Humans are home to many bacteria that, by some estimates, outnumber the human cells in our body by 10 to 1. For the most part, these bacteria are helpful friends that provide nutrients that our bodies cannot make. However, we have developed a rocky relationship with one of these microbial friends called Helicobacter pylori, which is a spiral shaped bacteria found in the lining of the deepest reaches of our stomach. These fascinating bacteria live in approximately 50% of the human population after being acquired through exposure to contaminated food and water. Scientists have shown that the bacteria can have a wide range of effects on their host including heart burn, ulcers, and stomach cancer. Just ask Dr. Barry Marshall, who shared the Nobel Prize in Physiology or Medicine for the discovery of H. pylori by swallowing a live culture of these bacteria and giving himself ulcers. Don’t worry! He later cured himself with readily available antibiotics. One of the reasons H. pylori is so important is because it is the biggest underlying factor in developing stomach cancer. Because of this, scientists and doctors have spent a lot of time and money attempting to understand why these bacteria have these effects.
The answer is complicated. Relationships between humans and our bacterial friends are regulated by factors such as our diet, stress, genetic variation (in the human and the bacteria), immune system, and even the places we live. Genetic studies have shown that the H. pylori DNA contain a lot of variability, making some bacterial strains containing bad DNA more cancerous than other strains. But, keep in mind that only a 3% of people that have H. pylori go on to develop cancer and, in fact, the majority of us live in perfect harmony with these bacteria. In fact, recent studies have suggested that the interplay between H. pylori and our immune system can actually calm some allergies and asthma. While factors like genetics and immune system cannot be directly affected, we can make an effort to eat well, exercise, and relieve stress to help keep us healthy. Most importantly, remember that our bodies play host to some friendly organisms that are close allies in the effort to keep us healthy.
This post was written by Dr. Martin Smith, PhD. He currently works at The Ontario Brain Institute studying brain diseases. To learn more about Martin and his research check out our Members page.