Alpha Gal and the Lone Star Tick

Image Credit: USGS Bee Inventory and Monitoring Lab / Flickr. This image has been modified.

How a Tick Bite Can Lead to Food Allergies

In the beginning, Aristotle defined two forms of life on planet Earth: plants and animals. Two thousand years later, the light microscope was invented and we discovered tiny, single-celled organisms like amoebas. Then, the electron microscope was invented and we discovered better characterized bacteria. Finally, in 1969, biologists recognized fungi as a separate category, and we’ve had at least five kingdoms of life ever since.

In my video, Higher Quality May Mean Higher Risk, I talk about the potential downsides of consuming proteins from within our own kingdom, such as the impact our fellow animal proteins can have on boosting our liver’s production of a cancer-promoting hormone called IGF-1.

In Eating Outside Our Kingdom, I talked about other potential advantages of preferably dipping into the plant and mushroom kingdoms for dinner, not only from a food safety perspective (we’re more likely to get infected by animal pathogens than Dutch Elm Disease), but because of the potential for cross-reactivity between animal and human proteins. Our immune system is more likely to get confused between a chicken leg and our own legs than it is with a banana, so there may be less potential to trigger an autoimmune reaction, like degenerative brain diseases or inflammatory arthritis (See Diet & Rheumatoid Arthritis). In attacking some foreign animal meat protein, some of our own similarly composed tissues may get caught in the crossfire.

It’s not just proteins. If you remember the Neu5Gc story (see Inflammatory Meat Molecule Neu5GC), sialic acid in other animals may cause inflammation in our arteries (see  Nonhuman Molecules Lining Our Arteries) and help breast tumors and other human cancers to grow (see How Tumors Use Meat to Grow: Xeno-Autoantibodies). Now a new twist has been added to the story.

The reason Neu5Gc triggers inflammation is because humans lost the ability to make it two million years ago, and so when our body is exposed to it through animal products, it’s treated as a foreign molecule, causing inflammation. But there’s also another oligosaccharide called alpha-gal that humans, chimps, and apes lost the ability to make 2 million years ago, but is still made by a variety of animals, including many animals we eat.

Anti-gal antibodies may be involved in a number of detrimental processes that may result in allergic, autoimmune, and autoimmune-like diseases, such as auto-immune thyroid disorders. We see higher levels of anti-gal antibodies in Crohn’s disease victims. These antibodies even react against about half of human breast tumors, and we can find them in atherosclerotic plaques in people’s necks. However, those are all mostly speculative risks. We do know that alpha-gal is a major obstacle to transplanting pig organs, like kidneys, into people, because our bodies reject alpha-gal as foreign. In fact, alpha-gal is thought to be the major target for human anti-pig antibodies.

It’s interesting that if we look at those that abstain from pork for whatever reason, they have fewer swine-specific immune cells in their bloodstream. Researchers speculate that oral intake of pork could ferry swine molecules into the bloodstream via gut-infiltrating lymphocytes to prime the immune response. So we can have an allergic reaction to eating pig kidneys too, but such severe meat allergies were considered rare, until an unusual report surfaced. First described in 2009, the report included details on 24 cases of meat allergies triggered by tick bites.

Within a year, it was obvious that the cases should be counted in hundreds rather than dozens. By 2012, there were thousands of cases across a large area of the southern and eastern U.S., and new cases are now popping up in several countries around the world.

The culprit, the lone star tick, so-called because females have a white spot on their back, are famous for causing Masters’ disease, a disease similar to Lyme syndrome, also known as STARI (southern tick associated rash illness). But thanks to the lone star tick steadily expanding its range (even as far as Long Island, NY), it’s not necessarily just so Southern any more.

What is the relevance of tick bites to the production of allergy-causing anti-meat antibodies to alpha-gal? Good question. What we know is that if you get bitten by one of these ticks, you can develop an allergy to meat (See Alpha Gal and the Lone Star Tick). This appears to be the first example of a response to an external parasite giving rise to an important form of food allergy. We don’t know the exact mechanism, but it may be because there’s something in the tick saliva that’s cross-reacting with alpha-gal, or because the tick is injecting you with animal allergens from its last meal.

What role may these tick-bite induced allergies play in the development of chronic hives and other allergic skin reactions in children? See Tick Bites, Meat Allergies, and Chronic Urticaria.

Here’s some videos unearthing the IGF-1 story:

Neu5Gc is what opened up this whole can of worms:

I wonder if alpha gal is playing a role in the improvements in arthritis and Crohn’s on plant-based diets: Dietary Treatment of Crohn’s Disease and Diet & Rheumatoid Arthritis.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

26 responses to “How a Tick Bite Can Lead to Food Allergies

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  1. Theanine supplements from green tea safe to take? Effective? Can someone please tell me Dr. Gr. feels this is harmful or harmless. Thank you so much. I hear good stuff about this green tea extract, but also concerns of its safety. Even minuscule amounts of caffeine I am intolerant to, so green tea drink out of question. Maybe decaf, but from what I have been told, one would have to drink a lot of decaf tea to get theanine benefits.

    1. I don’t know about thenine specifically as a supplement but Dr Greger addresses theanine in green tea in this video and notes that “the side effect of green tea consumption include things like less breast
      cancer risk, and living a significantly longer life. Additionally, drinking tea
      from the tea plant halves your risk of getting ovarian cancer. Halves
      your risk of getting endometrial cancer. Can lower our cholesterol, our
      blood sugars, and our weight. Protect our liver. And protect our brain and finally drink green tea every day.”

      1. Thanks. I know some people who avoid green tea due to aluminum and fluoride contents. Not sure if this is valid, but people swear by it, that green and black tea contain too much of this stuff.

        1. I also do not do well with drinking caffeine. For the past few months, I have been drinking a cup of hibiscus tea in the morning and really enjoy the taste. Dr Greger has has several videos on the subject and you might consider giving it a try. He said that hibiscus tea had the highest antioxidant content of the 282 beverages he tested last year. And did I mention that it is delicious!

    2. Hi Leslie. I would agree with siriusfarm’s comments and check out their provided links. Supplements are highly unregulated (I learned more about this when conducting our yeast testing.

      The only major supplements that most people need to consider are vitamin B12 and vitamin D. Here are Dr. Greger’s Optimal Nutrition Recommendations.

      We always try to encourage a “Whole Foods First” attitude, however, some folks may have certain conditions where additional supplements or herbal therapies can help. Of course, it’s best to discuss this type of information with your health care team, but I am happy to look into anything and give suggestive advice. For example, this study L-theanine, a natural constituent in tea, and its effect on mental state found “that L-theanine, at realistic dietary levels, has a significant effect on the general state of mental alertness or arousal.” Researchers did indicate more research is needed.

      Regarding safety it seems legitimate. Read more about L-theanine from Sloan Kettering

      Let me know if any of this helps?


      1. Joseph,

        Thanks for this. I will reach out to you with any revelations re: theanine if I end up trying it out. Also wondering how you and or Dr. G feels about milk thistle, as a tea or in powdered form of the ground up herb, ingested.

        1. Milk Thistle has many uses. Some research found it may help with ulcerative colitis. Study abstracts can be found here and here. It’s more commonly used for liver detoxification. The University of Maryland Medical Center has more basic information about it’s uses.

          I always take the stance that if a plant can help the symptoms of a disease, so long as it does not cause additional harm, there is no harm in trying.

  2. I have had the alpha-gal allergy for a few years now which makes me allergic to meat from any mammal. The reaction from most people when I explain it to them is they think it is the worst thing that could happen to someone. The allergy prompted my wife and I to explore plant based food and eventually become vegans. Based on how that has changed our health, I would say the tick bite that caused the allergy was more of a blessing than a curse.

  3. For factual accuracy, it should be noted that bacteria were first observed in the 1600’s, well before development of the electron microscope.

  4. Considering the large number of people with severe reactions to nuts/peanutes and mushrooms/molds/yeast and the various sensitivities to wheat/soy proteins – this is one of those cases where the claim that ” Our immune system is more likely to get confused between a chicken leg and our own legs than it is with a banana,” may require a lot more evidence to actually make sense …

  5. Nice blog, but a little off on the history. Van Leeuwenhoek observed and drew bacteria he saw through his microscope in 1676. Koch and Pasteur linked bacteria to disease in the mid-19th century. The first electron microscope was prototyped in 1931.

  6. My husband is a hunter and, consequently, he has had many tick bites over the years. For quite a long while (a year?) he has had problems with his digestive system. He has nausea, lack of appetite, weight loss, diarrhea, and stomach discomfort. He says the food that he chooses to eat is whatever he thinks sounds good or won’t cause him to gag. His diet consists of a banana and dry bagel every morning and then lunch and dinner is a lot of cheese, crackers, beef jerky, pizza, nuts, Snicker bars. One would think his stomach problems are from a poor choice of foods but he insists anything else (like a simple bowl of rice or pasta or some good plant foods containing fiber!) makes him want to vomit. The article “How a Tick Bite Can Lead to Food Allergies” has made me wonder if a tick bite might have caused food allergies that have led to food aversions for my husband. Are there any tests to determine such tick-bite-induced allergies or does one simply need the blood tests that check for Erlichia, Borellis, and Rickettsia (as his doctor suggested)?

    1. Since your husband is having digestive symptoms being evaluated by his physician is great. The tests you mention will help sort things out and if positive will help “rule in” a diagnosis. The problem is that a negative test may not “rule out” the problem. Tests have sensitivities and our immune systems has a long memory. It can react to perceived threats even with negative blood tests. However, many times our evaluations don’t identify a specific condition that is readily treatable. Given the complexity of the situation I often recommend to my patients a trial of dietary change. The one I am most familiar with is Dr. McDougall’s Diet for the Desperate. See his article by that name in his December 2002 newsletter available free on his website. As he mentions based on his experience many symptoms improve on a low fat plant diet with exercise. For those patients with continuing symptoms after that trial he often recommends his “diet for the desperate”. If you have been following you have a good understanding of how incredibly complex issues can be… and we continue to learn more all the time. Hopefully this information will help you and your husband working with his physicians to chart a path back to improved health.

  7. I find the theory that substances that are more similar to those in our own bodies will more likely cause all sorts of autoimmune responses, quite intuitive to understand. It explains why moderating one’s consumption of meat and dairy might not necessarily be enough to see any significant progress in some health issues such as arthritis, inflammatory bowel diseases and neurodegenerative conditions.
    It makes me wonder though: suppose someone, for some reason, just doesn’t want to give up eating meat completely. Would it be healthier for them to have a full-on meat-grill feast once in a month, than to have a small piece of meat every day, or even better than a ‘normal’ portion of meat once a week? Let’s assume they are not at the edge of having a stroke or heat-attack, so they won’t drop dead instantly by flooding their body with bad cholesterol and anti-bodies. Is it maybe better to be flooded with inflammatory substances once a month, than to have them flowing through your blood continuously by spreading out meat consumption over the entire month?

  8. .
    Dr Ed Masters found Lyme disease in his patients in Missouri many years ago. The CDC refused to allow him to call it LYME because birds don’t fly, deer don’t walk and ticks don’t crawl across state borders. The CDC even changed the lab test to eliminate the strain of BB that is found in Missouri. So those of us in Missouri are unable to get a diagnosis. So Ed Masters renamed Lyme disease after himself! Funny right? (see Pamela Weinstaub’s book, Cure Unknown for the whole story.)
    STARI is LYME!!!

    “The culprit, the lone star tick, so-called because females have a white spot on their back, are famous
    for causing Masters’ disease, a disease similar to Lyme syndrome, also
    known as STARI (southern tick associated rash illness). But thanks to
    the lone star tick steadily expanding its range (even as far as Long Island, NY), it’s not necessarily just so Southern any more.”
    My husband became allergic to pork in 1976 after receiving the Swine Flu Vaccine. He was sick for a long time before we figured out what had happened. It sounds crazy, but he is only allergic to pork that has been vaccinated, ie he is actually allergic to the vaccine! He is able to eat unvaccinated pork raised by my cousin and also that sold at a local farmers market. The owner of this pork farm chooses not to vaccinate her animals. Allergies are strange things

  9. This subject of allergies to foods goes way beyond just the tick bite. It’s a whole new subject; Mast Cell Activation Disorder

  10. Although the biology gets complicated it seems the answer to your question is “Yes.” Here is a link which should help with an explantion :
    Learn more about Alpha-Galactosidase

    “α-Galactosidase is an enzyme that catalyzes hydrolysis of the terminal α-galactosyl moieties of oligosaccharides and polysaccharides. These saccharides are abundant in plants, particularly in legumes and vegetables that make up important sources of food and feed. Human and most monogastric animals may not synthesize enough amounts of α-galactosidase in gastrointestinal tracts to fully digest these galacto-saccharides in their diets.”

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