What Accounts for the Prevalence of Food Allergy?

A recent paper in JAMA on the prevalence of food allergies in the US spawned headlines in opposing directions. Some media outlets emphasized that many fewer people have food allergies than believe they do, and thus implied that the problem has been exaggerated. Others noted that the numbers affected – nearly 11% of the surveyed sample of 40,000 adults intended to reflect the general population - were high just the same.

I side with the latter. An allergic reaction to food affecting more than one in ten of us is a substantial public health problem, not diminished in my view by the fact that almost twice as many thought they had food allergies. And quite frankly, they may be right. 

The study was limited to a short, stringent set of specific allergic responses- including such entries as hives, tongue swelling, trouble breathing, and vomiting. Food intolerance was not sufficient to make the cut; recurring symptoms associated with eating but not on their list would not make the cut. Even some specific, physician-diagnosed food allergies, notably oral allergy, were excluded. 

Of those reporting food allergies that did meet the researchers’ criteria, almost 40% reported at least one emergency department visit as a result. In part, that’s because the bar for defining a food allergy was set pretty high; a smaller percentage of those with food intolerances or less definitive allergy syndromes would ever wind up in the ER. But this is an alarmingly high number just the same. The math basics here are: roughly one in ten of us reports a food allergy potentially severe enough to warrant a trip to an emergency department, and of this group, four in ten wind up making such a trip. While food allergies can lead to severe reactions requiring emergency care, individuals with food intolerances generally experience less severe symptoms. This highlights the importance of understanding and managing food intolerance to prevent unnecessary emergency department visits.

I’m impressed. If we add intolerances to overt allergies- intolerances of lactose, lectins, gluten, FODMAPS, etc.- the numbers affected go up substantially. If we allow for the less discrete symptoms some food sensitivities induce- from bloating to brain fog- the numbers go up substantially. Add them all up, and this is a bona fide crisis of public health nutrition and modern epidemiology. Food is supposed to nourish and sustain us- not trigger the immune system like a bee sting or poison ivy.

Why is this problem so prevalent? There is no single, definitive answer- but there are some rather obvious and widely acknowledged explanations. They come in two basic flavors: what we are doing to our food, and what we are doing to ourselves.

Regarding food, we have altered it radically and cumulatively over recent decades. There is a reason Michael Pollan’s advice to eat “food” is cited so widely; it is a departure from the “stuff” so many of us are eating so much of the time. Food items with ingredient lists numbering into the dozens, and more, are not food- they are modern concoctions. That our immune systems would be prone to recognize such concoctions as foreign and potentially hazardous material is simply an indication that they are working as they should.

Concoction, though, is too vague an indictment. The specifics include the routine substitution of formula for the first, best, native food for Homo sapiens like other mammals: breast milk. They include food chemicals, such as artificial flavorants, artificial colorants, preservatives, miscellaneous additives (often as texturizers), sugar substitutes, and more. They also include trace, or maybe at times not so trace, amounts of herbicides, pesticides, hormones, and antibiotics. They include novel combinations of compounds that don’t occur in nature; sometimes it is compounds in combination rather than in isolation that trigger the immune system to strike back. They include genetically modified food products as well. While genetic modification can be useful and safe, it is nonetheless subject to the law of unintended consequences. If novel proteins, for instance, are introduced into foods- new allergies and intolerances are likely to result.

Regarding ourselves, our various immune reactions to food relate to both the health and balance of our immune responses in general, and the integrity of gastrointestinal lining. The former is very much in question in the context of modern living, which is “inflammatory” in a variety of ways. Stress and sleep deprivation are generally inflammatory. Importantly, modern diets tend to be inflammatory due to excesses of saturated fat, refined carbohydrate, added sugar, and perhaps to a lesser extent, omega-6 fats, along with relative deficiencies of omega-3 fats, fiber, and diverse antioxidants from plant foods. This creates an obvious feedback loop: inflammatory modern diets heighten immune system responses, including to compounds delivered by that very diet.

Disturbances directly affecting the gastrointestinal lining may be of even greater concern. Here, too, there is potential for a feedback loop: inflammation of the gastrointestinal tract resulting from various sensitivities can cause so-called “leaky gut” which increases the likelihood of heightened immune responses to compounds in food. Perhaps more obviously, modern living and the modern diet are known to damage the microbiome, which is a key contributor to our healthy digestion. When sensitivity to a compound like gluten becomes more prevalent over time, it likely has less to do with gluten- which has been part of the human diet for 15,000 years at least, and perhaps 150,000- and more to do with the state of modern guts, to put it bluntly.

How can you tell if you are among the many millions affected by some form of food sensitivity? There are many approaches to testing, and in some cases- such as celiac disease- blood work can be diagnostic. Generally, though, the most reliable approach is the n-of-1 experiment called an elimination diet: suspect foods are taken away to see what happens to symptoms. Suspect foods are added back, and ditto. This can be done any number of times, and with any number of suspect foods, to get to something close to certainty. Generally, though, if the association is strong- there is a clear change in how you feel directly linked to certain elements in your diet- it’s a fairly efficient and quite decisive method. Health and nutritional professionals can guide you through it; if yours can’t, ask to be referred to one who can.

Finally, what can we do about this- individually, and collectively? As individuals, if food allergy or sensitivity is already established, our best option tends to be the obvious one: steer clear of those food sources. Sometimes, however, desensitization may be possible (a physician expert in allergy will be needed here), and sometimes we can alter the sensitivity with an improvement in gut integrity, achieved by improving health and diet overall, by eating less processed foods, by reducing inflammation in our bodies, and by supporting a healthy microbiome- at times with a probiotic. As a personal anecdote, and nothing more, I developed a sensitivity as an adult to some nuts I like to eat routinely; it went away with the addition of a daily probiotic to my personal routine.  (I note, for completeness, a recent studythat raises questions about the effects of using probiotics immediately after antibiotics. I have favored this approach historically, but this new study raises some doubts. I will look for more research in this area and adjust my views accordingly; I encourage you to do the same. That’s how science works!)

The above strategies are even better for prevention. A clean diet of wholesome, minimally processed, mostly plant foods will provide far less provocation to the immune system, and will help to support both a balanced inflammatory response, and healthy gut integrity. It will tend to support a balanced and robust microbiome as well. Attention to physical activity, sleep, emotional well-being and stress, and toxic substances such as tobacco and excess alcohol- the customary priorities of lifestyle medicine- also figures importantly in gut-mediated immune responses. There is a reason we speak routinely about feeling things “in our gut;” having “butterflies in our stomach;” and having “visceral reactions.” Connections between gut and mind, between gut health and overall health, are diverse and powerful.

Rates of food sensitivities- severe allergies, mild allergies, autoimmune conditions, intolerances- are very high. Generally, the only safe approach to an established, severe allergy is avoidance. But viewing the problem more generally, the triggering faults lie within our modern food supply, and within our bodies. We have means at our disposal to ameliorate both.