WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
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.”
When It Comes to Inflammation, Your Microbiome Rules
MS certainly is not the only disease caused by chronic inflammation in your body. In fact, most chronic disease has inflammation as an underlying factor. It’s important to realize that your gut is the starting point for inflammation—it’s actually the gatekeeper for your inflammatory response. As suggested above, various gut microorganisms can either trigger or subdue the production of inflammatory cytokines. Most of the signals between your gut and your brain travel along your vagus nerve—about 90 percent of them.12 (Vagus is Latin for “wandering,” aptly named as this long nerve travels from your skull down through your chest and abdomen, branching to multiple organs.13)
Cytokine messengers produced in your gut cruise up to your brain along the “vagus nerve highway.” Once in your brain, the cytokines tell your microglia (the immune cells in your brain) to perform certain functions, such as producing neurochemicals. Besides influencing your hunger and cravings for certain foods, as discussed earlier, these chemical messages can also affect your mitochondria, impacting energy production and apoptosis (cell death). They can also affect the very sensitive feedback system that controls your stress hormones, including cortisol, for better or worse.
So, an inflammatory response can begin in your gut, travel to your brain, which then builds on it and sends signals to the rest of your body in a complex feedback loop. It isn’t important that you understand all of the physiology here, but the take-away is that your gut flora significantly affects and controls the health of your entire body.
Your Gut Flora Is Perpetually Under Attack
Your microbiome—and therefore your physical and mental health—are continuously affected by your environment, and by your diet and lifestyle choices. If your gut bacteria are harmed and thrown out of balance (dysbiosis), all sorts of illnesses can result, both acute and chronic. Unfortunately, your fragile internal ecosystem is under nearly constant assault today. Some of the factors posing the gravest dangers to your microbiome are outlined in the following table.
| Refined sugar, especially processed high fructose corn syrup (HFCS) | Genetically engineered (GE) foods (extremely abundant in processed foods and beverages) | Agricultural chemicals, such as herbicides and pesticides. Glyphosate appears to be among the worst |
| Conventionally-raised meats and other animal products; CAFO animals are routinely fed low-dose antibiotics and GE livestock feed | Gluten | Antibiotics (use only if absolutely necessary, and make sure to reseed your gut with fermented foods and/or a good probiotic supplement) |
| NSAIDS (Nonsteroidal anti-inflammatory drugs) damage cell membranes and disrupt energy production by mitochondria | Proton pump inhibitors (drugs that block the production of acid in your stomach, typically prescribed for GERD, such as Prilosec, Prevacid, and Nexium) | Antibacterial soap |
| Chlorinated and/or fluoridated water | Stress | Pollution |
Your Diet Is the Most Effective Way to Alter Your Microbiome
The best way to optimize your gut flora is through your diet. A good place to start is by drastically reducing grains and sugar, and avoiding genetically engineered ingredients, processed foods, pasteurized foods, and chlorinated tap water. Pasteurized foods can harm your good bacteria, and sugar promotes the growth of pathogenic yeast and other fungi. Grains containing gluten are particularly damaging to your microflora and overall health.14, 15 A gut-healthy diet is one rich in whole, unprocessed, unsweetened foods, along with traditionally fermented or cultured foods. Chlorine in your tap water not only kills pathogenic bacteria in the water but also beneficial bacteria in your gut.
Fermented foods are also a key component of the GAPS protocol, a diet designed to heal and seal your gut. Your goal should be to consume one-quarter to one-half cup of fermented veggies with each meal, but you may need to work up to it. Consider starting with just a teaspoon or two a few times a day, and increase as tolerated. If that is too much (perhaps your body is severely compromised), you can even begin by drinking a teaspoon of the brine from the fermented veggies, which is rich in the same beneficial microbes.
You may also want to consider a high-potency probiotic supplement, but realize that there is no substitute for the real food. A previous article in the Journal of Physiological Anthropology16 makes the case that properly controlled fermentation amplifies the specific nutrient and phytochemical content of foods, thereby improving brain health, both physical and mental. According to the authors:
“The consumption of fermented foods may be particularly relevant to the emerging research linking traditional dietary practices and positive mental health. The extent to which traditional dietary items may mitigate inflammation and oxidative stress may be controlled, at least to some degree, by microbiota.”
They go on to say that the microbes associated with fermented foods (for example, Lactobacillus and Bifidobacteria species) may also influence your brain health via direct and indirect pathways, which paves the way for new scientific investigations in the area of “nutritional psychiatry.”
Your Body Is a Conglomerate of Bacterial Colonies
You’re not only surrounded by bacteria in your environment; in a very real way, you are them. Your body is in fact a complex ecosystem made up of more than 100 trillion microbes that must be properly balanced and cared for if you are to be healthy. Pamela Weintraub skillfully describes the symbiotic relationship between humans and microorganisms in her June 2013 article in Experience Life magazine.17 This system of bacteria, fungi, viruses, and protozoa living on your skin and in your mouth, nose, throat, lungs, gut, and urogenital tract, is unique to you.
It varies from person to person based on factors such as diet, lifestyle, health history, geographic location, and even ancestry. Your microbiome is one of the most complex ecosystems on the planet as for every bacteria you have, there are 10 bacteriophages or viruses. So not only do you have 100 trillion bacteria, you have one quadrillion bacteriophages.
All of these organisms perform a multitude of functions in key biological systems, from supplying critical vitamins to fighting pathogens, modulating weight and metabolism, and much more, and when your microbiome falls out of balance, you can become ill. Your microbiome also helps control how your genes express themselves. So by optimizing your native flora, you are actually controlling your genes! All of this is great news, because while your microbiome may control your health, you can control which bacteria have the upper hand—health-promoting ones, or disease-causing ones—through your diet and lifestyle.