While “gut” refers to the digestive system, its use in relation to prebiotics and probiotics has focused on the lower gastrointestinal tract from stomach to the intestines. Specifically, it is in the colon (large intestines) where most bacteria reside.
Markers of a healthy gut include the following: gastrointestinal symptoms such as abdominal pain and diarrhea as well as diseases like inflammatory bowel disease and colon cancer are not experienced. Also, unfavorable conditions such as leaking gut and inflammation of the intestinal lining should be absent. Accordingly, the presence of good bacteria plays a significant role. The number of bacteria fluctuates somewhat with age, illness, antibiotic treatment and some components of our diet.
Prebiotics are food components like fiber that cannot be digested but help stimulate growth of good bacteria in the colon thus are said to be the food for the good bacteria. Prebiotics occur naturally in foods and fruits, vegetables and whole grains.
By the word itself, probiotics are beneficial to health. They are live bacteria that confer a health benefit when taken in sufficient amounts. Fermented products such pickles, sauerkraut (cabbage), miso, yogurt, cheese and sour cream are the dominant probiotics. Harvard (2020) explains that while most fermented foods are probiotic foods, not all fermented products contain probiotics as some foods undergo steps that remove the probiotic as in beer or wine. Some food processing techniques make probiotics inactive as in the case of canning and baking. Processing and storage can affect survival of live microorganisms in food.
One great concern is, are we taking enough? Does a serving of a so-called probiotic contain enough of the good bacteria? Does it even contain enough of what is claimed? At the same time, how much of a particular food should be eaten so as not to be in excess? There is no clear answer yet. The practical advice is to make as many sources as possible part of the diet while observing the principles of moderation, variety, adequacy and balance (MoVABa). Note that there are many kinds of bacteria in the intestines but only a few are used in some foods. Probiotics given as supplements are to be reserved for certain ailments thus not part of the daily diet.
