulas.

Normally, in adults, pre-digested proteins act in the intestine to give the signal for the end of the meal, leading to smaller meals and limiting the calories intake.

Based on these observations, the researchers speculated that children being fed protein hydrolysate formulas would eat less and their growth patten would be affected, compared to infants eating cow's milk-based formula.

Study lead author Julie Mennella, PhD, a developmental psychobiologist at Monell said that “events early in life have long-term consequences on health and one of the most significant influences is early growth rate.

“We already know that formula-fed babies gain more weight than breast-fed babies.

“But we didn't know whether this was true for all types of formula.”

So researchers randomly assigned two-week-old infants, whose parents had already decided to bottle-feed, to a group being fed a cow's milk-based formula (35 infants) or to the protein hydrolysate formula group (24 infants), for the following seven months.

Both formulas had the same amount of calories, except that the hydrolysate formula had more protein, including larger amounts of small peptides and free amino acids.

The children were weighed once each month in the laboratory, where they also were videotaped consuming a meal of the assigned formula.

Once the infant signaled he/she was full, the meal stopped, and during the seven-month period, the researchers noted that the babies fed on protein hydrolysate gained weight slower than those being fed cow milk formula.

There were no differences in terms of linear growth, or length, between the two groups, so the only conclusion was that the only differences in growth were weight-related.

The scientists also compared the data to national norms for breast-fed babies, and found that the rate of weight gain of protein hydrolysate infants was comparable to the breast milk standards.

On the other hand, infants fed cow's milk formula gained weight at a higher rate than the same breast milk standards.

After analyzing the laboratory meals, the researchers saw that the infants fed the protein hydrolysate formula ate less.

Mennella said that “one of the reasons the protein hydrolysate infants had similar growth patterns to breast-fed infants, who are the gold standard, is that they consumed less formula during a feed as compared to infants fed cow's milk formula.

“The next question to ask is: Why do infants on cow's milk formula overfeed?

“All formulas are not alike,” she added, the proof being that “these two formulas have the same amount of calories, but differ considerably in terms of how they influence infant growth.”

This study highlights the necessity of understanding the long-term effects of infant formula composition on feeding behavior, growth, and metabolic health.

According to the researchers, future studies should use measures of energy metabolism and expenditure to look at how the individual formulas influence growth, and how each differs from breastfeeding.

This study was published online in the journal Pediatrics.