You’ve probably been hearing about the amazing community of tiny life forms that colonize our gastrointestinal tract. It’s called the “gut microbiome,” or often, “gut bacteria.” It is being hailed as one of the greatest discoveries in the past century. But what is it, and does it concern people with Parkinson’s disease (PD)?
The gut microbiome is an enormous community of friendly bacteria that live in our small and large intestines. They affect our immune system, feed on parts of food that we can’t digest, and help protect against some types of infection. The importance of our microbiome is only beginning to be understood.
In 2011, scientists studying mice found that stress could lower the kinds of good bacteria and increase harmful bacteria in the gut.1 PD can be stressful at times, so this can be of concern.
Researchers later learned there are two main families of bacteria in humans – the Bacteroides genus and the Prevotella genus. Vegetarians usually have more of the prevotella species, as it is associated with carbohydrates. Meat eaters usually have the bacteroides species; it is associated with protein and animal fat.2 Still later, scientists found that people with PD have very little of the Prevotella species, although the reason why, and the exact functions of the two species, are unknown so far.3
Researchers have noted the incidence of constipation, irritable bowel disease, small intestinal bacterial overgrowth, and increased intestinal permeability (leaky gut). They speculate that the brain-gut-microbiota axis may have a role in the origin and/or development of the disease. Mulak and Bonaz state:
“Dysregulation of the brain-gut-microbiota axis may significantly contribute to the pathogenesis of PD. The gut seems to play a critical role in the pathophysiology of PD representing a route of entry for a putative environmental factor to initiate the pathological process. The close relationship between gut dysbiosis, intestinal permeability and neurological dysfunction suggests that the gut microbiota modification may provide a promising therapeutic option in PD.4″
It is far too early to say exactly if or how poor health of the microbiome may cause PD or influence its progression. But we can be certain that the health of microbiome is important to everyone, and possibly more so for those with PD. There is good indication that – among other things – a healthy microbiome influences a healthy weight, helps control blood glucose, maintains immune function, may prevent inflammatory bowel disease, and stimulates neurons of the enteric nervous system that signal the brain. A weakened microbiome appears to have negative effects upon depression, anxiety, obesity, diabetes, and allergies. For information on the ongoing Human Microbiome Project, see: https://commonfund.nih.gov/hmp/index
How can we promote and maintain the good health of the microbiome?
We can support those friendly bacteria by feeding them prebiotic foods. Remember we said these bacteria feed on parts of food that we can’t digest? Those indigestible parts are fibers, on which the bacteria thrive. Different types of bacteria need different types of fiber, so consider eating a wide variety of fiber-rich foods.
Foods with prebiotic value
Asparagus, chicory root, jicama, Jerusalem artichokes (also known as “sunchokes”), dandelion greens, onions, garlic, leeks, burdock root, yacon root, bananas, and whole wheat contain inulin. Inulin is a type of fructooligosaccharide (FOS), that feeds the friendly bifidobacteria.
Green bananas are a good source of resistant starch, which feeds bacteria that produce a fatty acid called butyrate. Butyrate serves as food for the cells of the colon, helping to maintain colon health and prevent colon cancer. Resistant starch also helps lower blood glucose and increase insulin sensitivity, important for those with prediabetes and diabetes.
Apples have pectin, which also feeds colon cells that produce butyrate.
Flaxseeds have both soluble and insoluble fibers, from mucilage gums.These increase butyrate production, lignin, and cellulose.
Barley and oats are rich sources of fibers, including beta-glucan which lowers cholesterol levels.
Whole wheat fiber contains arabinoxylan oligosaccharides, which feed bifidobacteria.
Honey contains oligosaccharides that feed both bifidobacteria and lactobacilli.
Cocoa, and dark chocolate, also contain a type of fiber that is food for bifidobacteria and lactobacilli. Researchers speculate that a component of cocoa, phenylethylamine, may boost dopamine availability, though this remains to be proven.
Foods that contain probiotics
We can also support the microbiome community by eating foods that naturally contain the microorganisms. These are called “probiotic foods.” They have undergone fermentation, which promotes the growth of some of the same bacteria in our microbiome, and eating these foods helps to replenish them in our gut. It is important, though, to be certain they have not been pasteurized, cooked, or canned, as heat kills the living organisms.
Foods like sauerkraut, kimchee, tempeh, miso, yogurt, kombucha, kefir and pickled vegetables cured in a saltwater brine (not in vinegar), Gouda, Cheddar, and mozzarella cheeses, also some brands of cottage cheese.
Kefir is a very good probiotic-rich food, because it has many different kinds of probiotic bacteria.
NOTE: If you are using Azilect®, you should not eat aged and fermented foods, as they have high levels of tyramine. Such foods can cause hypertensive crisis. An exception is yogurt, which is safe for those using Azilect.® For more information on tyramine and foods see Managing Tyramine in Your Diet
Protect and support the microbiome
Antibiotics are important medications for fighting infections. However, they also destroy the living organisms in the microbiome.
• If you need to use an antibiotic, it will be especially important to also eat plenty of probiotic and prebiotic foods, or use a probiotic supplement. Look for a supplement that has millions of live cultures, and has many different strains of the bacteria, not just two or three strains.
• Avoid meat from animals that have been raised with antibiotics.
• Do not use antibacterial soap or hand sanitizers.
• Avoid highly-processed foods. Refined flour and sugar in these foods replace prebiotic fibers, and do not nourish the microbiome.
• Increase use of foods that are rich in fibers, as well as those that contain probiotics (people using Azilect® should not consume fermented foods, except for yogurt).
Although we don’t yet know the exact role of the microbiome with regard to Parkinson’s disease, we do know it plays a part. And we know that we need healthy gut microbes in order to stay well ourselves. For a healthy gut microbiome, avoid antibacterial products, animals raised on antibiotics, and highly-processed foods. If you need an antibiotic, increase use of probiotic foods and/or supplements to rebuild the gut bacteria.
And feed your microbiome with a variety of whole, fiber-rich foods. When you shop for food, or prepare a meal, ask yourself “How much of this is food for my gut bacteria?” If there is enough, your friendly microbes will stay well-nourished and will be your allies, helping to keep you in a constant state of good health.
1Bailey, M., Dowd, S.E., Galley, J.D., Hufnagle, A.R., Allen, R.G., Lyte, M., 2011.
Exposure to a social stressor alters the structure of the intestinal microbiota:
implications for stressor-induced immunomodulation. Brain Behav. Immun. 25,
2 Wu GD1, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA, Bewtra M, Knights D, Walters WA, Knight R, Sinha R, Gilroy E, Gupta K, Baldassano R, Nessel L, Li H, Bushman FD, Lewis JD. Linking long-term dietary patterns with gut microbial enterotypes. Science. 2011 Oct 7;334(6052):105-8.
3 Scheperjans F1, Aho V, Pereira PA, Koskinen K, Paulin L, Pekkonen E, Haapaniemi E, Kaakkola S, Eerola-Rautio J, Pohja M, Kinnunen E, Murros K, Auvinen P. Gut microbiota are related to Parkinson’s disease and clinical phenotype. Mov Disord. 2015 Mar;30(3):350-8. doi: 10.1002/mds.26069. Epub 2014 Dec 5.
4Mulak A, Bonaz B. Brain-gut-microbiota axis in Parkinson’s disease. World J Gastroenterol 2015; 21(37): 10609-10620.