AUTHOR: Dr. Jason Bush
We share a symbiotic relationship with our healthy gut microbes: We provide them with food and a place to live, and they help us in numerous ways, including with the break-down of the parts of our food that we cannot digest. Short chain fatty acids (SCFAs) are produced during microbial fermentation and these nutrients act as a source of energy.
SCFAs also help in other ways. As the ‘A’ in SCFA suggests, these molecules are acidic. This shouldn’t concern you – these acids are not strong enough or present in high enough concentrations to threaten you. However, they do have a strong effect on the microbial environment that exists in you gut.
First, a note on pH: The acidity of a system is measured using the pH scale, which ranges from less than 1 to 14. Fresh water typically has a pH of 7, and products that are ‘pH balanced’ generally fall between 6 and 8. Without going into too much chemistry, know that anything with a pH less than 7 is acidic and the lower the pH, the more acidic it becomes. In other words, the phrase ‘lowers the pH’ is the same as saying that something is becoming more acidic.
Now why would you want to lower the pH of a microbial ecosystem? Certain healthy bacteria produce acids and are tolerant of an ecosystem with a low pH. These include lactic acid-producing probiotics, such as Lactobacilli and Bifidobacteria. When these bacteria are introduced to dairy items to produce yogurt, they secrete lactic acid, which we perceive as the sour taste in these products.
But the acidity does something besides add flavour. The low pH created by the probiotics actually makes it harder for other bacteria to grow. The acids act like natural preservatives by preventing the growth of bacteria that lead to spoilage. It’s no wonder that – for centuries – people have been using fermentation to extend their shelf life of so many different types of food!
What does this mean for your gut microbiome? The principles are the same: Healthy gut microbes tolerate an ecosystem with a low pH while harmful bacteria do not. For example, pathogenic E. coli can grow at a range of different pH levels but grows best around pH 7. Therefore, maintaining a low pH in your gut by consuming probiotics and nurturing them with prebiotics will make it harder for harmful bacteria to grow and take over the ecosystem.
While there is always a low-level threat of becoming infected with a pathogenic gut microbe like E. coli, the risk of bacterial gut infections increases in certain settings. Such places include hospitals, institutions, and countries where clean water or food are scarce. While prevention cannot be guaranteed, supplementation with probiotics and prebiotics will ensure a lower gut pH, providing an added level of defense against bacterial gut infections.