Could some cases of irritable bowel syndrome (IBS) be due to a lesser-known condition called alpha-gal syndrome (AGS)? You may never have heard of alpha-gal, but its symptoms of stomach pain, nausea, and diarrhea can mimic IBS. Alpha gal syndrome is commonly known as an alpha-gal allergy, “sudden meat allergy,” or “red meat allergy.” But, unlike most food allergies, the symptoms of alpha-gal syndrome are not typically immediate and instead start 4-6 hours after eating. This makes identifying the association between symptoms and diet challenging and raises the odds of it being confused with IBS. And, because not only meat causes a reaction in AGS, the picture can be puzzling.
But why would a person who has been able to eat meat their entire life suddenly experience stomach pain, rashes, or even life-threatening anaphylaxis after even a tiny bite of meat or an animal-derived product such as a gelatin vitamin capsule?
Let’s talk about what AGS is, how it is diagnosed, and what to do about it.
What is Alpha-gal?
Alpha gal is a compound found naturally in mammalian meat, including beef, pork, lamb and deer. People do not normally react to the alpha-gal compound found in meat, but the bite of a tick can change things.
The tick’s saliva contains the same alpha-gal molecule as meat. When a tick bites a person, the alpha-gal molecule in the saliva enters the person’s body. Now, the person’s immune system goes to work to protect the person from the alpha-gal molecule, which is seen as a “foreign invader.” From that moment forward, the person reacts to the alpha-gal protein.
And, because it is the same compound as in meat, a person can no longer tolerate beef, pork, lamb, venison, and other red meats because the body sees it as “foreign” like a virus. The body starts an immune reaction to try to protect the person from the alpha-gal in the meat.
The body can’t tell the difference between the alpha gal in the meat vs. that from the tick.
Alpha gal syndrome is the reaction that occurs after a person is sensitized to the alpha-gal compound.
Symptoms of Alpha-Gal Syndrome
Symptoms typically occur 3-6 hours after eating meat and range from mild to life-threatening. *
Because symptoms begin at any age, in someone with no prior problems, the connection to meat or meat ingredients is not always made. And, since AGS starts after a tick bite, symptoms may be mistakenly blamed on tick-borne illnesses such as Lyme disease. Some people test positive for sensitization to alpha-gal but have no symptoms, the reason for this is not yet understood (8).
You can have one or more of the following symptoms. It is not uncommon to have isolated digestive symptoms without any other type of symptoms.
- Stomach pain
- Difficulty breathing
- Runny nose
- Severe anaphylaxis
*Symptoms can occur immediately, but this is less common.
It Can Mimic IBS
AGS causes digestive problems
A 2021 study in the journal Gastroenterology looked at whether or not people with AGS could have ONLY digestive symptoms. The answer was yes! In this study, three-quarters of the patients had resolution of their “IBS” symptoms with the removal of meat and meat products. If this is the case, before the diagnosis of IBS is given, all patients should have a thorough history taken, which includes questions about tick bites. And, the testing for alpha-gal IGE should be considered.
Related Article-What Is SIBO? How Is It Related To Stomach Problems and IBS?
How Common Is It?
The number of cases has risen from 12 in 2009 to 34,000 in 2019.
In the US, the alpha-gal syndrome is most common in the southeastern states where ticks causing alpha-gal allergy are endemic. Estimates show about 15-30% of people living in endemic areas have antibodies to alpha-gal. Overall it is estimated that 3% of the US population tests positive for alpha-gal antibodies. That is nearly 10 million people!
Australia has the most reported cases worldwide, but the syndrome also occurs in Asia, Africa, and Europe. In these countries, the tick species causing the issues vary.
Diagnosis Of Alpha-Gal Syndrome
Alpha gal syndrome is diagnosed by blood tests and a history of a tick bite correlating with the onset of symptoms.
The following criteria are currently used for diagnosis:
- Reactions occur after eating mammalian meat without problems for many years, onset can be at any time.
- Reactions range from mild to severe and vary person to person
- Reactions start 3-8 hours after eating non-primate mammalian meat. Reactions may also occur after consumption of dairy, gelatin, or other mammalian-derived products containing alpha-gal for some patients.
- Positive testing for alpha-gal IgE (>0.1 IU/mL)
- Improvement of symptoms when adhering to an appropriate avoidance diet
Which Ticks Are To Blame?
The lone star tick and the black-legged tick are responsible for most cases in the U.S.
In the United States, these are most common in the Southeast, but the tick population is growing. This is attributed to climate change and an increase in the deer population. In Europe, the castor bean tick is the culprit, and in Australia, the blame is placed on the paralysis tick or Ixodes tick (1).
Lyme Disease & Other Tick Born Diseases
Because the symptoms of AGS occur after a tick bite, confusion with Lyme disease symptoms occurs.
Lyme disease diagnosis can be difficult, and laboratory evaluation is not perfect. Because of this, some people are diagnosed with Lyme disease based on the history of a tick bite and new symptoms. You see the problem.
If a person is mistakenly diagnosed with Lyme disease, and the reason for their new symptoms is AGS, the treatment is drastically different from the treatment for Lyme disease. Lyme disease requires antibiotic treatment. If the problem is AGS, the treatment is dietary avoidance and may only be temporarily needed. Antibiotics are not required in AGS, and their long-term use can cause adverse effects on the microbiome and immune system.
Consider AGS, Lyme, and other tick-borne diseases if new-onset symptoms occur after a tick bite.
An epi-pen should be prescribed to anyone diagnosed with AGS.
Treatment involves educating the patient on avoiding meat and products containing ingredients derived from mammals. This includes medications and supplements which are commonly made in gelatin-derived capsules.
Avoiding products that contain alpha-gal is essential. Unlike most allergies, the reaction to alpha-gal tends to decrease with time. However, if additional tick bites occur, the immune response can increase and become more severe (2, 3).
All people with alpha-gal allergy should be followed by an allergist and be checked routinely for blood levels and ongoing symptoms.
Foods To Avoid With An Alpha Gal Allergy
All products from mammals must be avoided
A person’s response needs to be determined by working with an allergist. This is especially important if the reactions are severe.
In the meantime, it is essential to avoid any food, medication, supplement, or health and beauty product derived from meat.
Some people are able to tolerate small amounts of products containing alpha-gal but the level should be determined in conjunction with a doctor. Trying small amounts without guidance may prove dangerous.
Foods to avoid:
- Milk – only avoid if it causes a reaction (4)
- Bison (Buffalo)
- Lard – common in pastries and some Latin food
- Gelatin ( Jello, Marshmallows, jelly beans, candy, capsules for vitamins and medications)
A more complete list of foods containing alpha-gal is provided at this link by the alpha-gal organization.
Foods That Are Safe For A Person With Alpha Gal Allergy
- Fish and poultry products are safe
- Herbs and spices
Medications To Avoid If You Have Alpha-Gal Syndrome
Medications may contain gelatin or other animal by-products. It is important to discuss safe medicines with the pharmacist.
The following medications are NOT recommended for anyone with alpha-gal syndrome.
- Heparin (4)
- Cetuximab (5)
- Vaccines that contain gelatin ((6)
- Any supplement in a gel capsule-these are common
- Any supplement or medication with magnesium stearate. This includes Tylenol, naproxen, lisinopril, clonidine, Vicodin. Ask the pharmacist for an ingredient list of any medication you must take.
Alpha Gal And Alcohol
Most alcoholic drinks do not contain animal byproducts and are approved to enjoy, even with a diagnosis of AGS. However, drinking alcohol simultaneously with accidental ingestion of a mammalian product can lead to a faster, more severe reaction. (7).
Prevention Of Alpha Gal Syndrome
To date, the only known way to prevent alpha-gal syndrome is to prevent tick bites.
- Wearing full-coverage clothing
- Use tick repellent
- Check for ticks as soon as you return indoors
- Remove the tick immediately if found
Related Article-Mast Cell Activation Syndrome: Symptoms, Diet, Treatment
Where To Find Help
Seek out help from your primary care doctor or an allergist. A patient support network can be found at Alpha-gal Information,, a non-profit aimed at providing education on AGS.
- Tick Saliva and the Alpha-Gal Syndrome: Finding A Needle In A Haystack
- Alpha-gal syndrome masquerades as IBS
- Successful beef desensitization in 2 adult patients with a delayed-type reaction to red meat
- Diagnosis and management of patients with the α-Gal syndrome
- Discovery of Alpha-Gal-Containing Antigens in North American Tick Species Believed to Induce Red Meat Allergy
- Diagnosis & management of alpha-gal syndrome:lessons from 2,500 patients