1. THE HUMAN SUPRAORGANISM
In addition to the complex system of many functions represented by every human being there are up to 100 times more functions that bacteria are responsible for not only inside but also on the surface of each human being. The symbiosis between our body cells and our bacteria facilitates important health-maintaining functions i.e. the defense mechanism against contaminants, triggering of healing processes, production of essential vitamins or the regulation of appetite and hunger. The microbiota composition in adults is very diverse and stable. Depending on lifestyle and needs the bacterial composition will adapt appropriately. It is still unclear which and how many bacteria a healthy person should have, how big the variations may be in each individual and what changes are normal signs of aging. But it is already evident that intestinal bacteria can be controlled significantly thru diet and the lifestyle.
Fig. 1: The bacterial composition, also known as diversity, changes over a lifetime. The decrease of diversity in older people is associated with an increase of chronic inflammation and a decrease in mobility and vitality.
Another major area of research, Neurogastroenterology, is currently engaged in the interaction of gut bacteria and the brain. With messengers and stimulation of nerve pathways bacteria in the gut can actively manage metabolic processes in the brain; metabolic processes that go far beyond the influence of food intake or digestive.
Meanwhile, many diseases are associated with an altered microbiota composition. Examples include food intolerances, disorders of the immune system, stress responses, Alzheimer’s disease, autism and depression.
“You’re as young as you feel.” And this feeling of youth apparently has something to do with the distribution of gut bacteria influencing the positive physical ability up to old age. A study conducted by Paul O’Toole in Cork in Ireland in 2012 showed that people who move into assisted living do have a severe loss of the variety of intestinal bacteria during the first year. The species which they loose vary severly between individuals. Based on that the microbiota of two elderly people may be more different from each other than those of two younger persons. People who still live in old age, have a similar diverse microbiota as younger people. The loss of biodiversity of bacteria goes hand in hand witha synchronized loss of mobility, increased inflammation and other diseases.
There is a controversial discussion whether the intestinal bacteria change thru aging per se, or whether the age-related effects alter the composition of the intestinal bacteria. A change in lifestyle and a change in eating habits are the main causes. The immune system is constantly stimulated by the many depleting substances of bacteria. Bacteria in the digestive system function also as the first protection against invading pathogens. The gut with its bacterial colonization is our largest immune generating organ ,and it seems to be feasible that a change in this organ entails a change in the overall quality of life.
Fig.2: influence of genetics and environment on the aging process in humans.
(Reference: Boehm et al., 2013, Bioessays)
6. Stool pH