Discovering Links Between Gut Bacteria And Brain Function
Forbes/Wolfe Emerging Tech Report
David Perlmutter, MD, FACN, ABIHM is a Board-Certified Neurologist and Fellow of the American College of Nutrition. Dr. Perlmutter serves as an associate professor at the University of Miami School of Medicine. He has contributed extensively to the world medical literature with publications appearing in the Journal of Neurosurgery, the Southern Medical Journal, Journal of Applied Nutrition and Archives of Neurology.
He is the author of many books, including: The Better Brain Book, Raise a Smarter Child By Kindergarten, Power Up Your Brain: The Neuroscience of Enlightenment, the #1 New York Times bestseller Grain Brain–The Surprising Truth About Wheat, Carbs and Sugar–Your Brain’s Silent Killers, New York Times bestseller The Grain Brain Cookbook, and New York Times bestseller Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain–For Life, and is recognized internationally as a leader in the field of nutritional influences in neurological disorders.
Tell us a bit about the relationship between the human microbiome and the brain.
We’ve really done some incredible work over the years from the diagnostic prospective, but when it comes to actionable treatments, we’ve been at a loss for maladies involving the brain, particularly with major issues such as Alzheimer’s, autism, Parkinson’s and depression. We’re starting to discover the incredible role of the microbiome–the 100 trillion organisms living within the human intestine–in virtually every important physiological process that happens in the human body. It’s become very clear that the changes in these processes underlie our most important brain related disorders.
We now understand that gut bacteria play a critical role in regulating immunity and inflammation. As it turns out, especially regarding inflammation, this is a cornerstone of virtually every degenerative condition of the brain that you might describe. Even diseases that are not classically considered ‘degenerative,’ such as autism, are also primarily considered inflammatory disorders. It’s a very exciting time to be involved in neurology, as we have discovered that the answer to some of our most feared brain disorders may actually reside outside of the brain.
What are some of the links that have been shown between the gut and the brain?
We now know that exercise, lack of obesity and keeping blood sugar low are associated with reduced risk of Alzheimer’s disease. Data has shown a dramatic correlation of very subtle elevations of blood sugar and future risk, up to seven years later, of becoming demented. That’s powerful information that we can’t sweep under the rug. According to a study from the Mayo Clinic published in the Journal of Alzheimer’s Disease, individuals that have a higher carbohydrate diet have about an 88% increased risk of Alzheimer’s, whereas those individuals whose calories come more from fat have about a 44% reduction in risk for becoming demented. That’s powerful information that I think the public needs to know now, not 10 to 20 years from now when the interventional trials have been done.
Those are the types of data that have gone into books such as Grain Brain—which advocates a very low carbohydrate, higher good fat diet—and Brain Maker, which focuses on this incredible role of the gut bacteria, in terms of inflammation.
What are some other actionable steps that can be taken regarding keeping our gut microbiomes healthy?
I will first say that we are at a very primordial stage in our understanding about this microbiome and its role in brain health. That was the purpose of writing Brain Maker—to provide a fairly in-depth overview as to where we are right now in 2015, and what the future may hold. In order to protect your microbiome, you can reduce your consumption of antibiotics, your non-steroid anti-inflammatory drugs (NSAIDs), acid blocking drugs, and eat more foods that are enriched with probiotics. Eat foods that have been fermented, as well as foods that contain what are called ‘prebiotic fiber,’ to nurture good gut bacteria. The notion of antibiotics overuse was described by Dr. Martin Blaser in his book Missing Microbes [Editor’s note: Dr. Blaser was featured in the June 2014 Forbes/Wolfe Emerging Tech Report].
I’m saying this based upon 47 pages of peer reviewed research, all of which appear in Brain Maker. The recommendations made in Grain Brain and made in Brain Maker are sound overall for your health anyway. If you have a choice, why not deliver your children by vaginal delivery? Why not reduce the antibiotic exposure for our children as is recommended by the American Medical Association? Why wouldn’t you want to reduce sugars and carbs in your children’s diet and your diet as well? I provide the science that supports that. But at the end of the day these are recommendations that are good for the microbiome.
Is everyone’s microbiome different? If so, does that mean there are different answers for diet for different people?
Everyone’s microbiome is different, but there’s still so much we don’t know. What we do know is that the most fundamental influence in terms of shaping the gut bacteria—in terms of diversity and complexity —is the food choices that we make. We know that people who have very complex and diverse microbiomes that move to Western countries and switch to a Western diet rapidly lose their diversity, and this has been associated with increased risk for various inflammatory disorders.
Is there a way for consumers to understand the makeup of their microbiomes and to try to take proactive steps to increase their microbial diversity?
There are stool tests and to some degree, certain blood tests will give you inferential information in terms of your microbiome. What we do in Brain Maker is provide readers with a little quiz they can take to determine if they’ve threatened their microbiome and/or have any ongoing issues that may reflect that the microbiome has been challenged. Things like being born by C-section, getting antibiotics early in life, having your tonsils out, being overweight, being depressed, being food sensitive, food allergies, gluten sensitive, having an autoimmune condition—these are all indications that relate back to the microbiome. It’s fair to say that by and large, the microbiomes of most people living in Western cultures are less than ideal.
What are some of the new therapeutic approaches we’re seeing in this space?
A Dutch doctor performed fecal transplants on 250 humans with Type 2 diabetes with material from healthy, lean donors. His results were nothing short of breathtaking, as he was able to reverse Type 2 diabetes by changing out the fecal microbial milieu of these individuals who were affected. Dr. Thomas Borody in Australia has reversed symptoms of Multiple Sclerosis in a handful of individuals through fecal microbial transplant. The University of Arizona has just completed the recruitment phase of a study designed to assess the ability of fecal microbial transplant to help children with autism. We know that there’s an aggressive disturbance of the gut bacteria in autism and we know that autism is characterized by inflammation. Dr. Emery Meyer at UCLA has discovered that changing the gut bacteria of a group of women has changed the way they perceived the world around them. And this is just scratching the surface.
Diet is an often overwhelming decision that people face every meal of every day. What are some simple guidelines people can use to maintain a healthy microbiome through their diet?
It’s important to get back to foods that are rich in prebiotic fiber—which is a unique type of fiber. Foods like jicama, Mexican yam, asparagus, dandelion greens, garlic and onions are foods that contain high levels of a particular type of prebiotic fiber that’s called inulin. Inulin is really helpful in terms of nurturing good gut bacteria. Our healthy gut populations use prebiotic fiber such as inulin to multiply and to increase their metabolism, and facilitate the creation of amino acids, the provision of vitamins, the reduction of gut permeability, and therefore inflammation.
They even facilitate the creation of serotonin and dopamine. The gut has a huge role to play in terms of that activity. So, prebiotic foods are very important to bring to the diet. Also, foods that are enriched with bacteria. That sounds distasteful, but these are foods that are fermented. Foods like kimchee, kombucha, cultured yogurt, sauerkraut, fermented meats, fermented vegetables; these are foods that are teeming with good, probiotic bacteria that have been long part of the human diet.
The types of food choices that threaten the bacteria are foods low in fiber, high in simple sugars, and foods that contain artificial sweeteners. Artificial sweeteners are very threatening to the gut bacteria, and change the gut bacteria in such a way as to favor obesity. Think about that.
Do we know why that is?
We’ve puzzled over this for a number of years, but we now know why. Why is it that people who stop drinking sugar-sweetened beverages and opt for artificial sweeteners suddenly gain more weight and dramatically increase their risk of becoming diabetic? It turns out that the changes that are imparted in gut bacteria by aspartame and other artificial sweeteners are changes that favor obesity, inflammation and metabolic change associated with diabetes. As a result, artificial sweeteners compromise metabolism, resulting in the body extracting more and more calories from foods.
What do you think about the growing movement to optimize diet through powdered food replacements and supplements?
I think we should eat food and not food replacements. While there are some decent food supplements out there that people can use when they travel or don’t have access to a really good source of organic, nutrient dense foods, my vote is to opt for complexity. Foods offer up the best benefit in their natural state. Juicing is very popular these days, and while you are getting a great dosage of vitamins and nutrients and mineral, you’ve thrown away the fiber. That being said, there is a very powerful role for probiotics as a supplement because people really aren’t consuming the levels of fermented foods that they need, nor are they getting enough prebiotic fiber. It’s been estimated the average American consumes about 5g a day of prebiotic fiber in comparison to our Paleolithic ancestors, who may have consumed as much as 135g in a single day. In that regard, sources of prebiotic fiber—such as acacia gum, which is really common at the health food store—makes sense.
How do you welcome back to the plate prebiotic food, probiotic enriched foods, and really get your arms around the fact that other foods you may be eating are threatening your microbiome? By and large, I think we should look for foods that aren’t packaged, which don’t have a list of ingredients. You don’t find a list of ingredients on a carrot, which is a good thing.
What are some interesting startups in the microbiome space?
One particularly interesting one is a startup at MIT called OpenBiome. It is doing some incredible work in providing fecal microbial transplant material to more than 150 hospitals here in America, and is also cataloging the genetics of the human microbiome in a large number of individuals and harvesting this data, which I think is going to be incredibly valuable moving forward.
Is there anything else you’d like to add?
We’re in the early stage. From an interventional perspective, who knows where the therapies will come from, and how they’ll be directed. I think what we’ll see in the next five to 10 years will be a greater interest in this science on the part of pharmaceutical companies looking to develop specific strains of bacteria that can be instilled into the human microbiome, into the colon that will have specific activities that will be remedial for certain disease processes. To me, this information is on par with the germ theory in terms of how big of a deal it is. I think the furthest reach has been the brain, as we now realize the brain is intimately related to what’s going on in the gut. It’s a very exciting time, and I’m looking forward to the future in a very big way.
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