Milk allergy

Milk allergy
Classification and external resources
A glass of pasteurized cow milk.
ICD-9	995.3, V15.02

A milk allergy is a food allergy, an adverse immune reaction to one or more of the constituents of milk from any animal (most commonly alpha S1-casein, a protein in cow's milk). This milk-induced allergic reaction can involve anaphylaxis, a potentially life-threatening condition.

Milk allergy is distinct from lactose intolerance.

Allergen

A person with milk allergy can be reactive to one of dozens of the proteins within milk. The most common one is alpha S1-casein.^[1]

Alpha S1-caseins differ between species. This explains why someone with an allergic reaction to sheep's milk cannot drink goat's milk but can drink breast milk without an allergic reaction.^[2]

Symptoms

The principal symptoms are gastrointestinal, dermatological and respiratory. These can translate to: skin rash, hives, vomiting, and gastric distress such as diarrhea, constipation, rhinitis, stomach pain or flatulence. The clinical spectrum extends to diverse disorders: anaphylactic reactions, atopic dermatitis, wheeze, infantile colic, gastroesophageal reflux (GER), oesophagitis, allergic colitis, headache/migraine, tachycardia, oral irritation, and constipation.

The symptoms may occur within a few minutes after exposure in immediate reactions, or after hours (and in some cases after several days) in delayed reactions.

Difference between milk allergy and lactose intolerance

Milk allergy is a food allergy, an adverse immune reaction to a food protein that is normally harmless to the non-allergic individual. Lactose intolerance is a non-allergic food sensitivity, and comes from a lack of production of the enzyme lactase, required to digest the predominant sugar in milk. Adverse effects of lactose intolerance generally occur after much higher levels of milk consumption than do adverse effects of milk allergy.

Lactose intolerance is considered the normal state for most adults on a worldwide scale and is not typically considered to be a disease condition.^[3]

Difference from milk protein intolerance

Milk protein intolerance (MPI) is delayed reaction to a food protein that is normally harmless to the non-allergic, non-intolerant individual. Milk protein intolerance produces a non-IgE antibody and is not detected by allergy blood tests. Milk protein intolerance produces a range of symptoms very similar to milk allergy symptoms, but can also include blood and/or mucus in the stool. Treatment for milk protein intolerance is the same as for milk allergy. Milk protein intolerance is also referred to as milk soy protein intolerance (MSPI)^{[citation needed]}.

Treatment

The main treatment for milk allergy is total avoidance of milk proteins. Products in addition to milk itself to be avoided by those with milk allergy include yogurt, butter, cheese, and cream. Goats' milk products may also need to be avoided. In extreme cases, rare, or un-cooked beef may also cause a mild reaction.

Ingredients that also denote that food product contains dairy milk include whey, casein, caseinate, butter flavor, lactic acid (lactic acid derived from dairy products), natural or artificial flavors such as milk or butter flavor, and sodium caseinate.

It is commonplace for milk or milk derivatives to be included in processed foods such as bread, crackers, cookies, cakes, prepared meats, "soy cheese", soups, gravies, crisps, margarine, and products labeled "non-dairy", such as whipped topping and creamer (non-dairy simply means less than 0.5% milk by weight^[4]).

It is also commonplace for milk derivatives, like casamino acid, to be in vaccines.

In some cases, heating the dairy product to force an exothermic chemical reaction can denature the proteins, (e.g. baking bread, or other baked goods). Only the ingredients that are chemically reacting will denature. Consequently, some allergic people are able to tolerate cooked foods that contain some milk.

It is important to note that many processed foods that do not contain milk may be processed on equipment contaminated with dairy foods, which may cause an allergic reaction in some sensitive individuals.

Milk avoidance and replacement for infants

Since milk protein may be transferred from a breastfeeding mother to an allergic infant, lactating mothers of allergic infants can simply be put on a dairy elimination diet.^[5] For formula fed infants, milk substitute formulas are used to provide a complete source of nutrition. Milk substitutes include soy based formulas, hypoallergenic formulas based on partially or extensively hydrolyzed protein, and free amino acid-based formulas.

Non-milk derived amino acid-based formulas, known as amino acid formulas or elemental formulas, are considered the gold standard in the treatment of cows milk allergy when the mother is unable to breastfeed.

Hydrolyzed formulas come in partially hydrolyzed and extensively hydrolyzed varieties. Partially hydrolyzed formulas (PHFs) are characterized by a larger proportion of long chain peptides and are considered more palatable. However, they are intended for milder cases and are not considered suitable for treatment of moderate to severe milk allergy or intolerance. Extensively hydrolyzed formulas (EHFs) are composed of proteins that have been largely broken down into free amino acids and short peptides. Casein and whey are the most commonly used sources of protein in hydrolyzed formulas because of their high nutritional quality and their amino acid composition.

Soy based formula may or may not pose a risk of allergic sensitivity, as some infants who are allergic to milk may also be allergic to soy. Also soy based formula are not recommended for infants under 6 months^{[citation needed]}. However, for infants with multiple allergies there are rice milk or oat milk based formulas available.

Milk substitution for children and adults

There are many commercially available replacements for milk for children and adults. Rice milk, soy milk, oat milk, coconut milk and almond milk are sometimes used as milk substitutes but are not suitable nutrition for infants. However, special infant formula based on soy, rice, almonds or carob seeds is commercially available.

On an avoidance diet, it may be possible to reduce the longer-term risk of calcium deficiency and osteoporosis by incorporating other sources of calcium, although the effect of calcium and vitamin D supplementation on osteoporosis is not always clear. There are fruit juices supplemented with calcium, sesame seeds, hemp seeds and some kinds of tofu. They may, however, have other effects on health.

Accidental exposure

Treatment for accidental ingestion of milk products by allergic individuals varies depending on the sensitivity of the allergic person. Frequently medications such as an Epinephrine pen or an antihistamine such as diphenhydramine (Benadryl) are prescribed by an allergist in case of accidental ingestion. Milk allergy can cause anaphylaxis, a severe, life threatening allergic reaction.

Milk allergies are common in infants but are usually outgrown within the first 2–3 years of life.

Desensitization

Desensitization, which is a slow process of eating tiny amounts of milk, until the body is able to tolerate more significant exposure, results in reduced symptoms or even remission of the allergy in some people. Sometimes this is done by putting a tiny amount of milk under the tongue, which is called sublingual immunotherapy. The other main approach for milk allergy involves eating a small amount of milk, perhaps baked into food.^[6] This is called oral immunotherapy. Sublingual immunotherapy may be somewhat safer but less effective.^[7] However, this may not be permanent and is still being researched.^[8][9]

Epidemiology

Milk allergy is the most common food allergy in early childhood. It affects somewhere between 2% and 3% of infants in developed countries, but approximately 85–90% of affected children lose clinical reactivity to milk once they surpass 3 years of age.^[10] The prevalence of milk allergy in adults is between 0.1% and 0.5%.^[11]

Between 13% and 20% of children allergic to milk are also allergic to beef.^[12]

Rate of hospitalization

Milk allergy is found to be associated with increased hospitalization rates and steroid use among children with asthma.^[13][14]

Prognosis

It is advisable to try and identify the offending agents early especially in patients with high risk and avoid them for a better long term prognosis.^[13]

See also

• Allergy
• Anaphylaxis
• Dairy product
• Human-milk bank
• Lactose intolerance
• List of allergies
• Medical emergencies

References

External links

• A muffin a day could keep milk allergy at bay
• Eating without Casein Practical guide to milk-free eating
• Milk Allergy at Food Allergy Initiative