Bacteria in your gut: How are they good for you?

By:  Corey Howard, MD, FACP

Bacteria in your gutDid you know there are over 2 ½ pounds of bacteria inside of your intestinal tract?  Yes, that’s right, over 2 ½ pounds!  These bacteria play a vital role in the health of your intestinal tract and your health overall as well.  The vast majority of your immune system presides in the gastrointestinal tract and you have over 1000 different types of bacteria and trillions of bacteria total.  That truly is amazing.  In order to keep these bacteria healthy you need to eat the right kinds of foods and limit antibiotic exposure when possible.

Bacteria are introduced into your gut at birth and the types of bacteria, the so-called gut biome or microbe community, develops over time and is shaped by many factors.  Time Magazine reported in 2013 on a study that was done in Europe on 300 Danish Volunteers who were both lean and obese.  They found that the group that had fewer different types of bacteria had higher amounts of inflammation, greater insulin resistance (a risk factor for diabetes) and other problems related to metabolism.  Also, the patients who had less diversity in the bacteria population tended to gain more weight over time increasing their risks to all of the complications due to obesity including diabetes, heart disease, depression and cancer.  Another interesting study that same article reported on was a French study which revealed that the people who were obese and had fewer different types of bacteria in the gut saw improvements when placed on a low calorie diet and when they lost weight.  Their “diversity” in the bacteria population improved as well.  That gives us evidence that diet can improve your intestinal bacteria makeup.

Another important role the bacteria play in your body is your immune system. These bacteria help you develop immune cells that fight off invaders that try to enter through the intestinal tract.  The interesting thing is that the cells that are made in the gut by this interaction (bacteria and your body) have immune effects beyond the gut and actually go into your bloodstream.  There are several types of cells that help out and include macrophages (these are pac-man like cells that eat debris from immune reactions), toll-like receptors (these help repair your gut when damaged due to a variety of causes), and other white blood cells that help you fight infection.

The last area to discuss is carbohydrate metabolism and absorption from your intestinal tract.  Bacteria in your intestines help you digest certain carbohydrates making them available for you to absorb.  The bacteria make up can affect this absorption and it is related to your diet as well as environmental factors over time.  Studies show an increase in obesity with certain bacterial profiles that researchers are connecting to the way those bacteria metabolize and allow for absorption of carbohydrates in your diet.

The bacterial profile in your intestinal tract is very important for your overall health.  The more information researchers can obtain the better the recommendations we can make for you.  The bacteria in your gut will adapt to your diet and therefore it is in your control.  It is not quite as simple as that but here are a few tips:  Fermented type foods support the growth of  good bacteria.  Try to avoid antibiotics when possible because they tend to kill off the good bacteria, allowing the bad ones to grow.  There is some evidence behind the use of probiotics.  However, there are many brands over the counter touting their effectiveness  but, usually they do not have enough evidenced-based science to help you make a decision.  That is unless you have some idea of the makeup of the types of bacteria you have.

The science is not solid yet with regard to bacteria in your gut and it is prudent to not jump on each product that comes along touting how great it is for intestinal health without studying it a bit.  This field is in it’s infancy and I suggest a few different types of tests in my practice that my patients find useful when trying to decide what to do.  In the end, a high nutrient density diet, consisting of vegetables and whole grains as well as fermented foods, will help you and the bacteria in your intestines the most.

1048 Goodlette Road, Suite 101, Naples, FL 34012  .  239-325-6504  .

About Corey Howard, MD, FACP
Dr. Howard practices Lifestyle Medicine in Naples.  He is a fellowship trained gastroenterologist and board certified in Internal Medicine as well as Anti-Aging and Regenerative Medicine.  He has also obtained Professional Certification in Plant Based Cooking.   He has regular seminars and courses to teach how to live a better life through healthy habits.

To contact Dr. Howard go to: or email him directly at

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