As the workshop progressed, participants began exploring the social and policy challenges, especially around regulation of food claims, to translating all of these new research findings into tools and products for building and maintaining health. Chapter 6 summarizes those presentations and discussions (i.e., session 6). Finally, Chapter 7 summarizes the discussion that took place during the final session of the workshop, when participants were challenged to identify opportunities for future research and product development related to diet-mediated interactions between the microbiome and human health.


Microbial cells that populate the human body outnumber human cells by an order of magnitude, with the most densely populated areas being the nasal, oral, skin, gastrointestinal, and urogenital environments. Scientists are only just beginning to understand what these microbes do, how they function, and how they can be manipulated to benefit human health. Research on the human microbiome has benefited tremendously from other recent advances in microbiology, not the least of which is a growing recognition of the vast microbial diversity that exists. Keynote speaker Karen Nelson mentioned Craig Venter and colleagues’ circumnavigations of the globe to collect seawater samples and study oceanic microbial diversity (Rusch et al., 2007; Venter et al., 2004; Wu et al., 2011; Yooseph et al., 2007). According to Nelson, that work led to a doubling of the number of predictive protein signatures2 “essentially overnight.” The lesson learned, she said, was “that there is a tremendous amount of microbial diversity in the environment that we have not tapped … we really don’t know how much diversity is out there.”

Advances in Sequencing Technologies

In addition to spawning a realization of how vast the microbial world is, studies of microbial diversity in other (non–human body) environments also helped the development of advanced sequencing technologies that are now driving research on the microbiome. Nelson recalled how exciting it was when she and colleagues (Eckburg et al., 2005) used Sanger sequencing of the 16S ribosomal RNA (rRNA) gene to evaluate microbial diversity in six major subdivisions of the GI tract even though they were unable to interpret the significance of their results at the time. Shortly thereafter,


1 This section summarizes Karen Nelson’s keynote presentation.

2 Nucleotide sequence signatures that indicate the presence of a particular protein.

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