Inflammation, Obesity and Bacteria
Obesity has stolen national headlines as one of the most pressing health issues of our generation. It is clear that obesity is a multifactorial, complex process that spans genetics, culture, socioeconomic status, environment, beliefs, stress and more.
Many facets are well understood about obesity, particularly the consequences, which we know to be increased risk and incidence of heart disease and other chronic diseases, infertility, shortened life span and decreased productivity.
What about the aspects or angles of obesity that aren?t as well understood? Are there things that we can be doing in our everyday lives that can help us protect us from and treat obesity? There certainly are, and today we are going to take a little trip into your gastrointestinal system and learn about the connection between inflammation, your gut bacteria, and body composition.
When we think about inflammation, what is conjured up in many people?s mind is redness, heat, swelling and pain. This is the type of inflammation that occurs when we sprain our ankle.
The truth is, we have some level of normal, very low-grade inflammation going on all the time in the gut. This is part of how the immune system surveys and monitors the GI tract and offers no ill consequence.
In people who are carrying excessive fat, or who have an altered body composition, giving them a high percentage of body fat compared to their muscle and bone mass, this inflammation is kicked up a notch, out of the normal range.
There are several researchers that have teased out the inflammatory pathways and processes in obesity. Adipose tissue itself makes inflammatory compounds, so it makes sense that if we had a greater volume of fat mass, we would have a greater volume of inflammatory compounds too.
Yet there is something else going on as well. Part of this inflammatory process also comes from the gut flora ? those native bacteria that live in the gut.
The bacteria that live in our gut form an enormous colony that weighs roughly four pounds and is compromised of 500-1,000 types of bacteria, which them further represent thousands and thousands of unique strains. Interestingly, the have the same metabolic capacity as your liver, which means they are very busy indeed. Collectively they are known as the gut microbiota.
Your microbiota ? all four pounds of it ? serves dozens upon dozens of functions, most of them necessary for life. Among other things, your gut bacteria help you digest proteins and lactose, manufacture and assimilate B vitamins, vitamin K and flavonoids, create 5-10% of short chain fatty acids, which are in turn used as energy for the cells of the gastrointestinal tract, they help manufacture essential fatty acids and absorb minerals.
The bacteria also help regulate peristalsis, thus helping with constipation, diarrhea and IBS, they help balance the pH of the intestines, protect the teeth and gums, protect and treat antibiotic-associated diarrhea, help manufacture ?natural? antibiotics and antifungals ? thus helping reduce infection occurrence and also the duration of infection, including upper respiratory infections, bladder infections and yeast infections, they help ?cut up? by products of harmful bacteria, and help protect against and modulate autoimmune conditions.
Additionally, they help recycle and manufacture hormones, help children grow optimally, break down bile acids, reduce blood levels of ammonia and help promote optimal metabolism and weight.
Ah, we have circled back. People who are overweight and obese have a greater amount of inflammation than those of normal weight. In part this inflammation is derived from the fat cells themselves, and in part it is driven by the gut microbiota.
How? It seems clear at least that this has to do with disturbances in normal gut flora. What is unclear is what comes first ? the obesity or the disturbance in flora? We know from research that mice that are given antibiotics to simulate imbalances (also called gut dysbiosis) in their gut flora have increased inflammatory compounds and by-products of harmful bacteria in their gut and stools.
These disturbances in turn affect the mice?s ability to metabolize glucose and thus lead to increased body fat, weight gain, inflammation, increased damage from free radicals, which then leads to both metabolic syndrome and increased intestinal permeability, or leaky gut.
Dysbiosis, the presence of unfriendly bacteria in the gut, can also lead to inflammation directly. A class of bacteria known as ?gram negative? have compounds called lipopolysaccharides (LPS) in their cell walls, which trigger immediate inflammation that will turn chronic as long as LPS is present and the immune system remains stimulated. People who are overweight and obese have more of this evidence present in the stool and gut than their normal weight counterparts.
What is less clear in the research is exactly what strains of ?native? flora are involved. So, not the intrusive, LPS-bearing gram negative bacteria (this can get confusing because some of our normal flora is gram negative too), but the types of bacteria that make up the microbiota of people who are obese/overweight vs. people who are not.
We have learned that we have thousands upon thousands strains or species of bacteria that live in our gut. Species are classified under their genus, and genus are classified under family. Families are organized then under order, class, phylum and kingdom. This is how biologists and taxonomists organize living creatures. For example, a tiger belongs to the family Felidae, the genus Panthera and the species tigris.
The vast majority of bacteria that live in our gut, in fact, up to 90%, come from just two phyla: Bacteroidetes and Firmicutes. Researchers were able to assess that fat mice had more than half as many Bacteroidetes and twice as many Firmicutes and lean mice. They also found this in 12 people, who were then put on a low fat or a low carb diet for one year. Interestingly, their flora normalized as they lost weight, but these findings have not been able to be reliably replicated.
What this work has taught us is that instead of looking at enormous phyla of bacteria, we have to get more specifically into the species that we find. Enter Bifidobacterium species and Staph aureus. Here we see more agreement in the data. Multiple researchers (Kalliomaki, P.D. Cani, Delzenne, Isolauri) have noted that higher levels of Staph aureus are present in people who are obese, including children. Interestingly, S. aureus also triggers inflammation. Researchers have also noted that lean individuals have higher levels of Bifidobacter species, especially B. bifidum and B. breve.
Your gut microbiota ? those friendly bacteria that you have living in your gut ? have influence over hormonal metabolism, digestion, immunity and even your body composition.
Antibiotic use and overuse, small intestinal bacterial overgrowth, gut dysbiosis, food allergies, yeast infections and chronic digestive complaints can all throw the essential balance of your gut flora off, in turn contributing to the inflammatory process of obesity.
One of the easiest ways to make sure you have a good balance of healthy, beneficial bacteria in your gut is to eat a variety of fermented foods. Fermented dairy products like yogurt, kefir, aged hard cheeses and cultured cottage cheese are a good source of healthy bacteria, but people who are allergic to dairy or who don?t tolerate it well should not partake. There are a variety of other options to choose from, including sauerkraut, kimchi, amazake, Kombucha, kefir water, fermented soy such as miso, traditionally pickled vegetables, umeboshi plums, fresh sprouted grains and even wine! Note that some of these foods ? particularly miso and perhaps some pickles ? are high in sodium. Hard cheese and wine contain histamines, so people who are sensitive should use caution.
If you have all of your dietary and lifestyle factors in order, and underlying hormonal imbalances have been addressed, yet you are still experiencing fat loss resistance, it may be time to turn your attention to your gut.
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