Anti-regurgitation infant formulas and antacid medication: match or mismatch?

A perceived need for treatment has led to the development and widespread marketing of various anti-regurgitation (AR) infant formulas, promoted as effective solutions for managing regurgitation symptoms. For practice, limited comparative data exists on the specific thickening agents, or the relative thicknesses of AR formulas. An added concern is that some infants on AR formulas simultaneously receive pharmacological treatments for reflux, such as antacids or gastric acid inhibitors, and no information about compatibility is available. One reference formula (Nutrilon® Profutura 1, Nutricia) and four formulas labelled as 'anti-regurgitation' with different nutritional compositions were used to evaluate the effect of pH and time on viscosity. The viscosity of marketed AR formulas was tested with a rotational rheometer. All four AR formulas demonstrated higher viscosity compared to the reference formula, with notable differences based on the thickening strategy used by the manufacturer. Pre-thickened CBG-based AR formulas generally showed higher viscosity than pre-thickened starch-based formulas. Adding a casein-dominant protein fraction increased viscosity in acidic environments; however, this effect gradually diminished over time, likely due to protein hydrolysis. Moderate (pH 4) compared to strong acidic conditions (pH 1) had only minimal impact on viscosity, indicating compatibility with gastric acid inhibitors across all AR formulas.

Our findings suggest that CBG-based AR formulas should be allowed to stand for at least 30 min after preparation to achieve the intended viscosity. Additionally, AR formulas thickened with CBG generally exhibit higher viscosity than pre-thickened starch-based formulas. Notably, casein-based thickening occurs even when gastric acid suppressants are used, and combining casein with acid suppression may even slow down the rate of viscosity reduction over time.

• Commercially available infant formula sometimes uses thickening agents to reduce regurgitation, but their effectiveness may vary depending on composition and gastric conditions. • Some thickening agents require an acidic environment to activate, which may be compromised by concurrent use of gastric acid suppressants.

• This study demonstrates that CBG-based AR formulas generally maintain higher viscosity than starch-based formulas, even with acid suppression. • Viscosity in some formulas changes over time, indicating that preparation timing affects therapeutic consistency.