Breast feeding provides optimal nutrition for proportionate infant growth, while formula fed infants have increased risks of becoming overweight or obese during childhood and adolescence, as well as being more susceptible to type two diabetes in later life.
This is attributed to increased protein concentrations in infant formula, as EU regulation states protein concentration cannot fall lower than 1.8g/100 kcal. Increased minimum protein content in formula is to counteract risk of inadequacy in essential amino acid quantities. In comparison, breast milk contains1.5g protein /100kcal.
Infant formula composition has continuously changed over the years in an attempt to resemble that of breast milk, the gold standard. Hence, the whey to casein ratio in infant formulas has been adjusted from 20/80 in bovine milk to 60/40 in infant formulas. But alpha-lactalbumin (a-lac), the major whey protein in breast milk accounting for approximately 25% of the total protein content (2.5–3.0 g/L), or about 36% of the whey protein, is still low in standard infant formulas due to its lower concentration in bovine milk, i.e., 3.5% of total protein, or 17% of the whey protein.
However, the authors of the current study, published in 'Nutrients', suggest that since α-lac in human and bovine milk exhibits a similar and favourable amino acid composition with abundant essential amino acids, especially tryptophan and cysteine, increasing its concentration in infant formula could enable further reduction of protein concentration with a protein composition and amino acid profile more similar to that of breast milk.
There are several existing clinical studies that suggest infant formula enriched with α-lac supports growth in-line with age expectancy, energy efficiency and gastrointestinal resilience.
Casein glycomacropeptide (CGMP) is a cleavage-product of bovine ĸ-casein, which contributes to an unfavourable amino acid profile with lack of essential aromatic amino acids such as tryptophan, phenylalanine, tyrosine and also cysteine, but is instead rich in threonine, proline, glutamine and serine.
The authors hypothesise the addition of CGMP-reduced whey could thus allow a reduction of total protein content, still providing adequate concentrations of essential amino acids.
The objective of the current study therefore was to evaluate the effect on growth of infants between two and six months of age fed protein-reduced infant formula, either enriched in α-lac or reduced in CGMP.
The randomised, double-blind trial, funded by Arla Foods Ingredients, explored a comparison in low protein formulas with α-lac enriched or CGMP - reduced whey, concluding that these formulas support adequate growth, with infants gaining more similar weight gain and metabolic profiles closer to that of BF infants.
The authors conclude: "Low-protein formulas enriched with α-lac-enriched or CGMP-reduced whey supports adequate growth, with more similar weight gain in α-lac-enriched formula group and BF, and with metabolic profiles closer to that of BF infants."
The study compared three groups of healthy term formula fed (FF) infants (n=328) and one reference group of healthy term BF infants (n=83) over six months. The first formula group were fed standard infant formula (SF) containing total protein content of 2.20g/100 kcal (10% α-lac); the second group were fed formula containing 1.75 g protein/100 kcal (27% α-lac); the third were fed formula with 1.76 g/100 kcal protein (14% α-lac) and a reduced level of CGMP (CGMP-RW). Study formulas included Lacprodan ALPHA-10, Lacprodan DI-8090 and Lacprodan DI-8095 and were provided by Arla Foods Ingredients.
Weight and length gain and head circumference in relation to consumed formula was recorded, and parents were asked to complete a detailed three-day dietary diary before each monthly visit. Stool frequency and consistency were registered daily as well as the occurrence of vomiting, stomach pain, flatulence, any illness, or medication. Blood samples were collected at baseline and at four and six months of age.
The resulting data revealed that weight gain as well as length gain per 100 kcal of consumed infant formula was similar in all formula groups between two and four months, four and six months and between two and six months, but length gain per 100 kcal tended to be higher in α-lac-EW than in SF infants at two to four months and two to three months (0.18 ± 0.05 vs. 0.16 ± 0.05, p = 0.07, PP population).
Weight gain and length gain per g protein intake, were higher in α-lac-EW and CGMP-RW, than in SF infants at the same time points.
Looking at the biochemical analysis, total branch chain amino acids (BCAA) were higher at four and six months in FF than in BF infants, but lower in α-lac-EW and CGMP-RW than in SF infants.
The study authors conclude: “Feeding infants low protein infant formula enriched with either high concentration of α-lactalbumin-enriched whey or CGMP-reduced whey is safe and well tolerated, providing adequate growth and a metabolic profile closer to that of BF infants.”
The report conclusions suggest an opportunity for comparable nutrition in FF and BF infants, however it adds that “overall growth was still slightly higher among infants fed the low-protein infant formulas compared to BF infants as were serum concentrations of BCAAs, IGF-1, insulin, and C-peptide.”
The study concludes that concentration of protein could be reduced further in formulas, with the requirement that quality of protein is kept high, but that long-term data on growth and metabolic profiles are needed for assessing the potential of long-term beneficial effects.
“Low-Protein Formulas with Alpha-Lactalbumin-Enriched or Glycomacropeptide-Reduced Whey: Effects on Growth, Nutrient Intake and Protein Metabolism during Early Infancy: A Randomized, Double-Blinded Controlled Trial”
Authors: Ulrika Tinghäll Nilsson, Olle Hernell, Bo Lönnerdal, Merete Lindberg Hartvigsen, Lotte Neergaard Jacobsen, Anne Staudt Kvistgaard and Pia Karlsland Åkeson.