The term dysbiosis refers to an imbalance between the levels of “good” bacteria and “bad” bacteria residing in your gut.
As having a healthy population of beneficial gut microbes is essential for proper digestion and metabolism of food, and a fully functioning immune system, it should come as no surprise that a state of dysbiosis can have some severe health implications.
Recent research has pointed to a dysbiosis of the gut flora as playing a significant role in the development of numerous degenerative diseases including metabolic syndrome, obesity and related inflammatory illnesses such as CVD, Type II Diabetes and Non-Alcoholic Fatty Liver Disease (NAFLD), autoimmune conditions and allergies, certain forms of cancer, and osteoporosis.1
Let’s take a look at each area in a little more detail:
Metabolic Syndrome, Obesity, Chronic Inflammation, and Autoimmune Diseases and Allergies
This may seem like a large list of unrelated diseases, but further investigation indicates that they may well all be linked, with dysbiosis as a major underlying factor.
Metabolic Syndrome and its associated conditions, including, but not limited to overweight/obesity, CVD/CHD, Type II Diabetes, and NAFLD, are the scourge of modern society. The patholgohy of metabolic syndrome is incredibly complex, with many different factors contributing to the condition. What has become clear, however, is that at its route, metabolic syndrome is a disease of inflammation.
Beneficial bacteria are known to affect inflammation in two main ways:
>By modulating the immune systems inflammatory response
>By maintaining the tight junctions in the gut, and preventing the passage of pro-inflammatory agents (pathogens/undigested food particles/etc) into the blood stream.
It is not surprising therefore that scientists have found strong correlations between dysbiosis and chronic inflammation and metabolic syndrome.2
Analysis of the microbiomes of obese humans have shown them to have different gut flora populations than normal weight, healthy humans, and individuals with dysbiosis have been shown to have significantly more pro-inflammatory markers than those with healthy gut flora. Studies in mice and rats have produced changes in bodyweight and fat storage by transplanting gut microbiota from one animal to another, and also significantly affected their risk of, and rate at which they develop, inflammatory conditions such as atherosclerosis.3
More recently there have been some small scale intervention studies on the effects of feeding probiotics and prebiotics to obese individuals, which have shown both decreases in body fat, and increases in satiety. Admittedly, the weight-loss in both studies was extremely modest (an average of just over 1kg over 12 weeks in both studies), but bearing in mind there were no other dietary interventions or calorie restriction, this is pretty impressive!45
As with metabolic syndrome, autoimmune diseases (such as arthritis, IBD, MS, lupus etc) and allergies (such as asthma and hay-fever) have been shown to be extremely complex, with many factors playing a role ranging from diet and genetics through to latitude and lifestyle. All these conditions are becoming increasingly more common, and there is a strong correlation between their occurrence and metabolic syndrome.
It appears that in genetically susceptible individuals with dysbiosis, the breakdown of the intestines’ barrier function (known as leaky gut) and subsequent passing of undigested proteins into the blood stream can cause not only chronic inflammation, but also cause the body to mistakenly mount an immune response against its own tissues. Although more human studies are needed, early research has been very promising, and studies in mice have been able to switch various autoimmune conditions on and off by removing/introducing specific strains of bacteria!678
Cancer
There is a strong correlation between dysbiosis, and certain kinds of cancer, most notably colon cancer. It is thought that certain types of “bad bacteria” may produce carcinogenic metabolites. “Good bacteria” on the other hand may well break down carcinogens ingested in food or from the environment and actually protect us from cancer.1
Osteoporosis
Osteoperosis has traditionally been attributed to a combination of mineral deficiencies in the diet combined with a lack of load bearing activities. More recent findings indicate that yet again the microbiome plays a role.
Firstly, we are reliant on our gut flora to extract calcium and other vital micro-nutrients from our food. It doesn’t matter how much calcium you consume, if you don’t have the right gut flora, none of it will be absorbed.
Secondly, inflammation has been found to play a major role in the development of the disease; the bones not only lack the necessary minerals for renewal, but are actively broken down.9
It is not only degenerative diseases that can be affected by our microbiome, however, in next week’s installment we shall be looking at the role of dysbiosis in infectious disease, and asking whether the use of antibiotics could be seriously damaging for your health?
1. Gut microbiota: next frontier in understanding human health and development of biotherapeutics
Satya Prakash, Laetitia Rodes, Michael Coussa-Charley, and Catherine Tomaro-Duchesneau
2. Gut Microbiota and Inflammation
Asa Hakansson and Goran Molin
3. Management of metabolic syndrome through probiotic and prebiotic interventions
Rashmi H. Mallappa, Namita Rokana, Raj Kumar Duary, Harsh Panwar, Virender Kumar Batish, and Sunita Grover
Parnell JA, Reimer RA.
Kadooka Y, Sato M, Imaizumi K, Ogawa A, Ikuyama K, Akai Y, Okano M, Kagoshima M, Tsuchida T.
6. Autoimmunity’s collateral damage: Gut microbiota strikes ‘back’
Daniel J Cua & Jonathan P Sherlock
7. Diet, gut microbiota and immune responses
Kendle M Maslowski & Charles R Mackay
8. Microbiota and Autoimmune Disease: The Hosted Self
Diane Mathis & Christophe Benoist
9. Chronic inflammatory intestinal diseases and bone loss
M T Bardella, M L Bianchi, and A Teti
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