Milk allergy and lactose intolerance are not the same condition. Many people with an intolerance think that they are allergic but the two involve an entirely different process.
True milk allergy involves a complex series of immune events generated by a protein. The symptoms caused from lactose intolerance come from a sugar.
Any protein found in dairy may cause an allergic reaction. The most common such protein is called alpha S1- casein. In true milk allergy a protein allergen starts a series of biochemical reactions that lead to mast cells releasing their intra-cellular contents. Histamine and other chemicals involved in allergy symptoms are released into the blood stream and travel to receptors where they bind and produce the visible reactions.
Symptoms generated depend on the amount of allergen exposure and the genetic profile. The protein causes specific immune cells to be produced. These antibodies attach to mast cells and make it easier for the mast cells to release their contents when the next exposure to the allergen occurs.
Many people will experience a progressive allergic reaction as subsequent exposure builds more immune cell mast cell complexes. With each exposure to the allergen protein, more mast cells are primed to react with the next exposure. Eventually a critical number of mast cells can become involved so that the next exposure causes a massive, life threatening release of histamine. This is called anaphylaxis and can be life threatening.
The enzyme that breaks down the dairy sugar lactose is called lactase. It is usually made in the bowel. There are a whole range of lactose intolerant syndromes that can affect the ability to digest dairy adequately. When a human body is unable to breakdown the lactose, it invariably results in some gastrointestinal distress, usually diarrhea.
Many people don’t have an absolute lack of lactase; they just don’t produce enough to meet all dietary requirements. This often leads to a delay in diagnosis. Some lactose is processed until reserves of lactase are depleted. Then symptoms present. People can’t identify milk products as the absolute cause because occasionally there is enough lactase to do the job.
In lactose intolerance there is no stimulation of the immune response. One has nothing to do with the other. People with an intolerance are not more likely to have dairy allergy. And conversely people with allergic problems are not more prone to any intolerance. Some people inherit both, most people inherit neither.
Each mammalian species has milk comprised of different proteins. So it is common to be allergic to dairy of one species but not another. One may be allergic to cow’s milk and not to goat’s. A baby may tolerate mother’s breast milk, but not formula made with cow’s milk.
More Infants Allergic
This allergy is age dependent. Between two and three years of age 2-4% of all children mount an allergic response to a dairy protein. By age three most have lost clinical reactivity. By adulthood the average is 0.1% to 0.5 % of the population is allergic to a milk protein.
Symptoms of Milk Allergy
Symptoms may appear immediately or sometime after exposure. The reaction may vary between people. In general reactions tend to progress in severity with repeated exposure.
Initially the reaction may be local and/or systemic.
- Itchy rash around the mouth
- Diarrhea (may contain blood)
- Runny nose/eyes
- Abdominal cramps
- The earliest exposures may produce itching with a few scattered hives. These may spontaneously resolve without treatment. With continued exposure to the allergen the reaction many increase. More hives and itching may persist for longer periods of time.
- Angioedema may develop with swelling of the lips, eyelids, tongue, hands and feet.
- Respiratory symptoms may include wheezing or cough from bronchospasm.
- In severe reactions the circulatory system may start to collapse resulting in shock with elevated pulse and decreasing blood pressure.
Risks and Related Facts
There are a few risk factors and related conditions associated with milk allergy.
- One risk that accompanies this allergy is other allergies. While a reaction to dairy is often the first allergy to present, it often heralds additional ones.
- 13%-20% of kids allergic to milk are also allergic to beef.
- Atopic dermatitis is a risk factor for this allergy. Atopic dermatitis is a chronic skin eruption based in the immune response. It is associated with food allergy in general but specifically to milk protein.
- There are two basic protein elements in milk that can cause allergies. Casein is from the more solid parts. Whey is the liquid part and a different protein.
- Family history increases the risks. This includes a family history of milk allergy but also hay fever, eczema, asthma or hives.
Cooking dairy products at high heat often will denature the protein; change the protein structure so that it will no longer cause a reaction. This will not always happen so it is best to avoid all potential sources of allergen. Foods that contain milk protein include:
- Malted Milk
- Anything containing whey and casein.
With a milk protein allergy, reading labels should become routine. Be wary of products prepared with milk such as baked goods and French toast. Even oatmeal can be prepared with it so it is best to check. Icings on cakes and cookies may contain dairy proteins even if the baked good does not.
Cow’s Milk Alternatives
A study done by Kaiser –Permanente in California, U.S.A. reported that very few of the children with documented dairy allergy were also allergic to proteins in soy-based milk. Their conclusions suggested soy as an alternative to animal derived milk products.
Rice milk is another alternative. Compared to cow’s, this has more carbohydrates but no milk protein or lactose. Commercial rice milk is fortified with B vitamins, calcium and iron.