How we influence our gut microbial community.

Bacteria in our gut

The gastrointestinal microbiota is one the most diverse and dense places of bacteria in the body. Gut flora is established by the age of 1-2 years old and from there on out you develop a relationship with those microorganisms.  The relationship between some gut flora and humans is not merely commensal (a non-harmful coexistence), but rather a mutualistic relationship. The composition of human gut flora changes over time, when the diet changes, and as overall health changes. The upper digestive tract has few microbe populations but the main place you will find bacteria in the gut is the colon. It contains a densely populated microbial ecosystem with up to 1012 cells per gram of intestinal content. (1 )

The positive 

Many studies have shown that microbial diversity in the gut is correlated to having a healthy colon.  The normal microbiota of the large intestine is extremely important in preventing the establishment of pathogenic organisms .(2) Some microbes out compete the pathogens and others have metabolic products that prevent pathogens from becoming established. In this way these microbes are essential for our immune health. Not only are they important for immune health but the gut microbes are also responsible for helping us with our metabolism. Without gut flora, the human body would be unable to utilize some of the undigested carbohydrates it consumes, because some types of gut flora have enzymes that human cells lack for breaking down certain polysaccharides.

The negative 

When there is an imbalance of the normal microbe community by either a lack of diversity or lack of numbers, the epithelial layer the colon becomes susceptible to pathogen exposure. Enough exposure over a long period of time can result in chronic disease. Crohn’s disease is chronic inflammation of the lower intestine. Current thinking is that microorganisms are taking advantage of their host’s weakened mucosal layer and inability to clear bacteria from the intestinal walls, which are both symptoms of Crohn’s (3). Different strains found in tissue and different outcomes to antibiotics therapy and resistance suggest Crohn’s Disease is not one disease, but a variety of diseases related to different pathogens.

Behaviors for a healthy gut

A nutritional diet will help the health of your gut. Eating for a healthy gastrointestinal tract try adding this to your diet:

  • Eat plenty of fiber; think fruit, vegetables, and whole grains.
  • Eat three to five servings of fish each week.
  • Choose lean cuts of meat and remove the skin from poultry.
  • Stay well hydrated — water is best.
  • Avoid high-fat, processed, and fried foods.
  • Don’t overeat at any one sitting; stick to smaller, more frequent meals throughout the day.

Obesity and stress also play an important role in maintaining homeostasis within the gut. A healthy weight is correlated to less bowel problems. Regular exercise can contribute to a healthy weight and can lower stress levels. Exercise also helps with constipation and staying regular with bowel movements. The use of probiotics (microorganisms that are believed to provide health benefits when consumed) are recommended. Putting more “good” bacteria in the stomach can push out the “bad” bacteria.

Behaviors that put you at risk

Smoking and drinking are potentially harmful to the gut. Smoking can cause damage to just about any one of your major organ systems including your gut.  Protect your digestive tract by quitting smoking and avoiding secondhand smoke, since tobacco exposure has been linked to many conditions including heartburn, indigestion , esophageal cancer, pancreatic cancer, and colon cancer. Relying on vending machine fare, junk foods, and fast foods instead of fresh fruits, vegetables, and whole grains gets many of us into trouble.


Eating healthy, maintain a healthy weight, limiting stress, and reducing behaviors that put you at risk will give you a better probability of maintaining a healthy gut. The composition of human gut flora changes over time, when the diet changes, and as overall health changes. A microbial community in the gut that is more complex and diverse promotes a healthy gut.

  1. Guarner, F; Malagelada, J(2003). “Gut flora in health and disease”. The Lancet361 (9356): 512–9.
  2. Willey JM, Sherwood L, Woolverton CJ. 2014. Prescott’s Microbiology. Mcgraw-Hill EducationNew York, NY.
  3. Sartor, R Balfour (2006). “Mechanisms of Disease: Pathogenesis of Crohn’s disease and ulcerative colitis”. Nature Clinical Practice Gastroenterology & Hepatology3 (7): 390–407.

Writing assignment #2

As a healthcare professional, a colleague asks your opinion as to which HPV strains should be covered in a new treatment.

Cancer is a term which still strikes fear in the hearts and minds of most people diagnosed with it and even those who aren’t, but I don’t think anyone with cervical cancer would align themselves with groups fighting lung cancer, pancreatic cancer or colon cancer. While the commonality which exists because they are also a form of cancer there is a significant difference. That difference is the fact that cervical cancer, unlike the other cancers mentioned, is the result of a virus – human papillomavirus (HPV).

As a medical professional I would recommend a round of vaccines that cover strains of HPVs 16, 18, 31 and 45 first because these strains are known to account for up to 80% of cervical cancer(1.) This would be the most cost effective strains to cover given that one vaccine can’t cover all the strains of HPV.  The other strains of cancer causing HPV arnt as high risk as these first few so as a medical professional I would only recommend the round of vaccines that cover HPVs 16, 18, 31 and 45 if looking at just cost. If cost wasn’t a issue I would recommend HPV vaccine for all the strains across the board just to be safe.

Low risk HPV’s usually are not carcinogenic but can cause genital warts. For example, HPV types 6 and 11 cause 90% of all genital warts. HPV types 6 and 11 also cause recurrent respiratory papillomatosis, a disease in which benign tumors grow in the air passages leading from the nose and mouth into the lungs.(2.) HPV infections are the most common sexual transmitted infection in the U.S.  Centers for Disease Control estimates that more than 90% and 80%, respectively, of sexually active men and women will be infected with at least one type of HPV at some point in their lives. This is a scary number because around half of all these infections are high risk HPV’s that are known to be carcinogenic.

As a medical professional I would recommend that if you have access to get these vaccines you do so. This is to ensure that you have a lower risk of getting cancer associated with HPV if you are ever exposed which most likely you will be at some point in our life.

(1.)  Sarid R, Gao S-J. 2011. Viruses and Human Cancer: From Detection to Causality. Cancer Lett 218–227.

(2.) Human Papillomavirus (HPV) Vaccines. National Cancer Institute.