Mercola August 28, 2014
By Dr. Mercola
The truth of the old adage that “you are what you eat” is becoming increasingly clear, the more we learn about the microbiome—the colonies of microbes living in your gut, and indeed all over your body.
It is well established that your gut is your second brain providing more input to your brain than the brain provides to it. This is why your gut health is largely reflected in your gut bacteria, including your mental health and emotional well-being.
Your microbiome is essentially a historical accumulative composition of where you’ve been, who your parents are, who you spend intimate time with, what you eat, how you live, whether or not you’re interacting with the earth (gardening, for example), and much more.
As noted by Pat Schloss (a microbiologist with The Human Microbiome Project) in the video above, your microbiome is much like a fingerprint—it’s unique to you. Researcher Jeroen Raes has also suggested we might belong to one of a few “microflora types,” which are similar to blood types.
Your gut microbiome activity influences your immune responses, nervous system functioning, and plays a role in the development of any number of diseases, including obesity, cancer, and multiple sclerosis, just to name a few that I’ll address in this article.
How Intestinal Bacteria Can Induce Food Cravings
The bacteria in your body outnumber your cells by 100 to 1, and different bacteria have different nutritional needs.
According to recent research,1, 2 the nutritional preferences of your gut bacteria can influence your food cravings by releasing chemical signals through the vagus nerve, which connects your gut to your brain. According to one of the study’s co-authors, Carlo Maley, PhD:3
“Bacteria within the gut are manipulative… There is a diversity of interests represented in the microbiome, some aligned with our own dietary goals, and others not…
Our diets have a huge impact on microbial populations in the gut. It’s a whole ecosystem, and it’s evolving on the time scale of minutes.”
It’s already been well-documented that obese individuals have different bacteria dominating their microbiome than leaner individuals.
Research4 also suggests that as much as 20 percent of the substantial weight loss achieved from gastric bypass, a popular weight loss surgery, is due to shifts in the balance of bacteria in your digestive tract. With regards to the featured research, Forbes5 reports:
“‘Microbes have the capacity to manipulate behavior and mood through altering the neural signals in the vagus nerve, changing taste receptors, producing toxins to make us feel bad, and releasing chemical rewards to make us feel good,’ said study co-author Athena Aktipis, PhD.
The good news, the researchers tell us, is that we can influence changes in our gut dwellers through dietary choices.
‘Because microbiota are easily manipulatable by prebiotics, probiotics, antibiotics…and dietary changes, altering our microbiota offers a tractable approach to otherwise intractable problems of obesity and unhealthy eating.’”
Diet Can Rapidly Alter Gut Bacteria
Indeed, another recent study6, 7 highlights the speed with which you can alter the balance of your gut bacteria. Here, researchers at Massachusetts Institute of Technology (MIT) monitored two people over the course of one year; collecting daily stool samples and correlating the gut bacteria from day to day with diet and other lifestyle factors such as sleep, mood, and exercise.
One of the participants developed diarrhea during a two-week trip to another country, which resulted in significant changes in the balance of gut bacteria.
A case of Salmonella food poisoning struck the other participant, which resulted in a drastic change in gut bacteria. Salmonella bacteria rose from 10 percent to nearly 30 percent, and the colonies of beneficial bacteria were nearly wiped out.
Once the individual recovered, beneficial bacteria quickly rebounded to about 40 percent of the total microbiome, but most of the strains were different from the original strains. According to senior author Eric Alm:8
“On any given day, the amount of one species could change manyfold, but after a year, that species would still be at the same median level. To a large extent, the main factor we found that explained a lot of that variance was the diet.”
The most prominent changes correlated with the individuals’ fiber intake. Greater amounts of fiber affected about 15 percent of the gut bacteria, resulting in greater proliferation of them.
Gut Bacteria May Reveal Colon Cancer, and Might Play a Role in MS
Your microbiome may even reveal your risk for, or presence of, colon cancer. A total of 90 people participated in this study;9, 10 thirty were healthy; 30 had precancerous intestinal polyps; and 30 had been diagnosed with advanced colon or rectal cancer. After assessing the composition of each person’s microbiome, it became apparent that microbiome analysis (using a fecal test) might be a viable way to screen for precancerous polyps and colorectal cancer.
According to their findings, adding microbiome analysis to other known risk factors for precancerous polyps resulted in a 4.5-fold improved prediction for the condition. Adding microbiome analysis to risk factors for invasive colorectal cancer resulted in a five-fold improvement in their ability to predict cancer.
In related news, researchers have also linked certain gut microbes to the development of multiple sclerosis (MS), and/or improvement of the condition. The paper, published in the Journal of Interferon and Cytokine Research,11 describes three immunological factors associated with the gut microbiome that relates to inflammatory responses in MS patients:
T helper cell polarization
T regulatory cell function
B cell activity
Previous research has suggested that altering the gut microbiome by adding bacteria such as Lactobacillus, and/or worm-type organisms like Schistosoma and Trichura, can be helpful in reducing MS symptoms. Apparently, these microorganisms have a beneficial effect on cytokine production throughout the body, thereby reducing systemic inflammation. Cytokines are cellular messengers that regulate inflammatory responses. According to the authors: “Whether future therapeutic approaches to MS will employ commensal-based products depends on nuanced understanding of these underlying mechanisms.”