Lest we forget:
The de novo pathway to NAD+ starts in the gut with Tryptophan. The levels of which decrease with age due to gut bacteria imbalances
Minireview: Gut Microbiota: The Neglected Endocrine Organ
Manipulating the microbial composition of the gastrointestinal tract modulates plasma concentrations of tryptophan, an essential amino acid and precursor to serotonin, a key neurotransmitter within both the enteric and central nervous systems. Indirectly and through as yet unknown mechanisms, the gut microbiota exerts control over the hypothalamic-pituitary-adrenal axis. This is clear from studies on animals raised in a germ-free environment, who show exaggerated responses to psychological stress, which normalizes after monocolonization by certain bacterial species including Bifidobacterium infantis.
http://press.endocri...10/me.2014-1108
Metabolic Signatures of Extreme Longevity in Northern Italian Centenarians Reveal a Complex Remodeling of Lipids, Amino Acids, and Gut Microbiota Metabolism
With increasing age...profiling of blood serum displayed a marked decrease in tryptophan concentration, while an unique alteration of specific glycerophospholipids and sphingolipids are seen in the longevity phenotype. ... we also revealed that the longevity process deeply affects the structure and composition of the human gut microbiota ... a complex remodeling of lipid, amino acid metabolism, and of gut microbiota functionality are key regulatory processes marking exceptional longevity in humans.
http://journals.plos...al.pone.0056564
Functional metagenomic profiling of intestinal microbiome in extreme ageing
Among these, we observed an age-related increased abundance of genes involved in the tryptophan metabolism pathway (ko00380). This evidence is in agreement with the reduction of tryptophan found in serum of centenarians [22], although we cannot directly infer causality. Linking together the two observations, we advance the hypothesis that the potential increase of consumption of tryptophan by the gut microbiota affects its bioavailability within the host. A recent study showed patients with inflammatory diseases to have a significant depletion of serum levels of tryptophan compared to control population [23] and Huang et al. demonstrated a clear relationship between reduced serum tryptophan levels and an increase of immune activation [24]. In addition, the decrease of the serum level of tryptophan was associated with cognitive deficit in senile dementias [25-27], and Noristani et al. demonstrated that high triptophan diet lead to a reduction of the plaque pathology in Alzheimer's disease in mouse [28]. It is thus tempting to speculate that a microbiota-dependent reduction of tryptophan can nurture inflammaging in centenarians and could worsen the conditions of the patients affected by cognitive deficit.
http://www.impactagi...ull/100623.html
Also don't forget the increase in NF-kB etc with the increasing gut permeability that accompanies aging.
http://www.longecity...g-in-zebrafish/
Everybody! To the tune of Yellow Submarine! Sing after me: "We all live on bacteria shit! ...Bacteria shit! ...bacteria shit! ..."
Edited by Logic, 24 February 2016 - 07:52 PM.