The potential renal acid load of infant formula milk products available in China

Breastfeeding is associated with enhanced renal growth and improved kidney function in infants. Formula-fed infants do not experience these benefits. A closer look at the nutritional composition of infant formula (IF) products in comparison to human breast milk (HBM) is thus warranted, particularly with regard to the potential renal acid load (PRAL_R) - an acknowledged risk factor for acid stress-induced kidney disease. We reviewed the PRAL_R of 783 IF products for infants aged 0-6 months and 786 IF products for children aged 6 to 12 months from China (2017-2024). In an additional exploratory analysis, data for IF products for infants aged 0-6 months were contrasted to HBM. The median PRAL_R of 783 IF products for infants aged 0-6 months was -0.97 (IQR: 1.76) mEq/100 g of IF powder; PRAL_R varied widely and ranged from -5.62 mEq/100 g (alkaline) to +1.80 mEq/100 g (acidic). A typical daily consumption of 800 ml of IF milk resulted in a slightly alkalizing potential (median PRAL_R: -0.97 (IQR: 1.76)), whereas the same amount of HBM exerted stronger alkalizing effects (PRAL_R: -3.06 mEq). Protein and phosphate content differences may explain these findings. Infant formulas for children aged 6 to 12 months exerted stronger acidifying effects. This is the first study to quantify the PRAL_R of IF products available in China. Results suggests that HBM and IF products exert a different acid load to the human kidneys. This could be relevant for the postprandial metabolic response of breast-fed and formula-fed infants and warrants consideration in future studies.