At the turn of the 20th century, John Harvey Kellogg, MD, advanced the notion that most human disease is connected in some way to changes in the gastrointestinal tract. Kellogg and his brother, William, invented "corn flakes" and was the architect of the Kellogg cereal empire and the Battle Creek Sanitarium, a health spa in Michigan.1 His invention of cereals was driven by the belief that intestinal organisms, flora and fauna, could be positively or negatively influenced by diet. He favored a low-protein, vegetarian diet that emphasized high-fiber foods with laxative effects. He also advocated yogurt enemas to replace the good bacteria that might have been lost. Kellogg was obsessed with healing the gut that he believed was the key organ in understanding health and illness. While many of Kellogg's health beliefs and strategies were considered quackery, some of his quirky ideas about the health of the gut have become a dominant theme in translational research today.
In the September-October 2014 issue of Holistic Nursing Practice, a feature titled "Psychobiotics" addressed a growing focus on the gut-brain axis and the health significance of the millions of organisms populating the gastrointestinal track.2 A recent, quick search of Google Scholar on the term "gut-brain axis" yielded 118 000 hits in 0.05 seconds, confirming the continuing and deepening interest in the mechanisms by which the brain and microorganisms in the gut interact and how this interaction results in health or illness. In a review of research literature over the past 10 years, Mayer et al3 document that gut-brain axis mechanisms are implicated in the development of emotional behavior such as anxiety and depression and in the human response to stress and pain. The research methodology used to study these mechanisms often involves using "germ-free rodents" in "germ-free environments," that is, laboratory rodents bred with an absence of gut microbiota enabling the testing of certain experimental conditions in response to the absence of or the infusion of specific microbiota. Mayer et al encourage future research on the gut-brain axis' role in irritable bowel syndrome, autism, anxiety, depression, and Parkinson disease. Understanding the complexities of gut-brain mechanisms is a necessary precursor to further developing probiotic nutritional supplements or nutritional interventions to ameliorate disease conditions. Furthermore, nutritional assessment, including dietary habits and the use of supplements and probiotics, is crucial data in understanding the patient's health and illness patterns.
The critical focus on the health implications of the gut-brain axis is a holistic metaphor in that science finally has the tools to study crucial connections inside the body and how they respond to behavior and environmental conditions. I recently joined the listserv of the Web site, Microbiota for Health, at http://www.gutmicrobiotaforhealth.com/, where I follow gut-brain axis research developments that will surely improve health, wellness, and disease prevention.
-Gloria F. Donnelly, PhD, RN, FAAN, FCPP
Editor-in-Chief
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