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You might think that your digestive system serves only to help you process and extract the nutrients in your foods. It does that, of course, but it does much, much more.
In fact, your gastrointestinal tract has been called the “second brain” – a complex system that sends and receives all kinds of information to and from your “first” brain. The “brain” in your gut has a variety of receptors that gather information about conditions in your digestive tract. It then sends signals to your “first’ brain, which uses that information to control digestive function.
An important player in all of this is something called the gut “microbiome” – which is really a world within you. Your microbiome is an entire ecosystem composed of trillions of diverse organisms (including bacteria, fungi and viruses) – weighing between two and six pounds- which has profound effects on your health.
One of the primary functions of the microbiome is to break down dietary fiber, since the human body lacks the machinery to get the job done. The microbiome also supports the health of your immune system (much of which resides in your gut), helps keep out foreign invaders that could make you sick, and manufactures several essential vitamins.
With so many important roles that it has in protecting your health, there is increasing attention to the role that diet plays in maintaining the health of your microbiome.
While we don’t know exactly what the ideal composition of the microbiome should be, we do know that the more diverse the population of inhabitants in your gut, the better. The foods you put into your system have a big influence on maintaining a healthy balance of the microbes in your gut which, in turn, helps your two “brains” to optimally work together.
Prebiotics are the compounds in many of the high fiber foods that you eat. While humans lack the ability to break down the fiber that we consume in foods like fruits, vegetables, beans and whole grains, the microbes in your gut are more than happy to do the job for you, in a process referred to as “fermentation”.
As the microbes ferment the dietary fiber that you eat, they produce certain compounds that serve as fuel for the cells that line your intestinal tract, thus helping to keep it healthy.
Prebiotic compounds are particularly abundant in bananas, onions, garlic, leeks, asparagus, artichokes, tomatoes, plums, apples, nuts, soybeans and whole-wheat foods.
The word “probiotic” derives from the Greek (“promoting life”). And probiotics certainly do just that in your digestive tract. Probiotics are the “good” bacteria (sometimes called live cultures) that you can consume from foods or supplements. Probiotics are the same bacteria that reside in your gut. Taking in probiotics can help to balance the populations of the various types of bacteria in your gut, which, in turn, promotes gut health.
While the idea of consuming bacteria may not sound appealing, it’s likely that you already consume them without realizing it. Probiotics are found in many fermented foods. Fermentation is a natural process in which bacteria convert sugars and other carbohydrates in foods into acids. That’s why many naturally fermented foods have a tangy taste.
For many people, the most common source of probiotics is fermented dairy products such as yogurt, kefir and certain aged cheeses. In fact, one of the most common strains of probiotic bacteria that reside in your intestines is Lactobacillus acidophilus, which is found in yogurt.
You can also obtain beneficial probiotics from fermented vegetables such as pickles, kimchi, olives and sauerkraut (only when sold refrigerated; canned products are heated during processing, which destroys the beneficial bacteria). Other sources include fermented soy products such as miso and tempeh, cultured non-dairy yogurts (look for “live active cultures” on the label) and kombucha beverages.
Susan is the Sr. Director of Worldwide Nutrition Education and Training at Herbalife, where she is responsible for the development of nutrition education and training materials, and is one of the primary authors of the Herbalife-sponsored blog, www.discovergoodnutrition.com. She is a Registered Dietitian and holds two Board Certifications from the Academy of Nutrition and Dietetics as a Certified Specialist in Sports Dietetics, and a Certified Specialist in Obesity and Weight Management. Susan is also a Fellow of the Academy of Nutrition and Dietetics.
Susan graduated with distinction in biology from the University of Colorado, and received her master’s degree in Food Science and Nutrition from Colorado State University. She then completed her dietetic internship at the University of Kansas. Susan has taught extensively and developed educational programs targeted to individuals, groups and industry in her areas of expertise, including health promotion, weight management and sports nutrition.
Prior to her role at Herbalife, she was the assistant director of the UCLA Center for Human Nutrition, and has held appointments as adjunct professor in nutrition at Pepperdine University and as lecturer in nutrition in the Department of Food Science and Nutrition at Cal Poly San Luis Obispo.
Susan was a consultant to the (then) Los Angeles Raiders for six seasons, and was a contributing columnist for the Los Angeles Times Health Section for two years. She is a co-author of 23 research papers, 14 book chapters, and was a co-author of two books for the public: “What Color is Your Diet?” and “The L.A. Shape Diet” by Dr. David Heber, published by Harper Collins in 2001 and 2004, respectively.