The Etiology of Alpha Gal Allergy


Frequently Asked Questions

What exactly is this mammalian meat allergy?

When certain people are bitten by ticks or chiggers, the bite appears to set off a chain of reactions in the body.  One of these reactions is the production of an allergic class of antibody that binds to a carbohydrate present on meat called galactose-alpha-1,3-galactose, also known as alpha-gal.  When a person with the alpha-gal antibody eats mammalian meat, the meat triggers the release of histamine.  Histamine is a compound found in the body that causes allergic symptoms like hives, itching and, in the worst case, anaphylaxis (a reaction that leads to sudden weakness, swelling of the throat, lips and tongue, difficulty breathing and/or unconsciousness).

In addition to the classic allergy symptoms, some of our patients report significant gastrointestinal distress or gynecological symptoms. These symptoms can take the form of abdominal cramping and pain, heartburn, diarrhea, nausea or vomiting and in some cases uterine cramping with spotting. It is not uncommon for a patient who has anaphylaxis to lose consciousness while moving their bowels.  Some patients have reactions that are characterized almost entirely of GI or gynecological symptoms while others may not experience these types of symptoms at all.

This allergy is different from other food allergies like peanut allergy in that the response is delayed.  Unlike someone with a peanut allergy who has an immediate reaction when they eat a peanut, people with the alpha-gal allergy usually do not start having symptoms until several hours after they eat meat.

What exactly is mammalian meat?

Mammalian meat is any meat that comes from a mammal.  This includes beef, pork, lamb, venison, goat and bison.  Chicken, turkey and fish are not mammals and therefore do not have alpha-gal.

Do humans have alpha-gal?

No, we do not.  During the evolution of our species, the enzyme that leads to the production of alpha-gal was inactivated.  The only mammals that do not have it are humans, old world monkeys and great apes.

I think I have this allergy but I only have a reaction after eating beef.  Is that possible?

Yes.  We have seen many people who only react to only one or two of the mammalian meats.  We do not know for sure exactly why this happens.  We believe that there is a connection between the fat content of the meat and the way the body reacts to it.  Meats with more fat like hamburgers seem to cause more reactions than lean meats like venison.

Why do I have this allergy?

We do not yet know why certain people develop this allergy while other people do not. We believe that bites from ticks (either adult or nymph) can cause some people to develop this antibody response. Fortunately, it seems as though the antibody levels drop over time in patients who avoid additional tick bites. How long this takes varies widely for each individual.

How many other people have this allergy?

To date, we have heard of several thousand people from across the United States and abroad who have developed delayed hives, swelling and anaphylaxis 3-6 hours after eating mammalian meat.

How do I get tested for this allergy?

There is a commercial test available for the mammalian meat allergy through the lab company ViracorIBT.  You will need to arrange to get your blood drawn at your primary care doctor’s office or another local clinic.  The clinic should draw one “red top” tube.  In order to have the test done, you need to include a print-out of this form which has to be signed by a doctor, nurse practitioner or physician’s assistant.    On page 5 under “Mammal/Fowl” you will see a test called “Alpha-Gal”.  Check off the box to the right of “Alpha-Gal” under “IgE”.  The test costs $37.50.

What do the test results mean?

You will receive a number that indicates the amount of alpha-gal specific antibody you have in your blood.  Any number above 0.35 is considered to be positive.  A higher number does not necessarily indicate worse symptoms but, in general, people with lower numbers (2-3 IU/mL) seem to be able to tolerate small amounts of lean meat without much difficulty.

What is the treatment?

The only treatment that is available right now is to avoid mammalian meat.

Will I ever be able to eat a ham sandwich/burger/lamb roast again?

There are some initial signs that the alpha-gal antibody level goes down over time, especially if you are able to avoid tick/chigger bites.  If you test positive and are able to avoid bites for several months, you might consider being re-tested after that period to see if your antibody level has decreased.

What about dairy?

There is a small amount of alpha-gal in dairy products (milk, yogurt, cheese, butter, cream, etc.).  Most people who test positive for this allergy are still able to eat dairy without problems.  However, if you have any lingering symptoms or just do not feel “right” after giving up mammalian meat, you might consider avoiding dairy as well.  Some people with really bad reactions have found that to be helpful.  If you are feeling fine, we suggest keeping milk in your diet as it may offer some amount of tolerance to alpha-gal.

What about gelatin?

Gelatin is a substance made from animal products.  It is in many foods including certain candies, marshmallows and other desserts.  Some medications are also put in gelatin capsules.  Gelatin does have alpha-gal in it.  We have heard from at least one person who had a reaction after eating candy with gelatin in it.  If you are particularly sensitive to mammalian meat products, you might consider avoiding gelatin.

What about protein powders?

We have heard from at least one person who had a reaction after eating a protein powder made from whey protein isolate.  Whey is a substance found in milk.  The person who reacted to it has not experienced reactions with any other dairy products.

Are there any medications that contain alpha-gal?

Cetuximab, a cancer drug, contains alpha-gal and has caused reactions in many people with this allergy.  We know that at least one pancreatic enzyme replacement drug (Creon 10) contains alpha-gal.  In addition, there are two intravenous fluid replacement products, gelofusine and haemaccel, that are known to contain alpha-gal.  Neither of theseIV fluid replacement products are currently used in the United States.

In terms of supplements, we do know of one study participant who had a reaction after using an adrenal supplement produced from lamb products.  Many adrenal supplements are made directly from mammalian adrenal glands.  For people with this allergy, we recommend checking the label for mammalian products before taking any adrenal supplements.

Is it possible that the allergy is caused by hormones, pesticides or other chemicals found in meat?

While certain people with this allergy report having fewer or less severe reactions after eating all natural meat, we have also heard from people who have had severe reactions after eating wild meat from animals they hunted or all natural meat from reputable sources.  It is possible that the chemicals found in industrially produced meat exacerbate certain people’s reactions but the connection is unclear at this time.

Can I still donate blood if I have this allergy?

Yes.  We do not believe that you can “share” this allergy by giving blood.

I would like to make an appointment at the University of Virginia allergy clinic to see a member of your team about this allergy.  How do I do that?

To schedule an appointment with an allergist who has experience working with alpha-gal patients please contact the UVA Allergy Clinic directly by calling (434) 924-2227.  You can also call the toll free patient referral line at 1-800-251-3627 and ask to make an appointment with one of our allergists.

What kind of research are you doing?

Right now, we are investigating the role of tick bites in initiating the IgE response that leads to mammalian meat allergy. Additionally, we are researching the mechanism behind the delayed appearance of symptoms.

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