Causes of Allergies

Symptoms of allergy depend on the form of allergy and allergen responsible for occurrence of allergy. Fatigue, headache, stuffy nose, tremor and collapse are some of the most common symptoms of allergy.

About 40% of us suffer from some form of allergies. And they're particularly bad during spring and fall, when pollens and molds are high. But allergies aren't just about a runny nose and scratchy throat. In fact, allergies are caused by a reaction in your immune system. When most people think of an allergy, they think of the sneezing, congestion, and itchy eyes caused by pollen. In fact, allergies can be caused by just about any substance that you inhale or swallow, or that touches your skin. You can also be allergic to shots. Your body's immune system is designed to attack harmful substances like bacteria and viruses. But with allergies, your body launches an assault far beyond what is called for on substances such as pollen, mold, dust mites, pet saliva and dander, and even medications and insect sting venom. Immunity is helpful protection against a substance. An allergy, meanwhile, is harmful hypersensitivity to that substance.

People with allergies have an inherited (genetic) predisposition for developing hypersensitivity to inhaled and ingested substances (allergens) that are harmless to other people. A healthy immune system is balanced between the activity of 2 types of white blood cells, called Th1 and Th2. Genetic or environmental factors can cause a Th2 dominated response to develop which can lead to allergies. The use of immunizations and antibiotic therapies and increased pollution leads to Th2 dominance. Once an imbalance in T cells develops, it tends to be continued by production of chemicals (cytokines) that keep the imbalance in place.

Risk factors for allergies include family or personal history of asthma, eczema, hay fever, or hives. The total environmental load of toxic substances (environmental pollutants, chemicals, etc.) that we are exposed to in our lifetimes reduces our immune function and leads to an increase in or aggravation of symptoms. Chronic ingestion of allergenic foods ("food allergies") weakens our immune function and leads to an increase in or aggravation or symptoms. Dietary sensitivities create a state of hypersensitivity and congestion of the mucus membranes. This congestion decreases the immune function of these tissues. Histamines, the naturally occurring chemicals that are involved in allergic reactions, are present in many foods as well as the pollens of trees, grasses, and weeds.

Intake of saturated fat (meat, dairy) and refined foods (sugar, white flour) enhance the inflammatory reaction, which is created by histamines. Chronic stress in any form is detrimental to the immune system. Forms of stress include mental/emotional stress, inadequate nutrition, chronic viral, bacterial, parasitic, or fugal infections, and repeated exposures to antigens in foods, chemicals, pollens, molds. Chronic stress decreases the Th1 response and increases the Th2 response. Not having been breast-fed may increase the risk of allergies.

The common prevalence of allergies suggests that more emphasis on prevention of allergies is needed for reducing their incidence.

Source : http://www.articlesfactory.com