Understanding the Relationship Between Gut Health & Overall Health

Understanding the Relationship Between Gut Health & Overall Health

The human microbiome is, in and of itself, a complex ecosystem;1 it is a “microbial organ” within the gastrointestinal tract.2 The intestinal microbiome is dominated by anaerobic bacteria and includes approximately 500-1,000 species whose collective genomes are estimated to contain 100 times more genes than our own human genome.3 When the intestinal ecology is altered, so too is host health; studies show that the maintenance of a healthy microbiome is inseparable from host health.1 These microbes influence physiological function (particularly metabolism), local mucosal homeostasis, inflammation, and immunity.1,4

Recent research suggests that healthy lifestyle factors including a diversified diet, limited use of processed foods, avoidance of prolonged restricted diets, and consumption of adequate dietary fiber all promote a healthy microbiome.1 Studies have shown that seafood, including marine seaweeds and invertebrates, are rich in dietary fibers and can help maintain symbiosis in the gut.5 Other research suggests that gut microbiota alterations due to unhealthy lifestyle factors and inadequate nutrition may contribute to the pathogenesis of a broad spectrum of diseases such as obesity, diabetes mellitus, non-alcoholic fatty liver disease,3 colorectal cancer, cardiovascular disease, Parkinson’s disease, Alzheimer’s disease, and type 2 diabetes.5

Alterations to the gut microbiota start at the earliest stages of life; in infancy, disruption of the developing microbiota can contribute to the risk of immune and metabolic disease as an adult.1 At the other end of the age spectrum, in a large study of the elderly, reduction of microbial diversity was associated with a shift toward a monotonous diet; the loss of diversity was also linked with increased markers of inflammation and frailty.6

The good news is that the intestinal microbiome can be shaped by long-term dietary interventions, according to a 2015 study in obese patients.7 The study observed changes in the microbiota after one year of consumption of either a Mediterranean diet or a low-fat, high complex carbohydrate diet in an obese population. Results suggest that long-term consumption of both diets exerts a protective effect on the development of type 2 diabetes, due to an increasing abundance of Roseburia genus and F. prausnitzii, respectively.7

As a clinician, you can help your patients restore a healthy, diverse microbiome at any stage of their life. Learn more about the role of nutrition and the microbiome at IFM’s premier course, Applying Functional Medicine in Clinical Practice (AFMCP).



  1. Shanahan F, van Sinderen D, O’Toole PW, Stanton C. Feeding the microbiota: transducer of nutrient signals for the host. Gut. 2017;66(9):1709-1717. doi:1136/gutjnl-2017-313872.
  2. Okubo H, Nakatsu Y, Kushiyama A, et al. Gut microbiota as a therapeutic target for metabolic disorders. Curr Med Chem. 2018;25(9):984-1001. doi:2174/0929867324666171009121702.
  3. Backhed F, Ding H, Wang T, et al. The gut microbiota as an environmental factor that regulates fat storage. Proc Natl Acad Sci USA. 2004;101(44):15718-15723. doi:1073/pnas.0407076101.
  4. Cammarota G, Ianiro G. Gut microbiota and cancer patients: a broad-ranging relationship. Mayo Clin Proc. 2017;92(11):1605-1607. doi:1016/j.mayocp.2017.09.009.
  5. Shang Q, Jiang H, Cai C, Hao J, Li G, Yu G. Gut microbiota fermentation of marine polysaccharides and its effects on intestinal ecology: an overview. Carbohydr Polym. 2018;179:173-185. doi:1016/j.carbpol.2017.09.059.
  6. Claesson MJ, Jeffery IB, Conde S, et al. Gut microbiota composition correlates with diet and health in the elderly. Nature. 2012;488(7410):178-184. doi:1038/nature11319.
  7. Haro C, Montes-Borrego M, Rangel-Zuniga OA, et al. Two healthy diets modulate gut microbial community improving insulin sensitivity in a human obese population. J Clin Endocrinol Metab. 2016;101(1):233-242. doi:1210/jc.2015-3351.

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