Even though the human gut is diverse with individual guts having vastly different compositions, there are issues which can arise: pathogenic organisms can intrude, useful bacteria can be killed off by antibiotics, a normally beneficial species of bacteria may be too dominant. Any of these conditions, when it leads to a pathogenic state, is known as dysbiosis (Hawrelak JA & Myers, SP, 2004), and such conditions have been indicated to be associated with a number of illnesses. It may not be surprising that an unhealthy gut microbiome is connected to gastrointestinal illnesses like IBS and colon cancer, and dysbiosis has indeed been linked with these conditions (Casén et al. 2015, McFadden et al. 2015). But there are other less obvious issues related to gut microbiome dysbiosis (GMBD). These more obscure connections make sense based on the knowledge of the gut-brain axis and just how interconnected the human GMB is with our metabolic pathways. Health issues related to GMBD include type I and type II diabetes, as well as neurological conditions like MS and Alzheimer’s.
Both type I and type II diabetes, while different conditions, have been associated with GMBD. First, “microbial immunostimulation may beneficially affect the maturation of the postnatal immune system and protect against type-1 diabetes (Sanz 2015).” GMBD, including diet induced GMBD, may also play a role in inflation linked to insulin resistance and type II diabetes (Ibid). Still, diabetes is fairly closely related to diet and so it may not be that shocking. What is more astonishing is the connection between GMBD and neurological conditions like MS and Alzheimer’s. The connection between gut dysbiosis and conditions like MS make sense based on the connection between the GMB and the immune system. Two species which have been associated MS are Akkermansia muciniphila and Acinetobacter calcoaceticus. These microbes seem to “regulate T lymphocyte-mediated adaptive immune responses and contribute to the proinflammatory environment in vitro and in vivo (Cekanaviciute et al. 2017).”
It appears that GMBD, characterized either by general shifts in diversity or abundance of particular species, is associated with conditions ranging from gastrointestinal disorders like IBS, to neurological disorders like MS and Alzheimer’s. However, just because dysbiosis is associated with negative health outcomes does not mean that dysbiosis is the cause. It may just be a symptom. There are a few studies which seem to indicate that GMBD is at least partially responsible and not just a byproduct of these conditions. However causative relationship between dysbiosis and negative health outcomes is indicated by a failure for certain treatments, which seem to be effective in the presence of a healthy gut microbiome, to provide benefits in cases of dysbiosis.
Turmeric is a close relative of ginger. The inside of the tuber is bright orange with a flavor half way between a carrot and ginger. It is used extensively in Indian food, giving curry powder a distinctive yellow color. An active component of turmeric is curcumin (“Turmeric,” 2017). McFadden et al. (2015) looked at the potential for curcumin use in the prevention of colon cancer. The data failed to indicate a direct effect which could explain why curcumin was helpful, but was consistent with curcumin improving “bacterial richness, prevent[ing] age-related decrease in alpha diversity, increas[ing] the relative abundance of Lactobacillales, and decreas[ing] Coriobacterales order” (McFadden et al. 2015). Curcumin is not the only herbal supplement which seems to have an indirect effect through the GMB. Capsaicin, the phytoactive component found in chili peppers, responsible for the sensation of heat, seems to protect against low-grade inflation associated with obesity induced by high-fat diet, but only does so through interactions with gut microbiota like butyrate producing Ruminococcacaeae and Lanchnospiraceae, while reducing the population of “the lipopolysaccharide (LPS)-producing family S24_7” (Kang et al. 2017). Dietary allicin, one of the active components in garlic, seems to inhibit gut microbiota from converting L-carnitine into trimethylamine, a precursor to trimethylamine N-oxide, a chemical which increases the risk of arteriosclerosis (Wu et al. 2015).
With at least some justification for a causative relationship between GMBD and various illnesses established, the next question to ask is how to fix the problem. While probiotics, and foods containing probiotic bacteria such as yogurt are often used to treat minor dysbiosis (McFarland 2014), there are other treatments which may be useful depending on the severity of the dysbiosis and the difficulty in establishing a healthy gut microbiome. As mentioned earlier, curcumin seems to useful in preventing colon cancer, but does so by treating dysbiosis. Therefore aside from probiotics, curcumin may useful in repairing issues with the GMB. Similarly, the results by Kang et al. (2017) and Wu et al. (2015) suggest that capsaicin and allicin supplements may be able to provide some benefit in modulating the GMB. However, if treatments like probiotics, curcumin, capsaicin, and allicin do not provide enough of an effect, FMT is an extreme method for treating GMBD. Primarily, FMT is being used to treat C. difficile colitis, and the process involves using a colonoscope to deliver fecal material from a healthy individual to the unhealthy individual’s gut (Day, J. A., 2017, April 26).