Small Intestine - Female Organs - Human Anatomy

Gut bacteria make up each individual’s microbiota and humans likely wouldn’t survive more than a couple of years after birth without bacteria. 1 Gut bacterium begins being populated as a baby enters the world through the birth canal and gains beneficial bacteria from the mother. There are approximately 1,000 different species of bacteria in the Gastrointestinal (GI) tract and up to 1015 total bacteria in the lower intestine.

However, dysbiosis, “altered pathogenic bacteria in the gut”1, can occur for a variety of reasons – some of which are believed to be food poisoning, poor diet, physical and psychological stress, altered gastrointestinal tract and antibiotic use. 2 An individual’s health can be affected when gut bacteria is compromised, disturbing learning, memory, mood, decision making, immune function, the absorption of vitamins, production of short-chain fatty acids, the ability to digest and absorb nutrients, synthesis of vitamins like B and K and gastrointestinal tract motility and function. Gut dysbiosis has been connected to obesity, irritable bowel disease (IBD), small intestine bacterial overgrowth (SIBO), rheumatoid arthritis, pain perception and other diseases and disorders.3

Diet, lifestyle and stress levels play a key role in maintaining a healthy gut. Stress can lead to the production of the hormone ghrelin in the gut. Ghrelin induces hunger as well as reducing anxiety and depression. Chronic stress can lead to chronically high levels of ghrelin in the gut, and possibly obesity. In a 2011 study, chronically stressed mice sought out high fat foods, opposed to mice that were genetically mutated to not respond to ghrelin and consequently didn’t seek out high fat foods. 4

The gut microbiome can be supported through nutrition. Consuming probiotic supplements5 and probiotic foods, such as yogurt are connected to an appreciable change in brain function.6 Lifestyle changes that can attenuate stress and support the gut microbiome can include meditation, exercise, gardening and eating meals with family and friends.

In the case of gut dysbiosis, for example SIBO (small intestine bacterial overgrowth) or other intestinal disorders or diseases, more specialized therapy should be undertaken. Visit a nutrition professional for further nutrition and wellness education or a doctor for diagnosis.


  1. Karen-Anne M Neufeld, Nancy Kang, et al. (2011) Effects of intestinal microbiota on anxiety-like behavior Commun Integr Biol. Jul-Aug; 4(4): 492-494
  2. Jason A. Hawrelak and Stephen P. Myers (2004) The Causes of Intestinal Dysbiosis: A Review Alternative Medicine Review
  3. Venket Rao, Alison C. Bested et al. (2009) A randomized, double-blind, placebo pilot study of probiotic in emotional symptoms of chronic fatigue syndrome Gut Pathog. 1;6
  4. Lukas Van Oudenhove, Shane McKie et al. (2011) Fatty acid-induced gut-brain signaling attenuates neural and behavioral effects of sad emotions in humans J Clin Invest. 121 (8)
  5. Chuang, G., Perello, M. et al. (2011) Ghrelin mediates stress-induced food-reward behavior in mice. J Clin Invest. 2011;121(7):2684–2692