Pre- and Probiotics

The bacteria in your bowels determine your health. Your gut flora can make you chronically inflamed, obese, cancerous or healthy, and your diet can determine your gut flora. We return to the basic wisdom that you are what you eat, but you can change (or exchange?) your gut flora.

A major follow up to the human genome project is an even more ambitious project to identify and characterize all of the microorganisms that live in or on humans. The justification for this “Human Microbiome Project” is the increasing realization that the bacteria of our guts, our “gut flora”, determine our health status.

Let’s get to the crux of the issue with a simple experiment from the biomedical literature. Two groups of people were identified based on whether they were obese or lean. Their bowel contents were removed, their intestines were flushed and their bowels were recolonized by insertion of either the gut flora from a lean person or an obese person. They were then told to resume their normal diets and were monitored. Obese with obese flora and lean with lean flora had the same weight pattern as corresponding untreated obese or lean. Obese with lean flora lost weight and lean with obese flora gained weight -- the gut flora determined weight gain or loss!

Another interesting observation comes from ambitious transplants of whole digestive tracts from stomach to rectum. Patients requiring this type of transplant are clearly compromised both by the disease conditions that required the removal of their intestines, etc. and by the immunosuppressants required for the transplant. The first approach was to purge the replacement intestines of their bacteria before the transplant. This produced a paradoxical low success. Better results, healthier transplanted organs and less need for immunosuppressants, were obtained when more of the gut flora were retained in the transplanted intestines. This was explained by the need for the healthy gut flora to support the transplanted intestines through the shock of the surgery. The dominance of the new flora also helped to suppress a return to the pattern of gut flora that may have contributed to the original need for a transplant.

The bacteria in your surroundings influence your gut flora. Clostridium difficile is a common spore forming bacterium of hospitals that can colonize patients treated with antibiotics. The longer that a patient is in a hospital, the higher their colonization with C. difficile. This also holds true for newborns -- their gut level of this nasty bug increases with the length of their hospital stay, even if they are exclusively breastfed. Medical representatives don’t want to discuss the source of the C. difficile, but it seems obvious that the hospital staff may be a major source. Perhaps their gut flora should be periodically cleared and replaced with healthy flora. In that way, the health care practitioners may be contributing to the cure of their patients by setting a good example.

The good gut flora that support health can be call “probiotics” and food or supplements that support the probiotics in your gut are called “prebiotics.” Typical examples of probiotics are fermenting bacteria, e.g. lactobacilli, commonly found in the living cultures of yogurts. It is not surprising that the bacteria in the guts of newborns that are exclusively breastfed are essentially just one species, Lactobacillus bifidus. That is why the diapers of breastfed babies just smell yogurty -- the typical feces smell (or stink) comes from compounds, e.g. skatole (also added to cigarettes), produced by adult gut flora. Even a single bottle of formula fed to an otherwise exclusively breastfed baby will cause a complete change in the gut flora and a substantial increase in health risks. That change can be observed in a lifelong increase in the risk of Helicobacter pylori that causes ulcers and stomach cancer.

Formula lacks the antimicrobial, immunological (antibodies and lymphocytes), gut maturational and other protective compounds of breast milk and causes inflammation in newborn guts. The inflammation, ironically, may be what keeps formula fed babies from dying (since it stimulates the immature immune system) without the immune support of breast milk. Formula causes a shift to an adult gut flora that results in a 10-100 fold increase in respiratory and digestive tract illnesses and a six point reduction in IQ compared to exclusively breastfed babies. The protective inflammation caused by formula may be analogous to the protective nicotine that prevents smokers from immediately succumbing to the acute inflammation or cancer initiation of tobacco smoke.

Mother’s milk provides special molecules, the bifidus factor, that support the growth of anti-inflammatory Lactobacillus bifidus. The bifidus factor is actually a group of related molecules that have chains of sugars, oligosaccharides, with a galactose on the end. These galacto-oligosaccharides are potent prebiotics. Not only does breast milk encourage the development of healthy probiotics in the newborn’s gut, but a recent study shows that even synthetic galacto-oligosaccharides with or without added probiotics result in an increase in anti-inflammatory gut flora when fed to school children.

Another indication of the potential power of probiotics and prebiotics is the increase in availability of probiotic yogurts and prebiotic supplements in supermarkets. Some of these may actually be beneficial in reducing chronic inflammation. We may even see probiotic fecal transplants offered at weight reduction and health spas.