LGG and Cow's Milk Protein Allergy in Infants

Cow's milk protein allergy is an immune reaction to proteins in cow's milk, and most infants outgrow it during early childhood. Trials from one Italian research group found that infants given an extensively hydrolysed formula containing Lactobacillus rhamnosus GG developed tolerance sooner. The evidence is promising but not yet confirmed widely enough to change standard care.

What is cow's milk protein allergy?

The allergy, abbreviated CMPA, occurs when the infant's immune system reacts to casein or whey proteins. It is different from lactose intolerance, which is difficulty digesting milk sugar and does not involve the immune system.

CMPA takes two broad forms. In the IgE-mediated form, symptoms such as hives, swelling or vomiting appear within minutes to two hours of exposure. In the non-IgE-mediated form, symptoms develop over hours to days and include eczema, reflux, mucus or blood in stools, colic-like crying and poor weight gain. Mixed presentations also occur.

The mainstay of management is removing cow's milk protein. Formula-fed infants switch to an extensively hydrolysed formula, in which proteins are broken into small fragments, or to an amino acid formula in more severe cases. Breastfeeding mothers may be advised to remove dairy from their own diet under supervision.

What did the LGG trials find?

A research group at the University of Naples Federico II, led by paediatric gastroenterologists studying food allergy, ran a series of studies beginning around 2012. Infants with CMPA were given one of several formulas, including an extensively hydrolysed casein formula with added LGG.

After 6 and 12 months, a larger proportion of infants receiving the LGG-containing formula passed an oral food challenge, the supervised test in which a child is given cow's milk to see whether symptoms recur. A later randomised trial from the same group reported fewer other allergic conditions, such as eczema, asthma and allergic rhinitis, over the following years in children who had received the LGG-supplemented formula.

These findings are notable, but several cautions apply:

• most studies come from a single research centre
• LGG was given within a specific hydrolysed casein formula, not as separate drops
• it is difficult to separate the effect of LGG from the effect of the formula itself
• independent replication in other populations is limited

How might LGG promote tolerance?

Oral tolerance is the immune system's learned ability to accept food proteins without reacting. It depends on regulatory T cells, immune cells that dampen unwanted responses, and on a healthy gut barrier.

Laboratory work from the Naples group and others suggests that LGG increases butyrate-producing bacteria in the infant gut. Butyrate, a short-chain fatty acid produced when bacteria ferment fibre, supports regulatory T cells and helps maintain the gut lining. Some studies also reported changes in DNA methylation, chemical tags that switch genes on or off, in immune genes of children who acquired tolerance.

These mechanisms are biologically plausible but have not been proven to be the cause of the clinical effect.

What do guidelines say?

International CMPA guidelines acknowledge the LGG research but do not recommend probiotics as a routine part of CMPA management. The prevailing view is that more independent trials are needed before advice changes.

In practice, a paediatrician or paediatric allergist may consider LGG for an individual infant with CMPA, particularly when the family asks about it. Any probiotic product used must be free of cow's milk protein, since some probiotic supplements use dairy-derived carriers.

Rhambac® GG Drops from ELMED Life Sciences contain LGG ATCC 53103 at 1 billion CFU per 6 drops. Before use in an infant with CMPA, the label and carrier ingredients should be checked with the doctor, and the drops are not a substitute for the prescribed formula or diet.

When should parents seek urgent help?

Call emergency services for any sign of anaphylaxis after milk exposure, such as difficulty breathing, swelling of the face or tongue, persistent coughing, pallor or floppiness. Seek prompt review for blood in stools, poor weight gain or feeding refusal. Never reintroduce cow's milk to an allergic infant at home without the allergist's plan. The broader evidence on LGG in children appears in LGG probiotic drops for infants and children.