Recent Advances In Nutritional Sciences: An Overview Of Glycans And MiRNAs

Abstract

There are many nutritional substances that humans consume on a daily basis: water, carbohydrates lipids and proteins are main biochemical components of food. But others in a smaller amount are vitamins minerals and enzymes. At a possibly lesser quantity are glycans and miRNAs. The presence of oligoglycans in all food sources has been an established fact for many years. These special carbohydrates are present as glycoconjugates (glycoproteins or glycolipids) in and on the surface of all the cells (glycocalyx) of all organisms that we eat and remain intact through the GI tract as we lack the enzymatic repertoire of the human body to unbind their particular β-linkages. Glycans bind to naturally present human lectins (through protein-carbohydrate interactions), but also with other human glycans (through carbohydrate-carbohydrate interactions, or CCI). Moreover, these glycans, like fibres, are digested by the gut microbiota that resides within the intestine. As our biochemistry shapes the composition of the microbiome, so does the composition of glycans and foods that we consume, triggering biological responses. miRNAs are small, single-stranded, 19-to 23-nucleotide-long RNA molecules and affect the stability of messenger RNA (mRNA) influencing protein synthesis. miRNAs are also present in foods and act on both the microbial composition in our gut and may be absorbed by the walls of the GI tract, demonstrating resistance to food processing and enzymatic attack. Though still a topic of controversy, these small, noncoding RNAs that control gene expression may directly enter into the circulating miRNA population of dietary exogenous miRNAs. It can hence be possible to identify a relationship between glycans and miRNAs in food on one side, microbiota composition on the other and the resultant health status of the host (immune system), on the third side.

Blood Type Diets (BTD) and Aging: An Overview

“…Nevertheless, it is reported that there's a lack of evidence supporting the BTD hypothesis [18]. To date, only one serious mechanistic explanation, apart from the lectin hypothesis, has been put forward for BTD and involves the intervention of glycans [11]. Their presence in food and their particular biochemistry make them exceptionally prone to interact with human biomolecules and elicit and modulate immune and/or inflammatory responses [11,[19][20][21][22].…”

“…To date, only one serious mechanistic explanation, apart from the lectin hypothesis, has been put forward for BTD and involves the intervention of glycans [11]. Their presence in food and their particular biochemistry make them exceptionally prone to interact with human biomolecules and elicit and modulate immune and/or inflammatory responses [11,[19][20][21][22]. Ultimately, these processes of inflammation and immune tolerance could be regarded as possible underlying initiators of aging and age-related diseases [23,24].…”

“…Further types of fibre include prebiotics, such as inulin and oligofructose (also called fructooligosaccharides (FOS)) galactooligosaccharides (GOS), and the human milk oligosaccharides (HMO) [84,85]. These special carbohydrates, too, can manifest properties not unlike those displayed by the food glycans previously discussed [11].…”

“…The discrimination between self and nonself (on the basis of glycan determinants) can be accomplished by AGAs and GBPs of the innate immune system [79]. But this depends on what is recognized as self therefore essentially on what resembles the ubiquitous HBGA [11].…”

“…Hence, it can be stated that the proteosome and the nucleosome are no match for the glycome, as the coding capacity of the oligosaccharide language is simply orders of magnitude higher [10]. Only recently these ubiquitous molecules have been considered in nutrition and have been associated with many factors linking food components to health or disease [11]. Given the recent advances in glycobiology and glycochemistry, it is about time that nutritional sciences incorporate such tiny sweet molecules as fundamental constituents of the nutritional environment [12].…”