Allergy, intolerance, sensitivity
How undesirable food reactions occur
The exact number of people suffering from food allergies is difficult to estimate: according to various estimates, it is from 1 to 5 percent. However, scientists believe that we face food anaphylaxis more and more often — both in childhood and throughout life. In the book "Allergy, Intolerance, Sensitivity" (Mann, Ivanov and Ferber publishing house), translated into Russian by Evgeny Ponikarov, Ruchi Gupta, MD, tells how food allergies arise, what successes modern medicine has achieved in combating them, and also how allergies differ from intolerance and sensitivity. We invite you to familiarize yourself with the fragment devoted to how the modern lifestyle makes us vulnerable to allergens from the environment.
How Your Microbe Friends Help Immunity
Sanitation and cleanliness have significantly improved our health over the past hundred years, and regular hand washing and daily showers play a big role here (especially during critical periods, as with the COVID-19 pandemic). However, we may have to pay the price for focusing too much on cleanliness. Few people at an early stage of life (and throughout it) face potential enemies of the immune system, which challenge it and significantly strengthen it. Few of us live on farms, regularly come into contact with animals, as it was with previous generations, and even play outdoors. The modern lifestyle binds to a "non-microbial" room and does not allow you to communicate with nature. Methods that help train and strengthen our immune system are disappearing, as a result reducing sensitivity to allergens from the environment. And when we come out of our sealed buildings, it often happens in artificial conditions with minimal biodiversity. For example, we spend time at concrete stadiums and sports grounds planted with non-native grass or having artificial turf.
In 1989, British epidemiologist David Strachan put forward a hygienic hypothesis: exposure to infections in childhood will provide protection from allergies in the future. He suggested that the decrease in the number of infections in childhood is the reason for the surge in allergic diseases in the XX century. Strachan published the results of his research in the British Medical Journal: in children in large families, pollinosis is less common, since germs are transmitted from older brothers and sisters. This prompted further research, which confirmed that if an artificially clean environment was around the child in early childhood, his susceptibility to diseases may increase. Although this idea is simple in itself, it has contributed to the theory that an increase in the number of chronic allergic diseases may be an inevitable price to pay for getting rid of the burden of deadly infectious diseases.
As an example, I'll show you what happens when building muscle and strength with the help of exercises with weights. To lift heavy objects, you have to pump your muscles, gradually increasing the mass of the objects being lifted. Without proper training, you will not be able to lift weights "to order". The same is true for the immune system. To fight infection (a kind of burden), the immune system needs to be trained, it must fend off pollutants available in everyday life. If the system is not affected by pollutants, it will experience difficulties in fighting severe infections.
This conversation would be incomplete without discussing the relationship between our immune system and our microbiome — the totality of all microorganisms living on the surface of the body and inside it. Many of these microorganisms support our health and establish beneficial and mutually beneficial alliances with the body. The microbiome is, if you will, a biological connecting link that connects your interaction with the environment (and potential allergens) and the immune system.
The word microbiome comes from the Greek words μικρός ("small") and βίος ("life"). This is the name of a community of microorganisms that inhabits a certain environment (in our case, the human body). When I started studying immunology and microbiology in college, no one could tell what a microbiome was. Today, its decoding — from the community inside the body to the colonies inhabiting the skin - is one of the most promising areas of science. We are at the very beginning of an exciting journey towards understanding and harnessing the possibilities of the human microbiome.
The ecosystem that makes up the human biome includes a diverse set of microorganisms: bacteria, fungi, yeast, parasites and viruses. Their total genetic material far exceeds our own DNA. The initial settlement of microbes occurs when the child descends through the birth canal and is exposed to the organisms living there (although some microbes enter the fetus while it is still in the womb of the mother). Microbes envelop us, creating a thriving microbiome, and this process continues as we begin our life in the outside world. By the way, this explains the difference in the health of children born naturally and children born as a result of a relatively sterile caesarean section. In children born by caesarean section, the correct microbiome may not develop, and as a result, the risk of certain diseases increases later in life, mainly inflammatory, metabolic and immune problems (including asthma and food allergies). However, it has not yet been decided how to compensate for the lack of "microbial baptism" during cesarean section in order to protect the child and help the proper development of the microbiome. The method of birth is not the only factor affecting the risk of developing diseases and the formation of the microbiome. Other reasons include the health and age of the mother, the presence of breastfeeding, exposure to the environment at an early age and eating habits.
Is it my fault here?
When a woman gives birth to a child with severe food allergies (for the sake of such a case, we add eczema and asthma to the mixture), she often wonders if this is her fault. Maybe it's the diet during pregnancy? Some kind of external influence? An unscheduled caesarean section? Absolutely not!
Let's face it: the best research and most modern works agree that the rejection of certain foods during pregnancy and/or breastfeeding is ineffective for preventing allergic diseases. A 2012 systematic review, which included five randomized trials and over nine hundred patient histories, came to the same conclusion. Not all expectant mothers understand this. The 2018 study analyzed data on almost five thousand pregnant women. It turned out that about 3 percent of expectant mothers reduced their consumption of nuts, eggs and dairy products in the hope of preventing food allergies in newborns.
Nevertheless, there are reasons to continue discussing the caesarean section factor. In 2016, a group of Greek specialists found a link between caesarean section and food allergies in 459 children who were examined at certain intervals during the first three years of life. Those who were born by Caesarean section and who had at least one parent with food allergies were more likely to show their own allergies than children born naturally from non-allergic parents. However, it is unclear which factor influenced more — the method of delivery or hereditary allergy. Among the two and a half thousand German babies born by Caesarean section, food allergies were also more common. In a Swedish experiment, over a million babies born from 2001 to 2012 were examined and found that children after cesarean section had a 21 percent higher risk of developing food allergies than those born naturally.
This does not mean that this method of delivery should be avoided or that a caesarean section condemns the baby to future health problems. The development of food allergies (and any other health problems) is facilitated by a lot of other factors that arise much later, for example: the use of antibiotics, environmental exposure, the introduction of foods into the diet at an early age, and so on. In many cases, a caesarean section is medically necessary.
When I gave an interview to a national newspaper, I was asked as a specialist about research on the early introduction of peanuts into the diet. Then they asked a question about my daughter and what I was doing. As a result, the article said something like: "Dr. Gupta scolds himself for not giving her daughter peanuts at an early age." I repeat: it is not necessary to look for the culprits. We all try to act as best we can according to our knowledge at the moment. Don't feel guilty about the cesarean section. Forget about it and do your best.
Intestinal bacteria are especially important. They have a say in everything that concerns us — from the efficiency and speed of metabolism to the risk of all kinds of diseases, including allergic ones. They help digestion and assimilation of nutrients. They also produce and secrete important enzymes and other substances that the body needs and that it itself cannot produce in the right quantities. These are vitamins (especially B vitamins) and neurotransmitters (for example, dopamine and serotonin). It is estimated that about 90 percent of serotonin (the hormone of good mood) is produced not in the brain at all, but in the digestive tract thanks to local microbes. The intestinal microflora, as it is sometimes called, and its effect on your hormonal system help to cope with stress and even get a good night's sleep. The above is just the basics on the topic (you can write whole books about intestinal bacteria, and many have already written). We will continue to talk about the relationship between microbes and the immune system and the likelihood of whether we will suffer from food allergies.
Read more:
Gupta, Ruchi. Allergy, intolerance, sensitivity. How undesirable food reactions occur and how to prevent them / Ruchi Gupta, Kristin Loberg; translated from English. Evgeniya Ponikarova; scientific editor M. Tchaikovsky. — Moscow: Mann, Ivanov and Ferber, 2022. — 416 p. — (Secrets of health).
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