Decoding The Mystery Of Rising Food Allergies Globally

Introduction

Food allergies are a growing health problem that affects millions of people around the world. They can cause a range of symptoms, from mild to severe, and can even be life-threatening in some cases. 

We moved from India to the US in 2021. Here in the US, nearly everyone I met has allergies to one or more food ingredients. Some are allergic to peanuts; some are allergic to fish. Kids and adults here carry EpiPen to help them survive in case they face a severe allergic reaction. 

Back in India, when I was a kid, food allergy was pretty uncommon. But times are changing. Food allergies are not seen only in the US. It has slowly become a global phenomenon.

In this article, I will discuss in detail the genesis of food allergy and how it has come to become a globally prevalent epidemic.

(The references in this post are numbered and those numbers are hyper-linked. Do click on those to verify the arguments made!)

What are Food Allergies and How Common are They?

Food allergies are a type of disease that occurs when the immune system mistakenly identifies a certain food or a substance in food as harmful and starts fighting against them. This unnecessary fight causes collateral damage to the body tissues. Depending on how forcefully the immune system reacts, patients may suffer from symptoms ranging from itching, swelling, hives, abdominal pain, nausea, vomiting, difficulty breathing, low blood pressure, loss of consciousness and even death.

Food allergies affect nearly 10% of the general population. (1) (2) And this is rising. Epidemiological data from various parts of the world show that the prevalence of food allergies just doubled in the past 10 years. (1)

When I read this research on how the prevalence of food allergy is rising, like you, I too asked myself- “what has changed in the last 10 years?”. Is the air that we breathe in more polluted now? Are we eating more processed food now than 10 years ago? 

While these do form part of the answer, the true answer that I discovered will really surprise you.

The most common foods that cause allergic reactions are milk, eggs, peanuts, soybeans, wheat, fish, shellfish, sesame seeds, and tree nuts. However, one can potentially develop an allergy to any food. 

Food allergies are more common in children than in adults. But many children grow out of such allergies. (3)

In adults, it is extremely difficult to lose allergies once developed. As we delve deep into why food allergies happen, you will understand the reason. In the US, food allergies tend to be more common amongst the Afro-American population compared to non- Hispanic Whites. (1) As you read this article, you will discover why. Another interesting observation is the fact that food allergies are common in families with higher educational level. (4) And there is a fascinating reason behind this intriguing association between education and food allergy.

What Causes Food Allergies?

Biologically we are always at war. There are millions of dangerous organisms and chemicals around us- in the air we breathe, in the water we drink and in the food we eat- that can kill us unless they are properly dealt with and neutralized. To provide this protection our immune system must differentiate between what is “self” and what is “foreign”. However, it is also true that not everything that is “foreign” is harmful. In most cases our immune system is mature enough NOT to act against everything that is foreign. It is mature enough to determine when to attack and when to simply ignore.

For example, the foods that we eat are all “not self”. Food particles are all “foreign” in nature. But, when our immune system is mature, it doesn’t attack whatever we eat just because it is foreign. Our immune system always waits and checks if the foreign substance is causing any harm. 

Similarly, a lot of inert harmless particles like dust etc. enter our system when we breathe. And because these particles are harmless, a mature immune system simply ignores the fact that these are “foreign” particles and doesn’t start attacking.

Our immune system also has a great memory. So, if it determines that a foreign particle is not causing any harm, it will remember that. It will remember not to attack that specific foreign particle. So is true regarding any foreign particle that is associated with harm. If a foreign substance causes any injury, our immune system will store this information in its memory. So, the next time when it encounters this “harmful” foreign substance, it will not wait. It will simply attack.

Now, if the immune system is immature and sensitive, it won’t have the patience to observe if the foreign substance is harmful. Such an immature immune system might end up attacking certain food substances just because it wrongly thinks that those food substances are harmful. And this attack is experienced as food allergy. 

Similarly when an immature immune system wrongly identifies dust particles or pollen grains in the air as harmful, it leads to allergic conditions such as asthma. No wonder, patients who suffer from allergic asthma have extremely high chances of developing food allergies. Similarly, patients with food allergies are the ones with a very high likelihood of developing allergic asthma. (3)

So, the question is- what makes the immune system of some patients’ immature and sensitive?

Food Allergies in Children

As we discussed, our immune system will attack any “foreign” particle that is associated with “injury” or “harm”. At this point, just note that any form of injury generates a set of signals which are collectively known as inflammation. So, any injury leads to inflammation. 

Most childhood food allergies are acquired in the first or second year of life and then fall progressively until late childhood. Cow milk allergy is the most common food allergy among infants and young children. (3)

In the case of young children, all biological systems are still developing. Processing “tough” foreign particles can sometimes be a challenge and in that process sometimes small injuries can happen. This is especially true while processing protein particles in food. Biologically, proteins are a bit difficult to digest and process. So, when an infant drinks cow’s milk, digesting lactose sometimes can lead to “micro-injuries” in the gut. The resultant inflammation tells the infant’s immune system to remember “lactose” as a harmful foreign substance. So, next time that kid drinks cow’s milk, the kid’s immune system starts attacking lactose in the milk. This attack is what manifests as cow milk allergy.

Now, so long as that kid avoids drinking cow’s milk no allergic manifestations are seen. But we forget the fact that the kid is growing. And with growth the ability of the gut to digest lactose will improve with time. Eventually, there won’t be any “micro-injuries” while digesting lactose. But, if the kid keeps avoiding cow’s milk, the immune system will always remember that lactose is harmful. However, if this kid starts taking cow’s milk in small amounts regularly, eventually the kid’s immune system will note that lactose is not causing any harm and will learn to tolerate lactose.

Whatever we discussed above is true for nuts and other food substances that contain “tough” proteins. That’s why, many children who are sensitive to a particular food often  start tolerating the same food as they grow up. 

Food Allergies in Adults

In the case of adults, the story is a bit complicated. As we grow older, we keep encountering so many different pathogens that cause injury and inflammation. Each chemical process that takes place in our body always causes some form of injury and inflammation. As a result, the older we are, the more are the chemicals of inflammation in our body. They keep signaling our immune system to be in an “attack” mode. They make our immune system more sensitive. Such a sensitive immune system is often immature and tends to panic. 

Now imagine an immune system that is continuously receiving inflammation signals. These signals keep telling the immune system that some injury is ongoing. Now, in such a state, if it encounters a foreign substance- let’s say shellfish protein- it is prone to associate shellfish protein with injury. It will start attacking shellfish protein leading to shellfish allergy. 

So long as this adult keeps avoiding shellfish, he will be ok. But his immune system will always remember in future to attack shellfish protein the moment it encounters the same. Of course, it is possible to retrain this immune system by taking small amounts of shellfish regularly and make it identify shellfish as “harmless”. But the high degree of inflammation signals in adulthood makes such “desensitization” difficult and sometimes dangerous. Adults react more vigorously and dangerously than kids to substances they are allergic to. (5) (6)

Why Is Food Allergy Becoming More And More Common?

The prevalence of food allergies in children (aged 0 to 17 years) has slowly increased in the USA, from 3.4% in 1997 to 1999 to 5.1% in 2009 to 2011. (3)

Data from two Chinese regional cross-sectional food allergy prevalence surveys administered in 1999 and 2009 indicated that food allergy prevalence approximately doubled over a ten-year period from 3.3% to 7.7%. (1)

The underlying principle is that if there is a high level of inflammation in the body, the immune system will always think there is a great deal of ongoing injury. In such a state, any foreign substance present in the body can be erroneously labeled as one of the causes of ongoing injury, especially if it is a bit tough to process that foreign substance. 

All living organisms we see in this world are products of millions of years of evolution. Evolution allows us to adapt optimally to our surroundings such that we harmoniously fit in that environment. The downside to this is that any other environmental parameters might not be optimal for our biology.

When I say environment, that includes the climatic conditions, the available food in that environment and all other environmental parameters.

For example, I am a Bengali and I hail from the eastern part of India near Bay of Bengal. My ancestors, for thousands of years, lived in a hot and humid climate and ate mostly fish and rice. So, my evolution has molded my body to live optimally in a hot and humid climate. My evolution allows me to digest fish and rice optimally. Bread, beef etc. is not natural to my evolution. Extreme cold is not natural to my evolution.

To imagine this in a simple way, imagine that evolution keeps a memory of what our ancestors did and ate. Evolution has a memory of the situations and conditions our ancestors faced. So long as the current food or environmental conditions somewhat match this evolutionary memory, our body is relaxed. But anything drastically different will make our body feel threatened. It will get stressed. I will react.

I keep giving this analogy whenever I have to explain a layman- if my body like a paper shredder, then so long as it gets paper it’s ok. But if metal plates are thrown in, the same paper shredder will start getting burnt out and eventually fall apart.

Imagine the stress my entire biology will face if I, who has a Bengali ancestry, consume bread, and beef every day and live in a cold climate!

Over the years the environment and climatic conditions around us do change. But so long as those changes happen slowly over centuries, we usually adapt to such changes via the process of natural evolution.

But, in the last few decades we have embraced globalization and industrialization. This globalization ensured a rapid and drastic change in our food habits and in our environment. Today, we can access food from different regions and cultures with ease. We can eat a Chinese breakfast, a Danish lunch, and a Mexican dinner on the same day. People frequently migrate from extremely hot and humid climates to freezing cold and dry countries in just over a few hours and even settle there.

These changes are too dramatic and too rapid. What would generally take thousands of years, now simply takes a few weeks. Natural evolution can’t catch up with this pace of change. But our body is still a product of this painstakingly slow process of evolution. So, what it faces and eats is not even close to the evolutionary memory. 

As a consequence, our body’s biochemical machinery gets burnt out trying to process food and climatic conditions that it was not designed to process. This burn-out results in a constant ongoing injury at cellular level, leading to a state of chronic inflammation. And in this state, it is sensitive and panicky. And when it faces dense proteins which are anyways a bit difficult to process- it tends to recognize these proteins as the cause of injury.

And this is how food allergies begin! And this is the main reason why food allergies are spreading like pandemic. And it will keep rising and spreading as we become more and more globalized.

The relationship between stress and food allergy gets highlighted in a particular type of food allergy called “food-dependent, exercise-induced anaphylaxis”. This is a form of food allergy in which the patient only develops symptoms when ingestion of the culprit food is followed within a few hours by exertion or exercise. Symptoms do not develop if the food is eaten at rest or if the patient exercises without first eating the food. (3) The stress from exercise makes such a patient’s body react to certain food substances. 

Whatever I explained is not just a theory. There are several published studies which confirm this phenomenon. 

For example, in the US, allergies are more common amongst Afro-Americans. (1) (2) And the reason is simple. Afro-Americans are not native to the US. They hail from the hot plains of Africa. Due to similar reasons, in the US, white adults have lower rates of food allergy relative to their Hispanic, Asian, and multiracial counterparts. Also, these “non-whites” report higher rates of severe reactions compared to the white Americans. (1)

The US itself is a hot-bed of food allergies. Because the native white Americans themselves are not originally from this land.

A famous Australian study on food allergy called “HealthNuts Study” showed that peanut allergy was roughly three times as prevalent among Australian infants whose parents were born in East Asia relative to infants with Australian-born parents. (1)

Summary

I hope you are convinced by now that food allergy is a direct result of the pace at which we are getting globalized. We are not biologically designed to handle the rapid changes brought about by globalization. Our biology cannot evolve so fast. And this mismatch between our biological evolution and globalization makes our immune system sensitive and panicky. And this is the main reason why we see rising incidence of food allergies globally. This evolutionary mismatch also results in complications ranging from diseases such as diabetes, hypertension, heart attacks, stroke etc. I have discussed this in detail in another post, which you can read by clicking HERE.

Can we prevent food allergies? Can we treat food allergies?

This is exactly what I will discuss in the next post. Do watch out for that post!