Did you know that you are only 10% human? Yes, that’s right! Each one of us is a composite of 10% human and 90% microbe. On a cellular level, the gut bacteria outnumber human cells 10 to 1, while bacterial genes exceed the human genes by 150 times!
The bacterial community populating the gut (also known as gut microbiota) represents a complex, continuously evolving ecosystem. Its development begins at birth, when the baby’s gut gets colonized with bacterial species present in the birth canal, on mother’s skin, in the environment and the breast milk. It appears, that during the last trimester of pregnancy, the birth canal and maternal milk ducts get selectively populated with bacterial species particularly beneficial for the baby (e.g. Lactobacillus and Bifidobacterium).
The digestive tract of an adult harbours up to a 1000 different species. They are present in varying numbers and combinations in different individuals. In other words, human microbiotas are like fingerprints: no 2 sets are the same. The specific composition depends on the age, diet, lifestyle and environmental factors.
The impact of intestinal microbiota goes far beyond its well established role in digestive health. Gut bacteria affect how we harvest and store energy extracted from food, produce certain vitamins (e.g. K and some B vitamins), they protect us against external pathogens and help “educate” the immune system.
Due to its important roles in key physiological processes, gut microbiota is now considered a separate endocrine organ by some scientists and has become one of the most studied subjects in medical research over the last 5-7 years. Over this time, multiple links have been established between altered bacterial profiles and development of such health conditions as obesity, type 2 diabetes, heart disease, rheumatoid arthritis, depression and even Alzheimer’s.
In my next post I will look into the effect of gut bacteria on such metabolic disorders as obesity and diabetes.