In 1995, the Journal of Nutrition printed a landmark article in the study of gut flora. Written by Professors Glenn Gibson (University of Reading) and Marcel Roberfroid (Université Catholique de Louvain), Dietary Modulation of the Human Colonie Microbiota: Introducing the Concept of Prebiotics fueled the interest in gut flora and helped bring about the flurry of current research on issues pertaining to the intestinal tract.
And — as you may know — the gut is central to your health and well-being. Notice the title of Gibson and Roberfroid’s study, though. It does NOT talk about probiotics. Rather, it addresses something newly recognized and coined in 1995: Prebiotics.
That is where this story begins.
What are prebiotics and why should you be concerned about them?
diet and cancer
National Cancer Institute (1985) public domain
For years, health scientists were aware of a class of fibers and starches known as “roughage” or “bulking agents.” They were considered indigestible by the body, but useful for cleansing the colon and for their laxative effect.
Gibson and Roberfroid saw another purpose for roughage: it serves as a food source for gut microbes – the three or so pounds of microorganisms that live in your intestinal tract.
Most of these microorganisms are helpful to you. They are known as “probiotics.”
Having determined the importance of certain forms of roughage to these colonies of (primarily) bacteria, the scientists coined a special name to describe these probiotic propagators: “prebiotics.”
Do you remember the tale of the good wolf and the bad wolf?
“Inside each of us,” said the elder to his grandson, “live two wolves. One is good, and one is bad. And these wolves constantly fight one another to see which will gain control over our actions.”
Mesmerized at the thought, the boy cautiously asked, “Which one will win, Grandfather?”
“It is up to you, my son,” counselled the grandfather. “The wolf that will win is the one you feed.”
The same goes for gut flora. If you want the good microbes to win, you must feed them.
And to do that, you need prebiotics.
What are the two “true” prebiotics?
If Gibson and Roberfroid’s work launched a new era of gut biology research, Marcel Robenfroid’s paper, Prebiotics: The Concept Revisited (2007) gave it a good shaking. In it, he declared that there are only two known types of bulking agents that may accurately be termed “prebiotic.” (Note: This paper was written in 2007, remember, other candidates have been proposed since. We will discuss that in the next article — after the interview with Dr. Gibson.)
That got my attention.
Only two true prebiotics exist? Well – what are they? If there is something crucial to maintaining a healthy balance in gut flora, I want to know what it is. Dr. Haley has already sold me on the importance of intestinal microbes.
When my gut is healthy, I am healthy. When it is not, I am not.
Roberfroid is a pharmaceutical scientist, and he was writing for a scholarly journal. I don’t know how long it has been since you tried to wade through an academic paper, but it’s not easy – even for academics.
Let’s unwrap the mystery, though, beginning with Roberfroid’s definition of a prebiotic:
A prebiotic is ‘‘a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health.’’
By “selectively fermented,” Roberfroid is pointing out there are some ingredients that some microbes feed on (ferment), and that the end result is aimed at the health of the “host” (that is you and me).
The microflora (“gut flora”) are the trillions of organisms that live in your intestinal tract and make up, perhaps, three pounds of your body weight. Most are bacteria. This biomass can help you get and stay healthy.
Like a garden, though, it must be cultivated.
In the 2007 study, Roberfroid proposed several characteristics that should be present for any substance to be classified as truly “prebiotic.”
Prebiotics, said the world-renowned scientist are:
Considered to be food or food ingredients
Show resistance to gastric acids, gastric enzymes, and gastrointestinal absorption
Are capable of being fermented by the flora normally considered health-promoting
Citing studies where human microflora were fed with varying diets, Roberfroid identified two types of matter, both classified as “essentially nondigestible oligosaccharides,” met all criteria.
These two true prebiotics are inulin and trans-galactooligosaccharides (TOS).
A Chicory Flower (via Bruce Marlin, Creative Commons, image cropped)
Can I obtain true prebiotics from foods?
Following the trail of logic:
Gut flora are essential to health
Gut flora need prebiotic food in order to flourish
There are only two true prebiotics
The next step follows necessarily, for anyone desiring to either regain or maintain optimal health: Where can I get those prebiotics?
Where can I find inulin?
The most popular source of inulin is chicory root. It not only serves as a prebiotic, but aids in the absorption of minerals – calcium, most notably. The Jerusalem artichoke is also a good bet. Lesser concentrations of inulin are found in garlic and onions.
Where can I find trans-galactooligosaccharides (TOS)?
One of the best sources of trans-galactooligosaccharides is mother’s milk. Chances are, you haven’t nursed in a while, though. However … reports say that hiring a personal wet nurse has recently become the rage with wealthy Chinese men … eager to pay a couple of grand per month for the service.
Critics are incensed, pointing out that less than a third of Chinese children are fortunate enough to be nursed. Most mothers can’t afford the time off work.
TOS is also produced commercially – primarily by being synthesized from cow’s milk. It is then added to cultured milk products (yoghurt and kefir, for instance).
What are the unanswered questions concerning prebiotics?
This is an excellent question to ask, concerning any and every subject. Our decisions are normally based on the best available data – but there are times when that data is obsolete or incorrect.
A close study of prebiotics leads to questions like these:
Do prebiotic food substances really feed ONLY the helpful gut flora? Is it not possible one can unwittingly feed the “bad guys” too?
What is the recommended dosage of prebiotics?
Are TOS and GOS really synonyms for the same thing?
Could there be harmful effects from boosting my intake of prebiotics?
How can I be sure of the levels and types of prebiotics in the foods I eat? What should I look for to find the best sources?
What are the symptoms of a gut flora imbalance?
Have more prebiotic sources yet been identified?
Professor Roberfroid is now in retirement — a big loss to the academic community — but Professor Glenn Gibson is still studying, teaching, and writing about prebiotics, probiotics, and other gut health issues. I have been in touch with him and hope to soon be able to report on the latest research findings.
I also hope to interview Dr. Michael Haley soon. He is an expert on intestinal health and can tell us what part Aloe vera gel, taken internally, can play in helping to bring about healing of those in need of healing and continued health for those who are already blessed with the many benefits of wellness.