Functional Roles of B‐Vitamins in the Gut and Gut Microbiome

When you see a list of the functions of the gut microbiota, "synthesis of B-vitamins" is usually prominent. But the metabolism of B-vitamins is enormously complex. This review article gets into the details: how some B-vitamins are absorbed in the small intestine; how excess B-vitamins make it down to the colon; how the gut microbiota in the colon synthesize additional B-vitamins; and how these synthesized B-vitamins have important functions, both for the host and for gut microbial ecology.

Impact of diet and the bacterial microbiome on the mucous barrier and immune disorders

In humans, good health depends (in part) on mucous. That is, the layer of mucous that lines the interior of the gut, which prevents microbes from leaking out of the gut and into systemic circulation, disrupting the functioning of the immune system. In fact, some major immune/metabolic conditions (obesity, diabetes, inflammatory bowel disease and others) are linked to this breakdown of the gut barrier. Here’s some reading on the relationship between the mucous barrier, diet, and gut microbiota -- including how a diet high in fat (at least, high in certain fats) makes the mucous barrier more permeable through alterations in gut microbiota.

Dietary Components, Microbial Metabolites and Human Health: Reading between the Lines

Ultimately, tracking the precise health effects of diet may come down to the metabolites produced by a person's gut microbiota. This nice review goes through different macronutrient substrates in the diet (everything from inulin to milk), specifying which metabolites they are associated with and what activity those metabolites are predicted to have. Then the authors zoom out to the metabolites associated with different dietary patterns: the Mediterranean diet, the paleo diet, and others.
 

Metabolic and functional interplay between gut microbiota and fat-soluble vitamins

Fat soluble vitamins -- A, D, E, and K -- are those that are absorbed when taken with a source of lipids, and are stored in the body for a longer period of time because they are kept in the body's fat and liver. This review covers what we know about fats, the gut microbiota, and fat soluble vitamins. The authors describe how all three of these components interact to influence immune function and gastrointestinal physiology.
 

Human milk oligosaccharides: Shaping the infant gut microbiota and supporting health

Human milk is full of complex carbohydrates called human milk oligosaccharides (HMOs) -- which have recently become available in some commercial infant formulas. This review paper details the effects of HMOs on the health of the infant, and what's known about the mechanisms. Scientists have found HMOs do not provide direct nutritional value to the infant; instead, they function as prebiotics, promoting the growth of beneficial bacteria in the infant gut and conferring some health effects indirectly.
 

Nutrition Support and the Gastrointestinal Microbiota: A Systematic Review

Clinically, you may have reasons to recommend either parenteral nutrition (PN) or enteral nutrition (EN) to your clients / patients. This systematic review looked at the effects of these two interventions on the gut microbiota, and found more deviation from the 'normal' state with PN compared to EN: that is, PN was associated with a lower diversity microbiota and higher Proteobacteria.

The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics

You may have heard the word "synbiotic" used to refer to a combination of a probiotic and a prebiotic. But this definition lacked scientific precision, making it difficult to know what evidence was necessary to prove that a synbiotic product conferred a health benefit. Hot off the press, check out the international scientific consensus definition of synbiotics, co-authored by a global panel of scientific experts. (Read the highlights, along with an infographic on the new definition, in this article from the International Scientific Association for Probiotics & Prebiotics.)