Milk Allergies

A person of any age can have a milk allergy, but milk allergies among infants are very common.  It is estimated that around two to three percent of babies have milk allergies, although most outgrow it.

According to the Food Allergy and Anaphylaxis Network, cow’s milk is one of the top eight foods that cause allergic reactions in babies. A milk allergy occurs when the immune system mistakenly sees the milk protein as something the body should fight off. This starts an allergic reaction, which can cause an infant to be unsettled and irritable, and cause an upset stomach and other symptoms. Most kids who are allergic to cow’s milk also react to goat’s milk and sheep’s milk, and some of them are also allergic to the protein in soy milk.

Milk allergy symptoms can develop in both formula-fed and breastfed babies. Formula-fed babies drink cow’s milk directly, since it provides the basis of most commercial baby formulas, so these babies are much more likely to develop a milk allergy and the symptoms that accompany it. However, even when a mother exclusively breastfeeds her baby, the child may react to the small amount of milk protein that comes from her diet. In addition, some breast-fed babies develop sensitivity to the cow’s milk protein in their mothers’ diets, but they don’t start developing milk allergy symptoms until they drink cow’s milk directly. Infants who are breastfed have a lower risk of developing a milk allergy than those who are formula fed. But researchers don’t fully understand why some develop a milk allergy and others don’t, though it’s believed that in many cases, the allergy is genetic.

Symptoms

Babies may develop certain symptoms within moments of exposure to cow’s milk. Such symptoms include irritability, wheezing, vomiting, hives and bloody diarrhoea. These more immediate symptoms are less likely to occur than slower onset symptoms, which the baby can experience seven to 10 days after exposure to cow’s milk, according to KidsHealth.org. These more common symptoms include diarrhoea (possibly with blood), abdominal cramps, vomiting, coughing, gagging, runny nose, skin rash and colic.

Cows’ milk protein allergy (CMPA)

Symptoms of cows’ milk protein allergy (CMPA) range from mild e.g. eczema (skin rash) and rhinitis (runny nose), to severe e.g. enteropathy (gastrointestinal symptoms) and anaphylaxis (life-threatening allergic reaction).

• The diagnosis will be made by a doctor or paediatrician, and will usually involve taking blood samples.
• These children should be breastfed exclusively for the first six months of their lives. However, many mothers cannot, or choose not to breast feed, resulting in infant formula supplementing, or replacing, breast milk. When parents supplement or replace breast milk, they should avoid giving conventional cows’ milk or soybean based formula. Soybean formula can itself be quite allergenic and should rather be reserved for children with lactose intolerance or given on a doctor’s recommendation. However a proportion of infants with cows’ milk protein allergy will tolerate soy formula.
• Parents should also delay giving weaning foods to a CMPA child until the end of the fourth month, or even better, the sixth month. When weaning, they should avoid foods with milk proteins. Infant cereal should rather be mixed with breast milk (or soy formula, if tolerated), not with cows’ milk.

Lactose Intolerance

Lactose intolerance is different from milk allergy. It is due to either an acquired or an inherited deficiency of lactase. The gut mucosa normally produces an enzyme, called lactase, that catalyses the breakdown of lactose. When people who are lactase-deficient drink milk, which contains lactose, they develop abdominal cramps, abdominal distension or bloating, diarrhoea and flatulence.

• Acquired lactase deficiency: if the intestinal mucosa is damaged, for example in severe gastro-enteritis or some other viral or bacterial infection of the gut, a temporary lactose intolerance can develop – this usually clears up if milk and milk products are avoided and the mucosal layer is given time to repair itself
• Inherited intolerance: this can be a familial trait. It also occurs more commonly in certain population groups, e.g. Native American Indians and Hispanics. These people are best advised to avoid milk. However research has shown that many lactose-intolerant individuals can tolerate approximately 12 grams of lactose (the amount of lactose in one glass of milk) a day. In this case products with low levels of lactose, but high levels of calcium, are preferred e.g. yoghurt, cottage cheese and matured cheeses.

As lactose free diets may compromise calcium absorption, and may affect the normal flora and physiological functioning of the infant’s colon, they should not be implemented unless there is a clear indication to do so. This should preferably be on a doctor or a dietician’s advice. Similarly, lactose free formulae should only be used if there is a proven lactose intolerance. A simple stool test can usually identify lactose intolerance and this should be carried out if there is any doubt as to the diagnosis.

Atopic disease

Atopic diseases are due not to infection but rather a manifestation of an allergic condition:

• Allergic bronchial asthma – frequent cough with breathing difficulties, wheezing and shortness of breath.
• Allergic rhinitis (hayfever) – this is a reaction to pollen, domestic pet hairs and/or house-dust mites with frequent colds and runny noses, frequent sneezing, and, in children, frequent nose-rubbing and itchy nose. It can be seasonal or perennial (all year-round).
• Atopic dermatitis/eczema – an itchy red rash that is usually found in infants on the cheeks, forehead, chest and arms. In older children and adults it is usually on the back of the knees, front of the elbows (in the crease), finger joints and calves.
• Food allergies – certain foods produce symptoms such as diarrhoea, stomach ache, flatulence and/or one or more of the above-mentioned symptoms (i.e. asthma, hay fever or eczema).

Research now indicates that exposure to allergens that trigger childhood allergies can lead on to atopic diseases. Up to 50% of children with atopic dermatitis or food sensitisation/allergies in infancy will maintain this early allergy throughout much of their lives, or will eventually develop respiratory diseases. However, research shows that if babies’ diets are modified and various environmental factors are controlled, then the onset of these allergies can be delayed or diminished and possibly even prevented.

Infants at risk for allergy

As there is a strong genetic factor involved in atopic diseases, there is usually a positive family history of allergy. A simple way for the pharmacist/pharmacy assistant to assess this is to get the patient to fill in a family questionnaire, checking if mother, father or any siblings has had (as a child) or still has:

• atopic dermatitis (eczema).
• allergic bronchial asthma/allergic bronchitis.
• allergic rhinitis e.g. hayfever/year-round allergic (runny) cold.
• food allergy (not simple intolerance)

A positive response in any one of the categories indicates an allergic predisposition in the family. More than one parent/sibling with a positive history indicates an elevated allergic risk. Although the family history gives some idea of allergic risk, there is no absolutely reliable way to measure the risk. About 5-15% of all newborn babies will eventually develop an allergic reaction even if there is no family history of allergies.

Decreasing the risk of allergies in newborns

There are a number of simple, practical and inexpensive measures that the pharmacist can advise mothers/childminders to implement. These will help to decrease the chances of allergies developing and may even prevent them. As food allergies have been shown to play a major role in the development of atopic (allergic) diseases in infants and children, modifying the infant’s diet can help to prevent the onset of atopy.

• Encourage exclusive breast feeding for at least the first four to six months of life as this may greatly decrease the incidence of allergic manifestations, especially atopic eczema and the gastrointestinal symptoms related to cows’ milk.
• If exclusive breast-feeding is not possible, then it is recommended that a hypoallergenic (H.A.) formula e.g. Nan H.A.® is used for supplementary feeds in infants at risk of developing atopic disease. There is no conclusive evidence to support using a hypoallergenic formula in infants where there is no family history of allergic disease – cost would probably be a determining factor.
• When supplementing or replacing breast milk, avoid giving conventional cows’ milk or soybean based formula. Soybean formula can itself be quite allergenic and should rather be reserved for children with lactose intolerance or given on a doctor’s recommendation. However a proportion of infants with cows’ milk protein allergy will tolerate soy formula.
• Delay the introduction of ?? solid foods until the end of the fourth, or preferably the start of the sixth, month.
• Avoid strongly allergenic foods for the first year of life, e.g. eggs, fish, citrus fruits, wheat products, nuts/peanuts, soybean products. Add one new food at a time, at weekly intervals, so any adverse effects can easily be identified.
• By the time the child is seven months old, complementary feeding can be more varied, but cows’ milk should still be avoided – rather use a follow-up formula or, if necessary i.e. risk of allergy, a hypoallergenic (H.A.) formula.
• Avoid baby-care products that contain cows’ milk protein and that are highly perfumed.

Food re-challenges

Allergic reactions to a particular food protein may disappear in infants and children after several months or years of avoiding the allergen, especially in children with cows’ milk protein allergy. It is often worthwhile doing controlled re-challenges at regular intervals – parents should be advised to discuss this with their doctor so it is done correctly. This will help to prevent prolonging avoidance diets unnecessarily

References on request

REFERENCES

1. Exl B-M, Wallrafen A.  Allergy prevention in infants – Practical advice (English Translation): The German Allergy and Asthma Association, Help Medical.

IMC de Carvalho B.Soc.Sc.Hons.IMM