Inside the digestive system is a rainforest of rich microbiota that help to process nutrients, protect us from infection, maintain protective barriers in the gut, trigger the immune system, and even communicate with the brain.
To get a sense of how bacteria does this, first understand that microbes are everywhere. They live in the soil, in water, on our skin, and inside our bodies. These tiny organisms outnumber our own cells by a ratio of 10 to one and research suggests that the human genome has incorporated bits of DNA from the genes of various microbes. There are an estimated 500,000 metabolites in our blood derived from the microbiome.
The immune system, in particular, is largely dependent upon bacteria. Without microbes, we wouldn’t have developed the fully formed immune system we have today. It starts shortly after birth when microbiota begin to colonize the body through mucosal surfaces such as the lungs, mouth, or surface of the eyes. Children born by c-section tend to be colonized by hospital bacteria rather than their mother’s microbiome through vaginal contact. It is known that autoimmune diseases are more common in children born by c-section in hospitals.
Most of these microbes live in the gut and form the microbiome. And most of the changes that occur here have to do with shifts in the relative abundance of microbes already living in our guts. Trouble happens when a shift leads to ‘dysbiosis’ or a microbial imbalance that results in a disease state. “Control the bacteria of the gut, you control the immune system,” Dr. Kasper of Dartmouth's Geisel School of Medicine stated at the 30th annual Consortium of MS Centers conference at National Harbor, MD.
Diet is a critical factor in maintaining normal gut homeostasis or equilibrium. In fact, the food we eat helps to feed the microbiome in our body, and different microbes flourish when provided with different nutrients. So it’s easy to imagine that both long-term and short-term changes in diet can lead to microbiome shifts that may increase a person’s susceptibility to diseases. This can be seen in the rise of autoimmune diseases in Asia as the eastern diet and lifestyle have become more westernized.
Meanwhile, David et al (2014) demonstrated how short-term dietary changes affect the gut microbiome. Researchers compared the effects of a ‘plant-based diet’ rich in grains, legumes, fruits, and vegetables to an ‘animal-based diet’ comprised of meats, eggs, and cheese in 11 healthy volunteers who dramatically altered their diets for 3 days. The plant-based diet was associated with a more balanced immunological status while the animal-based diet increased bacteria linked to cardiovascular disease.
Diet can also create direct changes in gut microbial composition by promoting pro-inflammatory and anti-inflammatory responses, which in turn can produce changes in the immune system. This is done through food’s ability to affect intestinal permeability, as in the case of “leaky gut syndrome.” It can also affect metabolism through effects on endocrine system and dietary habits.
For example, certain elements in one’s diet, such as omega-3 fatty acids, aryl hydrocarbon receptors (AhR ligands), and tryptophan produced by gut microbes, produce an anti-inflammatory effect primarily through the induction of regulatory cells. Takata et al (2015) found that the ingestion of dietary yeast reduced the number of Th17 cells, suppressed interleukin (IL)-6 production, and increased Tregs in experimental autoimmune encephalomyelitis (EAE), a mouse-model of MS. Each of these may reduce MS-related disease activity.
Research is just beginning to unravel the influence of dietary factors on cell metabolism and gut microbiota, and subsequently, their potential effects on MS. Recently, Riccio and Rossano (2015) demonstrated that, in principle, pro-inflammatory food upregulates the biosynthetic and inflammatory pathways, whereas anti-inflammatory food upregulates oxidative metabolism and downregulates inflammation. This suggests that an appropriate nutritional intervention may improve the course of MS and may even work as a complementary treatment for the disease.
However, while there are foods that protect against inflammation, there are also foods that promote inflammation, so it is important to eat a balanced heart-healthy diet. The traditional Mediterranean diet, based on the consumption of extra-virgin olive oil, unrefined cereals, legumes, diverse vegetables and fruits, dairy products in moderation, fish and fishery products and low consumption of animal fat and meat, is likely one of the best approaches to staying healthy with MS.
See more helpful information:
David LA, Maurice CF, Carmody RN, et al. Diet rapidly and reproducibly alters the human gut microbiome, Nature. 2014 Jan 23; 505(7484): 559–563. Published online 2013 Dec 11.doi: 10.1038/nature12820.
Joscelyn J and Kasper LH. Digesting the emerging role for the gut microbiome in central nervous system demyelination. Mult Scler. 2014 Oct;20(12):1553-9. doi: 10.1177/1352458514541579. Epub 2014 Jul 28.
Riccio P and Rossano R. Nutrition Facts in Multiple Sclerosis. ASN Neuro. 2015 Feb 18;7(1). pii: 1759091414568185. doi: 10.1177/1759091414568185. Print 2015 Jan-Feb.
Takata K, Tomita T, Okuno T, et al. Dietary Yeasts Reduce Inflammation in Central Nerve System via Microflora. Ann Clin Transl Neurol. 2015 Jan; 2(1): 56–66. Published online 2014 Dec 3. doi: 10.1002/acn3.153.
Wu GD, Chen J, Hoffmann C, et al. Linking Long-Term Dietary Patterns with Gut Microbial Enterotypes. Science. 2011 Oct 7;334(6052):105-8. doi: 10.1126/science.1208344. Epub 2011 Sep 1.