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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.
Alpha S1-caseins do differ between species; but almost all commercially farmed animals produce antigenically similar milk. This explains why someone with an allergic reaction to cow's milk cannot drink sheep's or goat's milk, but can drink breast milk without an allergic reaction.
The allergy may be caused by the presence of specific milk antibodies or specific milk-sensitive lymphocytes. This gives rise to the two distinct forms of milk allergy: Antibody-mediated allergy, and Non-antibody mediated allergy.
The effects of antibody-mediated allergy are rapid in onset, evolving within minutes or seconds. These allergies always arise within an hour of drinking milk; but can occasionally be delayed longer when eating food containing milk as an ingredient.
The principal symptoms are gastrointestinal, dermatological, and respiratory. These can translate to: skin rash, hives, vomiting, and gastric distress such as diarrhea, rhinitis, stomach pain, wheeze, or full-blown anaphylactic reactions.
Milk allergy is a food allergy, an adverse immune reaction to a food protein that is normally harmless to the nonallergic individual. Lactose intolerance is a nonallergic 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.
Cows' milk protein allergy (CMPA) is delayed reaction to the milk protein that is normally harmless to the nonallergic, inintolerant individual. CMPA is mediated by T-lymphocytes, and is not detectable by allergy blood tests. Because it is not caused by antibodies, it can take several hours, or even up to 72 hours to produce a clinical effect. This makes it harder to diagnose, but also means that it cannot give rise to anaphylaxis, as there are no antibodies to trigger mast cells.
CMPA produces a range of symptoms: The principal symptoms are gastrointestinal, and dermatological. These can translate to: atopic dermatitis, vomiting, and gastric distress such as infantile colic, ]], gastroesophageal reflux, oesophagitis, diarrhea (typically in the very young), constipation (typically in older children), stomach pain, or flatulence. In some cases, particularly infants, it may also include blood and/or mucus in the stool.
Treatment for CMPA is very similar to that for antibody-mediated milk allergy. Some people may also have be allergic to soy protein(s), a combination called a milk soy protein allergy.
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 and sheep's milk almost invariably also need to be avoided. In extremely rare cases, rare or uncooked 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 (derived from dairy products), natural or artificial flavors such as milk or butter flavor, and sodium caseinate.
Milk or milk derivatives commonly are included in processed foods such as bread, crackers, cookies, cakes, prepared meats, "soy cheese", soups, gravies, crisps, margarine, and products labeled "nondairy", such as whipped topping and creamer (nondairy simply means less than 0.5% milk by weight).
In some cases, heating the dairy product 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.
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.
Since milk proteins 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. 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.
Nondairy-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 are available in partially hydrolyzed and extensively hydrolyzed varieties. Partially hydrolyzed formulas 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 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 poses a risk of allergic sensitivity, as some infants who are allergic to milk may also be allergic to soy. Formula of any kind is not recommended for infants under 6 months.
Many commercially available replacements for milk for children and adults exist. Rice milk, soy milk, oat milk, coconut milk, almond milk, or milk based on carob seeds are sometimes used as milk substitutes.
On an avoidance diet, reducing the longer-term risk of calcium deficiency and osteoporosis is possible by incorporating other sources of calcium, although the effect of calcium and vitamin D supplementation on osteoporosis is not always clear. Fruit juices supplemented with calcium, sesame seeds, hemp seeds and some kinds of tofu are other calcium sources.
Treatment for accidental ingestion of milk products by allergic individuals varies depending on the sensitivity of the 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.
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, sublingual immunotherapy. The other main approach for milk allergy involves eating a small amount of milk, perhaps baked into food. This is called oral immunotherapy. Sublingual immunotherapy may be somewhat safer, but less effective. However, this may not be permanent and is still being researched.
Milk allergy is the most common food allergy in early childhood. It affects between 2% and 3% of infants in developed countries, but 85–90% of affected children lose clinical reactivity to milk once they pass three years of age. The prevalence of milk allergy in adults is between 0.1% and 0.5%.
Between 13% and 20% of children allergic to milk are also allergic to beef.
Identification of the offending agents early is advised, especially in patients with high risk, and they must avoid them for a better long-term prognosis.
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