The human microbiome also known as the human microbiota, include up to 1,000 different species of bacteria in the gut, is the focus of research in the fight against obesity for several research projects.
The human microbiome is the sum total of all the microorganisms, that inhabit our bodies, the majority are beneficial, the good, normal microbiota, and others not so good. They include bacteria, fungi, archaea, eukaryote, and viruses. From the top of our scalp to the bottom of our feet, outside and inside of our body, these the cells of these tiny organism have adapted to the variety of environments (moist, dry, dark, etc.). The bacteria cells in the gut, estimated at 500 to 1,000 different species and much smaller than human cells, and thought to out number our own human cells by a factor of 10:1. A component of the immune system, the beneficial microorganisms help maintain a balance between the good and the bad by assisting in the fight against harmful germs and other organisms by “revving up or dampening down our immune system.” Some of the beneficial microorganisms have their own arsenal of antibiotics and are thought to play a role in developing or educating our immune cells in identifying and eliminating harmful organisms.
We get our own unique mix of microbiome, from our parents, in breast milk and from the exposure to the environment, especially in our early years. Our microbiome tend to stay with us the majority of our life unless altered by factors including, but not limited to, invading microbes, antibiotics, excessive use of antimicrobial chemicals like hand sanitizer, infections, our diet, environmental pollutants, or lifestyle. Alternating the microbiome could either improve ones health or, as is often the case, contribute to allergies, sickness or disease.
Extensive research has been made into microbiomes both by independent researchers and on a global scale through such projects as the Human Microbiome Project (HMP) is the United States. An initiative by the National Institutes of Health, the project is designed to identify and characterizing the microorganisms which are found in both healthy and diseased humans. Other global projects looking beyond just the human microbione include The Earth Microbiome Project (EMP), and The Brazilian Microbiome Project (BMP).
Not everyone’s microbiome is the same. In fact different microbiota may perform the same function in different people. For instance, the specific microbiota or total mix microbiome that are responsible for digestion of carbohydrates in one individual may be different from the microbiota or mix of microbiome that perform the same function in another individual. This suggests that if a person has a specific disease or condition, it could be the result of more than just one microbe being altered in one person or it could be from a combination of microbes in another person.
Microbiota have another function and one that has led to the investigation of the largest habitat of the most complex and diverse microbiota in the body … the digestive system. This function is to regulate how much energy a person burns and the storage of fat, in other words … our metabolism. This investigation includes research into the connection between microbiota and body weight.
Research has found that the microbiota of the digestive system in lean individuals is different than that of the digestive system of overweight individuals. A review of one body of work that looked at a study of humans and one of mice both of whom underwent gastric by-pass surgery, postulated that 20% of the weight loss was from a change in the microbiota. Even more compelling was the finding that when the microbiota from mice who had underwent this change in microbiota was introduced into mice that had no gut microbiota, both groups of mice loss weight and had less fat than the control mice.
Another study found that when given microbes from an obese human, mice became obese. Findings also showed that there are fattening microbes and thinning microbes and that the thinning microbes can overtake the fattening microbes when mice ate a diet that was high in fruits and vegetables and low in saturated fat.
The findings of a study from the Netherlands by Nathalie M Delzenne, Audrey M Neyrinck, and Patrice D Cani, reported on two bacteria associated with obesity and thinness. Bacteroidetes bacteria were found to be more common in lean people while Firmicutes bacteria were more common in the obese people. However when the obese people consumed a low calorie diet for a year, “as they lost weight, they acquired Bacteroidetes and lost Firmicutes.” Of additional interest was the finding that when overfeeding both lean and obese individuals the “bacteria in the obese people didn’t change, but for the lean people their Firmicutes increased and their Bacteroidetes decreased. As the Firmicutes increased so did the absorption of calories eaten.