What is gut health? That's the blurry 800-pound gorilla in the room

No generally accepted diagnostic criteria exist to define what a healthy gut looks like. Practitioners have no tests, as they do for cardiovascular health, liver function or a host of other health parameters, that would yield values that could tell them if a given patient is fine or is approaching a danger zone.

And complicating the picture is the notion that we’re not dealing with a single species. Rather, gut health deals with a community of organisms: the primate host with all of its genetic variations from individual to individual, and the varying number of microorganisms living in and on that host, with all of their own genetic variations.  And oh, by the way, that suite of single-celled chemical factories is unique to each host, and can show huge differences in the number of species and their relative populations from person to person.

What isn’t there can’t hurt you​

So experts agree that at the present level of scientific understanding, gut health is more about what isn’t as opposed to what is. It’s like one of those illustrations in which the true image emerges in the negative space formed by detailed sub-images on the periphery, in this case all the things that can go wrong with the human digestive system forming the boundaries.

“First, a healthy gut is the lack of issues with digestion,”​ said Scott Bush, vice president of marketing for DuPont Nutrition and Health.  “You can almost define it by what it isn’t as opposed to what it is.”​

DuPont markets a variety of probiotic ingredients primarily acquired when it bought Danisco in 2011.  Among DuPont’s offerings are the Howaru brand of proprietary probiotic strains.

“Everybody’s gut biota is different and science has not come up with an idea of what the ideal gut bacteria makeup looks like,”​ said Mike Bush, vice president of business development for Ganeden Biotech, which markets a proprietary strain of bacillus coagulans for functional food and beverage applications branded as Ganeden BC30. “Ideally a healthy gut is functioning optimally in a metabolic sense. It is good at metabolizing nutrients and is symptom-free,”​ he said.

Michael Shahani, chief operations officer for Nebraska Cultures, echoed those sentiments. “Almost everyone complains of stomach issues from time to time,” ​he said, and the periods in between are what constitute ‘health.’  

“Well-regulated and healthy digestion is something a lot of people just don’t have. A lot of people take it for granted that they will have some problems with their digestion, whether it is diarrhea, constipation or gas,”​ Shahani said.

Lack of definition a problem for researchers​

Robert Hutkins, PhD, a professor of food microbiology in the school of Food Science and Technology at the University of Nebraska Lincoln, said the lack of a more fixed definition of what gut health consists of is a constant question for researchers.

“Whenever we have these scientific conferences that is always one of the session titles: ‘What is Gut Health?’ ”​ Hutkins said. “I wish I had an easy answer for you but it’s not that simple. Even healthy people have issues with foods that don’t sit well with them. People might be trying to eat more fiber but they complain that it give them gas or makes them feel bloated.”​

The question, of course, is why?  Why can some people metabolize certain foods just fine, where others have serious side effects? One answer for that conundrum of not having an answer to the big question is to take an approach of wearing down the mountain one grain of sand at a time, he said.

“When we’ve done studies in our lab with pre- and probiotics, a lot of times we just use college students (who can be expected to have few gut heath issues).  We are looking at changes in their microbiota with supplementation,” ​he said.

New data streams​

One area that might provide meaningful data in the near future is the accounts of the outcomes of fecal transplants, a therapy that is becoming more commonplace, Hutkins said.  Once a last-ditch therapy for treating severe cases of c. difficile​ infection that had almost destroyed certain patients’ digestive processes, the treatment is gaining more mainstream traction and more refined methods are under development to replace the practice’s early, crude iterations. But underlying the trend is the opportunity to gather useful data in extreme cases, situations that could never be considered in an ethical study design, Hutkins said.

Another area that holds promise is using the growth of personalized genetic databases to match up variations in the host, human genome with differences in the makeup of gut microbiota. The fairly recent announcement by certain researchers of their identification of broad gut ‘enterotypes’ that mimic the concept of different blood types might be premature, Hutkins said, but it is a tantalizing area of research.

“There is a lot of work being done looking at what is in the host genome that might influence the bacteria that live in the gut. There could be genes that are responsible for the makeup of those populations,”​ he said. “Researchers are looking at the profile of bacteria that live in the gut and how the whole assembly is capable of being manipulated.”​

DuPont’s Scott Bush said gene-based research is a big area inquiry for his company.

“I think it’s really interesting science and we have a very active genomics program in general. We are looking at things like, what is the overall microbial population?  How does it vary from person to person, from region to region or from culture to culture?  How is it impacted by a certain diet?” ​Bush said.

Smaller hills to climb​

But that research is a long way from yielding an overall picture. In the meantime, DuPont, like other probiotic suppliers, has to content itself with choosing smaller hills to climb.

“I would stay we are still very early in a lot of that science. What we try to do is to put together a probiotic formuation that can be effective in a broad scope of people to help maintain healthy gut function. ​There are a lot of studies we do in trying to show that probiotics help maintain health such as to put populations together and show that a group that doesn’t get the probiotic has an indication that the group that does get the probiotic doesn’t show or shows to a lesser extent,”​ Bush said.

“Those indications are things that everybody knows such as diarrhea, bloating or constipation. Or we have done studies with IBS (inflammatory bowel syndrome),”​ he said.