There exists a fair-sized research community whose members think about extending healthy human life by manipulating the long term operation of metabolism. They are looking at small and incremental gains, however, and don't expect success in their work over the next ten to twenty years to go much beyond providing a few additional years of life and generally better health throughout life. This will be achieved through ways of mimicking calorie restriction or other life-extending genetic and epigenetic alterations discovered in mice. This is a far cry from the quality and quantity of life extension we'd expect to emerge from a mature SENS technology base, focused on repair of the low-level biological damage that causes aging, but it is the focus of the mainstream - much as we'd like that to be different.
In this world of incremental advances and manipulation of metabolism, researchers are becoming increasingly aware that they cannot ignore the vast population of symbiotic bacteria we carry with us throughout our lives. You can look back in the Fight Aging! archives to see that evidence has emerged in recent years to support the idea that changes in gut bacteria may be significant for long-term health:
The intestinal microbiota is important for maintenance of host health, providing energy, nutrients and protection against invading organisms. Although the colonic microbiota is relatively stable throughout adult life, age-related changes in the gastrointestinal (GI) tract, as well as changes in diet and host immune system reactivity, inevitably affect population composition. Recent studies indicate shifts in the composition of the intestinal microbiota, which may lead to detrimental effects for the elderly host.
Here is a more recent paper on the same topic, entitled "Gut microbiota as a candidate for lifespan extension", which looks toward turning understanding into action:
On the basis of recent knowledge in worms, flies, and humans, an important role of the gut microbiota in aging and longevity is emerging. The complex bacterial community that populates the gut and that represents an evolutionary adapted ecosystem correlated with nutrition appears to limit the accumulation of pathobionts and infections in all taxa, being able of affecting the efficiency of the host immune system and exerting systemic metabolic effects.
There is an urgent need to disentangle the underpinning molecular mechanisms, which could shed light on the basic mechanisms of aging in an ecological perspective. Thus, it appears possible to extend healthy aging and lifespan by targeting the host as a metaorganism by manipulating the complex symbiotic ecosystem of gut microbiota, as well as other possible ecosystems of the body.
I think we'll be seeing more of this line of thinking in the years ahead - it hasn't been greatly explored and there's an increasing level of interest in slowing aging through metabolic manipulation. This fits right in to that research community and its interests.