Morphology, dipeptidases and disaccharidases of small intestinal mucosa in vitamin B 12 and folic acid deficiency

Fermented foods and gastrointestinal health: underlying mechanisms

Although fermentation probably originally developed as a means of preserving food substrates, many fermented foods (FFs), and components therein, are thought to have a beneficial effect on various aspects of human health, and gastrointestinal health in particular. It is important that any such perceived benefits are underpinned by rigorous scientific research to understand the associated mechanisms of action. Here, we review in vitro, ex vivo and in vivo studies that have provided insights into the ways in which the specific food components, including FF microorganisms and a variety of bioactives, can contribute to health-promoting activities. More specifically, we draw on representative examples of FFs to discuss the mechanisms through which functional components are produced or enriched during fermentation (such as bioactive peptides and exopolysaccharides), potentially toxic or harmful compounds (such as phytic acid, mycotoxins and lactose) are removed from the food substrate, and how the introduction of fermentation-associated live or dead microorganisms, or components thereof, to the gut can convey health benefits. These studies, combined with a deeper understanding of the microbial composition of a wider variety of modern and traditional FFs, can facilitate the future optimization of FFs, and associated microorganisms, to retain and maximize beneficial effects in the gut.

B Vitamins and Their Roles in Gut Health

B vitamins act as coenzymes in a myriad of cellular reactions. These include energy production, methyl donor generation, neurotransmitter synthesis, and immune functions. Due to the ubiquitous roles of these vitamins, their deficiencies significantly affect the host’s metabolism. Recently, novel roles of B vitamins in the homeostasis of gut microbial ecology and intestinal health continue to be unravelled. This review focuses on the functional roles and biosynthesis of B vitamins and how these vitamins influence the growth and proliferation of the gut microbiota. We have identified the gut bacteria that can produce vitamins, and their biosynthetic mechanisms are presented. The effects of B vitamin deficiencies on intestinal morphology, inflammation, and its effects on intestinal disorders are also discussed.

Severe impairment of dietary folate utilization in the elderly

Absorption of folates, vitamin B6, pantothenate, and riboflavin from a natural food source (yeast) and from synthetic folylmonoglutamate was studied in 24 elderly subjects (age range, 73 to 101 years) and in 12 healthy younger subjects (age range, 24 to 42 years). All subjects absorbed riboflavin, vitamin B6, and pantothenate from yeast. Ingested folypolyglutamates (the preponderant folates in yeast) proved to be a very poor source of folates for the elderly subjects, whereas synthetic folylmonoglutamate served as a good source. In the younger subjects, yeast was a significant folate source. It is suggested that the folate deficits so common in the elderly are caused by impaired ability to obtain folate from ingested foods. The resultant folate deficit may induce changes in the epithelial structure and enzyme secretion of the small bowel, which may further exacerbate folate malabsorption.