There has been a plethora of interest in the human microbiome as of late. In fact, barely a week ago, a new study was published, which showed that mice who drank water (laced with huger-suppressing bacteria) ate less, had lower body fat, and staved off diabetes – even when consuming a poor diet.1 This is just the latest of many potential breakthroughs made in the last few years in regards to the microbiome. Though this breakthrough is specific to obesity, there are many unique and diverse links made to the types of bacteria found within our gut.2, 3, 4, 5, 6, 7, 8
Interestingly, another recent study discussed the link between the lifestyles of indigenous populations, and their gut health.9 Researchers found the microbial populations among various hunter-gatherers were markedly similar – and drastically different than those who live a more modern way of life.10, 11, 12, 13 This supports the observation that human microbiomes are actively involved in health, and that subsequent changes from living more sanitized, industrialized lifestyles, has led to increased likelihood of autoimmune disorders.14, 15, 16 This is yet another way in which our Paleolithic ancestors had it right.17, 18
It has taken the scientific community some time to come around to the realization that obesity is correlated with an alteration in the gut microbiome.19, 20 Two classes of bacteria (bacteroides and firmacutes) are important here, with firmacutes bacteria being very prevalent in those whom are obese.21, 22, 23 But, it turns out not all the data supports firmacutes being the only factor. The main focus, instead, as far as mechanism goes, is the formation of increased amounts of metabolic endotoxins.24, 25 These metabolic endotoxins are more specifically, deoxycholic acid and lipopolysaccharides (LPS).26, 27
A Paleo diet promotes improved gut health, whereas the Western diet is a large source of problems, for the microbiome.28, 29 Interestingly, we see the duality of evidence here, in that (observationally) hunter-gatherers display much better microbial profiles.30 But, we also have specific mechanistic evidence, which shows exactly how poor gut health translates into obesity. This is a clear-cut example that the Western diet (quite literally) makes us sick – and fat.
So, what can one do, if looking to optimize their microbiome? Many will state that a probiotic is absolutely necessary, and there is no other way to improve your ratio of beneficial microbiota. This is simply not the case. Quite obviously, you should eat a nutrient-dense, protein and antioxidant packed diet. A Paleo diet is beneficial for a myriad of reasons, but including fermented foods (like sauerkraut) regularly, will result in a vastly improved ratio of good bacteria to bad bacteria. Without any extra supplementation required!
And, this improved ratio is a significant shield against obesity, as evidenced by salient scientific literature. This optimal ratio of specific types of microbes is simply something that a Western diet is not capable of achieving. If you needed one more reason to consume a delicious Paleo diet, the emerging link between gut health and obesity, is definitely one of the best reasons. Go home, enjoy a glass of kombucha or dig into a bowl of sauerkraut, and take comfort in the fact that you are helping to nurture your microbiome – so you may stay lean and healthy for a long time to come.
 Chen Z, Guo L, Zhang Y, et al. Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity. J Clin Invest. 2014;124(8):3391-406.
 Le chatelier E, Nielsen T, Qin J, et al. Richness of human gut microbiome correlates with metabolic markers. Nature. 2013;500(7464):541-6.
 Parekh PJ, Arusi E, Vinik AI, Johnson DA. The role and influence of gut microbiota in pathogenesis and management of obesity and metabolic syndrome. Front Endocrinol (Lausanne). 2014;5:47.
 Vrieze A, Van Nood E, Holleman F, Salojärvi J, Kootte RS, Bartelsman JF, et al. Transfer of intestinal microbiota from lean donors increases insulin sensitivity in individuals with metabolic syndrome. Gastroenterology (2012) 143(4):913.
 Borody TJ, Khoruts A. Fecal microbiota transplantation and emerging applications. Nat Rev Gastroenterol Hepatol (2012) 9(2):88–96.
 Kadooka Y, Sato M, Imaizumi K, Ogawa A, Ikuyama K, Akai Y, et al. Regulation of abdominal adiposity by probiotics (Lactobacillus gasseri SBT2055) in adults with obese tendencies in a randomized controlled trial. Eur J Clin Nutr (2010) 64(6):636–43.
 Everard A, Lazarevic V, Derrien M, Girard M, Muccioli GG, Neyrinck AM, et al. Responses of gut microbiota and glucose and lipid metabolism to prebiotics in genetic obese and diet-induced leptin-resistant mice. Diabetes (2011) 60(11):2775–86.
 Romijn JA, Corssmit EP, Havekes LM, Pijl H. Gut-brain axis. Curr Opin Clin Nutr Metab Care. 2008;11(4):518-21.
 Obregon-tito AJ, Tito RY, Metcalf J, et al. Subsistence strategies in traditional societies distinguish gut microbiomes. Nat Commun. 2015;6:6505.
 Brown K, Decoffe D, Molcan E, Gibson DL. Diet-induced dysbiosis of the intestinal microbiota and the effects on immunity and disease. Nutrients. 2012;4(8):1095-119.
 Eckburg P.B., Bik E.M., Bernstein C.N., Purdom E., Dethlefsen L., Sargent M., Gill S.R., Nelson K.E., Relman D.A. Diversity of the human intestinal microbial flora. Science. 2005;308:1635–1638.
 Proctor L.M. The human microbiome project in 2011 and beyond. Cell Host Microbe. 2011;10:287–291.
 Dethlefsen L., McFall-Ngai M., Relman D.A. An ecological and evolutionary perspective on human-microbe mutualism and disease. Nature. 2007;449:811–818.
 Campbell AW. Autoimmunity and the gut. Autoimmune Dis. 2014;2014:152428.
 Okada H, Kuhn C, Feillet H, Bach JF. The ‘hygiene hypothesis’ for autoimmune and allergic diseases: an update. Clin Exp Immunol. 2010;160(1):1-9.
 Konkel L. The environment within: exploring the role of the gut microbiome in health and disease. Environ Health Perspect. 2013;121(9):A276-81.
 Ley R.E., Hamady M., Lozupone C., Turnbaugh P.J., Ramey R.R., Bircher J.S., Schlegel M.L., Tucker T.A., Schrenzel M.D., Knight R., et al. Evolution of mammals and their gut microbes. Science. 2008;320:1647–1651.
 Tappenden K.A., Deutsch A.S. The physiological relevance of the intestinal microbiota—Contributions to human health. J. Am. Coll. Nutr. 2007;26:679S–683S.
 Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006;444(7122):1027-31.
 Tsai F, Coyle WJ. The microbiome and obesity: is obesity linked to our gut flora?. Curr Gastroenterol Rep. 2009;11(4):307-13.
 Abdallah ismail N, Ragab SH, Abd elbaky A, Shoeib AR, Alhosary Y, Fekry D. Frequency of Firmicutes and Bacteroidetes in gut microbiota in obese and normal weight Egyptian children and adults. Arch Med Sci. 2011;7(3):501-7.
 Kallus SJ, Brandt LJ. The intestinal microbiota and obesity. J Clin Gastroenterol. 2012;46(1):16-24.
 Bradlow HL. Obesity and the gut microbiome: pathophysiological aspects. Horm Mol Biol Clin Investig. 2014;17(1):53-61.
 Tilg H, Kaser A. Gut microbiome, obesity, and metabolic dysfunction. J Clin Invest. 2011;121(6):2126-32.
 Cani PD, Amar J, Iglesias MA, et al. Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes. 2007;56(7):1761-72.
 Yoshimoto S, Loo TM, Atarashi K, et al. Obesity-induced gut microbial metabolite promotes liver cancer through senescence secretome. Nature. 2013;499(7456):97-101.
 Trøseid M, Nestvold TK, Rudi K, Thoresen H, Nielsen EW, Lappegård KT. Plasma lipopolysaccharide is closely associated with glycemic control and abdominal obesity: evidence from bariatric surgery. Diabetes Care. 2013;36(11):3627-32.
 Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI. The effect of diet on the human gut microbiome: a metagenomic analysis in humanized gnotobiotic mice. Sci Transl Med. 2009;1(6):6ra14.
 De filippo C, Cavalieri D, Di paola M, et al. Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. Proc Natl Acad Sci USA. 2010;107(33):14691-6.
 Schnorr SL, Candela M, Rampelli S, et al. Gut microbiome of the Hadza hunter-gatherers. Nat Commun. 2014;5:3654.