In fact, this is an ambitious question for which no “precise and comprehensive” answer has yet been reached. Allergies have been studied for decades and theories have emerged, but rigorous scientists believe that the information available is still only a “few pieces of the puzzle” and not enough to decipher the full picture of allergies. Nevertheless, there is one theory that is widely shared by researchers – the “hygiene hypothesis” – which states that the better the hygiene conditions, the fewer infections children have early in life and the more likely they are to develop allergies later in life. This seems to explain why the more developed and clean a society is, the more likely people are to have allergies. 1. Just because it is too clean? The British Broadcasting Corporation (BBC) recently followed up with two families of allergic children in the UK to try to prove the “hygiene hypothesis” through the form of a documentary. The first family is a family of four, 8-year-old boy Joe and his parents and sister live together, he suffers from severe asthma, hay fever, eczema, but also to some nuts, pets and dust allergies. The other family has a young patient named Morgan, who is 4 years old and suffers from allergies. In addition to suffering from severe eczema and hay fever, he could not eat any nuts, dairy products, soy, kiwi, avocados, bananas, and was also allergic to rubber, cats, dogs and horses. Both families provided the study with bacterial smears of the skin and intestines of all family members as well as of their respective residences. The results showed that both families carried “too few” types of bacteria, both in their living environment and on their members. The researchers said that the human body is covered from head to toe, inside and out by a variety of bacteria, as many as ten times the total number of cells in the human body. These bacteria help boost the body’s immune system. For example, the earlier children are fully exposed to the stimulation of microorganisms such as endotoxins, the easier it is to produce antibodies and the less likely they are to develop allergic diseases later in life. However, in developed Western countries, with changing lifestyles and improved hygiene, most families are unable to “cultivate” an abundance of flora, making it difficult to induce primitive immune function in children’s bodies. This is the case with Joe and Morgan’s family, whose daily activities were followed by the BBC, which found that they spent an average of 91 percent of their day indoors, with little exposure to outdoor air, garden soil, or small animals. In contrast, in some developing countries, especially those that still retain traditional hunting practices in primitive areas, scientists found that the local population carries a variety of flora, only one in 1,500 people suffer from allergies. In the UK, on the other hand, one in three people are allergy sufferers. “According to the World Allergy Organization, the number of people suffering from allergic asthma has increased at an alarming rate over the past 40 years, averaging 50 percent per decade. In the United States alone, the number of allergic asthma patients is 20 million, and food allergy patients are 12 million, accounting for 4 percent of the total U.S. population. 2. Why more children? In recent years, children with allergies like Joe and Morgan have become increasingly common in Western countries. Statistics from major medical research institutions in the United States show that the number of American children with food allergies has increased by about 20 percent in the past 10 years, with peanut allergy alone doubling the number of children with allergies. Parents are also quite confused about this. Some parents’ first reaction to their child’s peanut allergy is usually, “Nobody was allergic to peanut butter when we were kids.” The medical community is also very concerned about the phenomenon of children’s susceptibility to allergies in Western developed countries, and has conducted many related studies in recent years, trying to explore the causes from different angles. Researchers in the United States found in 2013 that children born by cesarean section were at higher risk of developing allergies than children born by normal delivery. The researchers evaluated more than 1,200 newborns at 1 month, 6 months, 1 year and 2 years of age and found that by age 2, the rate of allergies in children born by cesarean section was five times higher than in children born by normal delivery if they were exposed to pet dander, mites and other common allergens in the home. Study leader Cole, chairman of the Department of Health Sciences at Henry Ford Hospital in Detroit? Johnson said that early exposure to microbial environments has an impact on children’s immune system development and allergy attacks, while maternal bacteria that children are exposed to during a normal birth may have a beneficial effect on their immune systems. Johnson believes that when exposed to allergens, children born by cesarean section are more likely to produce immunoglobulin E, which has been linked to the development of allergies and asthma. A Norwegian study yielded similar results. According to the researchers, the proportion of children born by cesarean section is much higher in developed countries than it was 20 years ago, which may explain why children today are more “sensitive” than their parents. In addition, a study conducted by the University of Nottingham in conjunction with several medical schools has pointed out that the widespread use of antibiotic drugs may also be responsible for the high incidence of allergies in children. The study found that early antibiotic use may lead to a 40 percent increased risk of eczema in children. Dietary habits and preferences can also affect children’s chances of developing allergies. A study in the Journal of the National Academy of Sciences compared the daily food and intestinal flora of 15 children in Florence, Italy, and a small village in the African country of Burkina Faso. The results showed that the Italian children’s daily diet was rich in sugar and animal fats and high in calories, while the African children were mainly vegetarian; the intestinal flora of the children in the two places was therefore very different, with the African children having a much higher diversity of bacteria than the European children. In this regard, Paolo Lignetti, a pediatric medicine expert from the University of Florence, Italy, said that the intestinal flora of children in Western countries is different. Lignetti said that hygiene measures and virus vaccines in Western countries may have been effective in controlling many infectious diseases, but they have also reduced children’s resistance to many allergens. In contrast, “in a place like Africa, you may die from a disease infection, but you are hardly allergic, not overly obese, not suffering from asthma or enteritis.” 3. proximity to nature: Despite so much research focusing on allergies, scientists are not yet able to fully and accurately answer why more and more people are allergic. Experts believe that the environment in which humans live is changing and the body itself is evolving, and that allergies are precisely the stress response of the body’s immune system to these changes. Each research finding that humans have today is like adding a piece to the puzzle, and in the future not only will they be able to put together a complete theory about allergies, but they will also be able to provide effective measures to prevent and treat them in practice. Over the years, research on allergy prevention has never stopped, and one theory that has gained widespread acceptance is the one proposed by Erica von Mutius, a senior expert in allergy research. One theory that has gained widespread acceptance is the “farm effect” proposed by Erica von Mutius, a veteran of allergy research. A pediatrician in her early years, Von Mutius is now a professorial specialist at the University Children’s Hospital in Munich, Germany, and has devoted decades to allergy research. Years ago, she learned from a Swiss country doctor that children living on traditional European farms never suffer from hay fever or hay fever. This observation by the country doctor initially raised questions from people like von Mutius. In 1998, Von Mutius, together with experts from Germany, Austria, Switzerland and other European countries, began a large-scale study of traditional farms in Europe. The study, which took several years and gradually grew to 14 participating countries, has become one of the pillars of European medical research on allergies today. Von Mutius found that farm children were allergy-free because they and their families maintained a traditional farm routine: working in the fields, milking the cows, cleaning the stables, and so on. She further summarized the “farm effect” into three key elements: exposure to livestock (especially cows, dogs, ducks and other poultry), exposure to forage, and drinking fresh milk “Humans have been dealing with farm animals for thousands of years, so there may be some evolutionary mechanism that allows the human immune system to function properly,” she said. The immune system works properly,” said von Mutius.