It’s a terrific illustration of the co-dependence of bacteria and humans, a symbiotic relationship that benefits both: Bacteria rely on us to provide them with nutrients, especially prebiotic fibers, while many species of bowel flora produce B vitamins that humans require for survival and health.
Because humans are incapable of synthesizing most B vitamins (niacin is an exception, as it can be manufactured from tryptophan by humans), we rely on dietary intake and bacterial production to provide them to us. Bacterial production is looking more and more like a substantial source of most B vitamins, nutrients we require for many purposes that include energy production. (Bacteria mostly produce B vitamins for the benefit of each other, non-B vitamin-producing species relying on the B vitamins produced by a B-vitamin producer. But we also benefit from this activity.)
Several probiotic bacterial species are avid producers of B vitamins niacin, thiamine, riboflavin, folate, pantothenic acid, vitamins B6 and B12. Among the microbial species that have been identified as producers of B vitamins are:
- Lactobacillus rhamnosus GG, Lactobacillus plantarum CRL 1973 and several other species/strains, especially vigorous producers of folate
- Streptococcus thermophilus TH982 and M17PTZA496, vigorous producers of folate
- Lactobacillus reuteri CRL1098 produces vitamin B12
- Lactobacillus casei synthesizes folate
- Lactobacillus fermenti synthesizes thiamine
- E. coli produces pantothenate, B6, and biotin
- Numerous species of Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria produce riboflavin
- Bifidobacterium longum ATCC 15697 produces riboflavin
- Most Bacteroidetes and Fusobacteria species produce thiamine
B vitamins are not the only nutrients provided to the host (us) by microbes, as microbial conversion of vitamin K1 to K2 is another. (The apparent need for K2 may therefore better reflect dysbiosis and reduction or loss of K1-to-K2 converting species, not necessarily just a lack of dietary intake of foods sourced from grass-fed animals or specific fermented foods. However, charting the full range of microbial species capable of vitamin K conversion and how to restore them in the human microbiome is still a work in progress.)
My point in all this? I am raising the question: Could the apparent need for vitamin B supplementation really simply reflect dysbiosis, i.e., disruption of the species that were meant to be substantial sources of B vitamins? Could the need for folate in pregnant mothers reflect both poor diet and dysbiosis and taking exogenous folic acid be nothing more than a temporary workaround while not addressing the real cause? And is a better way to obtain B vitamins is to cultivate healthy bowel flora, rather than take a B-50, B-100, or other B-complex?
The conversation on cultivation of the human microbiome is evolving. Nobody wants to micromanage their microbiome and have to, say, take 10 different probiotic preparations in order to obtain all the species that are beneficial. I believe that we are heading towards an understanding of the microbiome in which we restore a handful, say, 6, 10, or 12, of what I call “foundational” species and strains that, once restored, provide the environment hospitable to other beneficial species and, by their presence and metabolic activity, cultivate dozens or hundreds of other probiotic species without your further involvement. Akkermansia muciniphilia, for example, may be among these foundational species. The greater the Akkermansia population (up to a point), the more beneficial Lactobacilli and Bifidobacteria species thrive.
In the meantime, I predict that many widely-held notions on nutrition and health are going give way to more sophisticated insights into the microbiome making, for instance, B vitamin supplementation a thing of the past for most of us.