The human gut has a staggering number of microbes in it – an estimated 3 times more than the cells in our body (100 trillion bacterial cells as compared to 30 trillion human cells). Despite the staggering number of microbes in and on the human body, very little is known about their roles in human health and disease. gut flora or gut microbiota as they are called are the microorganisms that live in our digestive tracts. This is also common in many animals, including insects. In humans, the gut microbiota has the largest numbers of bacteria and the greatest number of species compared to other areas of the body. Many of these have not yet been successfully cultured, identified, or otherwise characterized. In humans, the gut flora is established at one to two years after birth and keeps evolving throughout our lives.
The relationship between some gut flora and humans is not merely commensal (non-harmful coexistence), but rather a mutualistic relationship. Age, Diet, Geography, level of physical activity, use of antibiotics is known to influence the gut flora. It is a diverse ecosystem in and very important for our good health. The absence of some of these microbes leads to diseases and development of some conditions.
We know that the gut flora was important. Two recent studies show how important they are.
Autism-Spectrum Disorder (ASD) is characterised by repetitive, stereotypical and often restricted behaviour such as head-nodding, and by the difficulties those with it have in reading the emotions of, and communicating with, other people. These symptoms are noticeable in children from the age of two onwards. Currently, in America, about one child in 59 is diagnosed with ASD. What causes ASD has baffled psychiatrists and neurologists since the syndrome was first described, in the mid-20th century, by Hans Asperger and Leo Kanner. But the evidence is pointing towards the bacteria of the gut. That suggestion has been reinforced by two recently published studies—one on human beings and one on laboratory rodents.
Researchers Dr Krajmalnik-Brown and Dr Adams performed their study on 18 autistic children aged between seven and 16. Of their participants 15 were regarded, according to the Childhood Autism Rating Scale, as having “severe” autism. Their studies found that the guts of these kids had a notable absence of Prevotella, the bug, which makes its living by fermenting otherwise-indigestible carbohydrate polymers in dietary fibre. When they were given a dosage of this bacteria significant changes began to appear in the kids behaviour. Even 18 weeks after treatment started the children had begun showing reduced symptoms of autism. After two years, only three of them still rated as severe, while eight fell below the diagnostic cut-off point for asd altogether. These eight thus now count as normal. Also Bifidobacterium, had quadrupled in the kids guts. Bifidobacterium is what is known as a “probiotic” organism—something that acts as a keystone species in the alimentary ecosystem, keeping the mixture of gut bacteria healthy. This, says Dr Krajmalnik-Brown, suggests the children’s guts have become healthy environments that can recruit beneficial microbes by themselves.
Can your gut also give you a competitive advantage in athletics? Molecular biologist Jonathan Scheiman, first author of the study, were able to single out a specific group of bacteria, of the genus Veillonella, that was more abundant in the athlete’s gut after the 26.2-mile Boston marathon but not in 10 non-runners. The Veillonella bacteria use lactate as their main food source. During exercise, lactate is produced by the muscles and released into the bloodstream. It’s also responsible for the feeling of muscle burn. “We have a bug that responds to exercise and its natural function is to eat a metabolite that is associated with fatigue,” said Scheiman. The researchers next wondered if the Veillonella bacteria influenced running performance, so they isolated one strain, V. atypica, from one of the marathon runners and implanted it in the guts of mice. Animals with the critter ran 13 percent longer in a treadmill than control mice implanted with another type of bacteria, L. bulgaricus, that does not use lactate as food. Woods notes, however, that the test the researchers used is not representative of a marathon in humans.
Are we hindering the health of our gut by living in too sterile an environment and eating junk? A good “food for thought” for the weekend. Have a great one.
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