Since the beginning of the 1960s, people with allergies have dramatically increased. The World Health Organization currently considers allergies a threat to public health. Researchers have tried to explain this significant increase. Professionals have proposed several hypotheses, including the Hygiene Hypothesis and “Old Friends” hypothesis.
Naturally, we wonder where allergies come from. Why do two people exposed to the same allergen have different reactions? Why are more children experiencing allergies than ever before?
In this article, we’ll explore why allergies develop and why they’re increasing.
Where Do Allergies Come From?
There are many forms of allergens that cause allergic reactions. These allergens can be airborne substances, foods, drugs, certain chemicals, or insect stings.
Our immune system protects us from illness by generating antibodies. In the case of allergies, the immune system generates Immunoglobulin E (IgE) when in contact with certain allergens. This reaction happens because the immune system sees the allergen as dangerous. Your body releases histamines in higher amounts, which leads to inflammation and other symptoms.
The IgE antibodies are custom-made and specific for a certain allergen. That’s why you may be allergic to one specific food or pollen but have no problems with other foods and substances. This condition usually develops early on in life and is common in children. In some cases, adults develop them later in life.
Genetics also plays a role as in where allergies come from. Researchers have identified certain genetic variations that run in families and cause allergies. If one parent has an allergy, there is a 30-50% chance that the child will also develop it. If both parents have allergies, the risk goes up to 60-80%.
The Hygiene Hypothesis
The hygiene hypothesis was first created by Strachan in the late 1980s. Strachan saw a correlation between family size or hygiene standards and an increased risk of allergies. Researchers noticed that the more siblings in a family, the lower the risk of allergies. The microbes in the environment help the immune system while protecting against allergies.
Today’s hygiene standards could also contribute to more people with allergies. With numerous sanitizing products that “kill 99% of germs,” we have less exposure to germs. Therefore, our immune systems become weaker and increase our risk of having an allergy.
The “Old Friends” Hypothesis
While many scientists support the Hygiene Hypthosesis, it doesn’t explain why allergies are still rising in unhygienic areas.
In 2003, researchers replaced the Hygiene Hypothesis with the “Old Friends” hypothesis. This theory focuses on ancient microorganisms, which have evolved alongside the immune system. These “old friends” support the development of the immune defense. Humans and these microbes depend on each other to function optimally. These microorganisms inhabit the skin, gastrointestinal and respiratory tracts. Some of the microbes are present in the soil, others in water, or the food we consume.
In 2008, Grammatikos expanded the “Old Friends” hypothesis. He added symbiotic bacteria and parasites to the list of microbes that offer benefits to the immune system. Genetic variations explain why some people respond differently to the same allergen.
These ancient microbes may affect more than just allergy development. The updated version of the hypotheses proposes a lack of exposure to them in early life may correlate with psychological stress and mental illness later in life.
Modern Life and Allergies
Today, there are more than 80,000 chemicals registered for use. But, many of these chemicals are not researched enough for safety. You can find synthetic materials in almost everything. From takeout contains to children’s toys to furniture and clothing.