A strange new food allergy called “alpha-gal syndrome,” also referred to as alpha-gal allergy, is on the rise, particularly in areas of the United States with endemic Lyme disease. Read on to learn why you should be aware of alpha-gal syndrome if you've experienced a tick bite and why identifying and treating this food allergy plays a crucial role in recovery from chronic tickborne illnesses.
Alpha-gal syndrome (AGS) is a type of allergy to mammalian meat. Mammalian meat includes beef, bison, pork, lamb, wild game, rabbit, and unusual meats from other mammals, such as kangaroos. AGS is unique because, unlike most food allergies, which involve the immune system mistakenly identifying specific proteins in foods as harmful, AGS is an allergy to a sugar molecule or carbohydrate found in mammalian meat called galactose-alpha-1-3-galactose.1 The immune response to this molecule, as opposed to a protein, makes AGS unique amongst food allergies.
People are not born with AGS, it most often develops in adulthood, though children can acquire the allergy, as well. The primary identified cause of AGS is a tick bite; more specifically, bites from the Lone Star tick or black-legged tick.2 This finding explains why AGS is most common in regions where the Lone Star and black-legged ticks prefer to live, including the southeastern US, Texas, the Midwest, and New York.3
Ticks appear to synthesize alpha-gal carbohydrate inside their bodies with the help of enzymes called galactosyltransferases; it may be this endogenously-derived alpha-gal that triggers an immune response in the individual bitten by a tick. Interestingly, bites from ticks that carry the bacterium Anaplasma phagocytophilum, the cause of disease Anaplasmosis, may be more likely to cause AGS because Anaplasma increases the tick’s level of alpha-Gal.4
When an individual is bitten by a Lone Star or black-legged tick, or presumably any vector-containing alpha-gal carbohydrate in its saliva, the individual's immune system can start to react to alpha-gal, creating antibodies designed to attack the alpha-gal molecule. These antibodies are called “anti-α-Gal IgE antibodies.” Anti-α-Gal IgE antibodies break oral tolerance or the active regulatory immune response that allows our bodies to tolerate ingested foods.5 This breakdown of oral tolerance causes the body to react to food allergens, namely the alpha-gal carbohydrate in mammalian meat.5 The tick bite also skews the immune response more towards a T helper 2 (Th-2) response, the type of immune response more correlated with allergies. AGS differs from other IgE-mediated food hypersensitivities in that the response to mammalian meat occurs 3-6 hours after consumption, rather than immediately post-consumption.6
Once the reaction starts, the individual's immune system may also begin to cross-react to alpha-gal present in dietary mammalian meat, releasing more alpha-gal antibodies. The release of these antibodies causes an inflammatory response, leading to the symptoms of AGS.
Interestingly, having anti-alpha gal antibodies inside your body offers a protective response against infection with pathogens that contain the alpha-gal carbohydrate because quick recognition of the carbohydrate molecule by the immune system would theoretically allow the immune system to recognize that a tick bite has occurred and thus target pathogens transmitted via the bite. The tradeoff is that, for this protection, the body must contend with a new food allergy.7 In my clinical experience, I've found that AGS can be attenuated in individuals over time, provided they are treating chronic infections and engaging in treatments, diet, and lifestyle practices that regulate the immune system.
Interestingly, alpha-gal syndrome can occur both in atopic individuals (people with a tendency to allergies) and non-atopic individuals, or those with no prior history of asthma or food or environmental allergies.10, 11
Research suggests that factors that increase intestinal permeability (“leaky gut”), such as alcohol consumption and exercise, potentiate the severity of an AGS reaction by enhancing the translocation of alpha-Gal from the intestine into the bloodstream.12 Based on this line of research, it follows that other factors that promote leaky gut, such as gluten consumption and emotional stress, may also intensify AGS reactions.
AGS exists on a spectrum; as such, the symptoms of AGS vary. While some individuals with AGS may manifest an anaphylactic reaction upon consuming beef, another individual may manifest gut discomfort and fatigue. The spectrum of responses in AGS can make it difficult to assess. However, according to a recent article published in The Journal of Allergy and Clinical Immunology, “the a-Gal syndrome should be considered as an explanation for allergic symptoms, including abdominal pain, related to red meat at any age, regardless of atopic history, ABO blood group, symptom severity, and timing of symptom onset.”13
The most common symptoms of AGS include:
AGS reactions are often delayed, beginning 3-8 hours after eating mammalian meat or meat-derived products. AGS may also “unmask” mast cell issues, causing people to demonstrate symptoms consistent with mast cell activation syndrome (MCAS).
The diagnosis of alpha-gal allergy is based on a clinical history of delayed reactivity to mammalian meat and a blood test that assesses reactivity to galactose-alpha-1-3-galactose. A positive blood test (>0.1 IU/mL) for IgE to alpha-gal establishes the diagnosis.14 Notably, skin prick tests for allergies to beef or pork are not reliable for diagnosing AGS.
Both Quest and LabCorp offer testing for the alpha-gal syndrome. It is essential to ensure that you're using the proper test. You do NOT want to test for alpha-galactosidase, which sounds similar but is an entirely different marker. The Quest Alpha-gal Panel Test Code is 95241 or 91380, and the LabCorp Alpha-gal Panel Test Number is 650003.
Importantly, only 1-8% of individuals sensitized to alpha-gal have clinical alpha-gal syndrome, meaning they neatly fit the clinical diagnostic criteria for AGS.14 This means that many people who test positive for alpha-gal IgE do not exhibit apparent symptoms after eating red meat. However, because the symptoms of AGS exist on a spectrum, a portion of these people may react to some medications or medical products containing alpha-gal, such as bioidentical porcine-derived thyroid hormone medication and adrenal glandular supplements or experience symptoms after eating mammalian organs, which have more alpha-gal than mammalian muscle meats.15
The first step in treating alpha-gal allergy is to remove mammalian meat products from the affected individual's diet for some time. The length of this elimination period is at the discretion of the healthcare provider. It will depend on whether the underlying factors contributing to AGS – chronic tickborne infections, immune dysregulation, compromised gut health – are simultaneously being addressed alongside the mammalian meat elimination.
If you test positive for alpha-gal syndrome, you will need to avoid the following mammalian meat-derived foods:
People with alpha-gal may also need to temporarily avoid the following supplements, which contain ingredients derived from mammalian meat:
Finally, carrageenan is a source of alpha-gal, though it comes from seaweed, not mammalian meat. Carrageenan is present in many processed foods, so you’ll want to watch out for this item on ingredient lists.
People with AGS can generally eat the following foods:
In clinical practice, I’ve found that a Paleo template diet works best for most individuals with tickborne infections and allergies, so it is an ideal dietary template for those with AGS. A knowledgeable nutritionist and health care team can help you determine the appropriate personalized diet for your unique needs.
Making dietary changes is beneficial for those with AGS because it allows the body to calm down the inflammatory response, making for smoother sailing during tickborne infection treatment. Many people find it helpful to work with a functional medicine practitioner who has experience in repairing and healing the gut in order to return to optimal health as quickly as possible.