Month after month, scientific articles provide proof of the relationship between health and a healthy lifestyle. Cola may up osteoporosis risk for older women; Berries and curry are at frontiers of diet-brain research; Mediterranean diet shows promise in preventing Alzheimer disease; Increasingly, scientists are discovering the same healthy habits that benefit your heart and waistline... are a few headlines from recent issues of The Tufts University Newsletter, Prevention magazine and other health publications.
At the bottom of this relationship between lifestyle and health we find the immune system, whose function is stimulated or depressed by physical activity, the food we choose to eat and the toxic substances we put into our system.
Fifty years ago, we still knew very little about the immune system. In those days, only a handful of illnesses were classified as autoimmune, conditions where the immune system doesn't recognize proteins normally present in the body and attacks its own cells. Today, researchers have found that autoimmune responses explain about 10 percent of the diseases that affect the population; among them, diabetes (type I), lupus, multiple sclerosis and rheumatoid arthritis, to name only the most common ones. Ulcerative colitis and even schizophrenia are suspected to have a link to autoimmune responses. Furthermore, conditions such as coronary disease have been related to the efficiency of the immune system in clearing up plaque deposits in the heart's arteries.
By the end of the 19th century, vaccines were invented; Louis Pasteur discovered germs as the cause of many illnesses, and, later, body reactions to specific microorganisms, like the tuberculosis Koch's bacillus were identified, confirming the existence within the body of the immune system. From that time on, the immune system was conceptualized primarily as a defense army in charge of destroying an enemy, reflecting the predominant martial mentality.
Koch and Pasteur inaugurated an era where all illnesses started to be explained in terms of germs. In the early 1940's, viruses were found capable of generating illness, and the '60's and '70's saw a great boom in virology, when researchers tried to establish a causal relationship between virus and cancer. A co-relationship (not a direct causal effect) has not been confirmed, except in a few cases, such as Papilloma Virus and cervical cancer in women.
The above-mentioned research efforts were not in vain, and as the result of those studies, science has learned a great deal. Researchers have established that human bodies continuously produce cancer cells, that the immune system is capable of recognizing misbehaving cells, and of isolating, reeducating and/or destroying them, depending on the circumstances. A clear relationship between cancer and the immune system has been established. When the immune system is depressed, cancerous cell growth is not controlled.
Since the beginning of the AIDS epidemic in the early 80s, investigators have plunged into studying what exhausts the immune system in these patients, contributing very interesting insights into its multiple functions.
Our Second Brain
Beyond an army that chases, confronts and destroys invaders, the immune system is presently conceptualized as a self-governing network that participates in the body's learning process, and is responsible for both its molecular identity and the biochemical communication between organs. That's why author Fritjov Capra deems it our second brain.
Different from other body systems, which are confined to a precise anatomic location, the immune network penetrates each tissue of the body. It is made of a number of tissues and organs (lymphatic organs), specialized cells (lymphocytes and macrophages or white blood cells) that swim back and forth along the circulatory system during surveillance missions, gathering data to assure the organism's accurate functioning.
This extraordinary system learns and evolves with experience! From the moment we are born, it learns to discriminate which molecular features typify bacteria that are usually not present in mammals. It also recognizes which are the body's idiosyncratic proteins. Vaccines are developed based on the immune system's capacity to memorize how to react to alien proteins. Many immune system organs function as gatekeepers. This is the case of the lymph nodes (in the neck, armpit and groin), the tonsils and the Peyer's patches in the intestine. The lymphatic fluid, or lymph, goes through these "customs" points where lymphocytes detain particulate matter and microorganisms and decide if they should be granted admission to the system or not. Another lymphatic organ, the spleen, is in charge of recycling old and dysfunctional cells.
This amazing system only uses its defensive resources when facing a massive invasion of foreign agents.
Moreover, the borders that science had delineated between systems start to blur, bringing opportunities for new understandings of the body's functioning. Recent research shows that brain, endocrine glands and immune system cooperate and share functions. The brain produces neuropeptides that are antibacterial precursors; the immune system has perceptual functions, and the endocrine system produces substances that work as neurotransmitters. Initially deemed as exclusive to the nervous system, they have also been found in the bone marrow, where the immune system cells are produced.
The three systems are thus, multifunctional. They form a network that exchanges, stores and passes on information, using peptide molecules as messengers. But, also, our physiology is modulated by emotions. Popular wisdom, which results from observations transmitted from generation to generation, has always correlated emotional stress with vulnerability to illness, and science has proven that our thoughts, mood and emotions influence the functioning of the nervous, endocrine and immune system and vice-versa.
Science is telling us that we can regulate the production and efficiency of our messengers (peptides) by adopting healthy lifestyles. So, eat healthy, have fun, step up!
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