Current Nutrition & Food Science - Volume 9, Issue 2, 2013

A high dietary intake of fruits and vegetables is associated with a reduced disease risk. The fruits and vegetables contain fibers, vitamins, phytosterols, sulfur compounds, carotenoids, and organic acids, which all provide beneficial effects on health, but they also contain a variety of polyphenols. Recently, polyphenols have received considerable attention because of their various physiological effects, including anti-oxidative, anti-inflammatory and anti-carcinogenic effects. In addition, experimental evidence demonstrates that some polyphenols participate in regulation of intestinal tight junction (TJ) barrier. The TJ, a multiple-protein complex, regulates the paracellular permeability between the epithelial cells and the dysfunction is implicated with the pathogenesis of intestinal and systemic diseases. Among polyphenols investigated, quercetin, kaempferol, myricetin, morin, hesperetin, naringenin and daidzein have been reported to enhance the basal TJ integrity in intestinal cells. In most cases, the enhancements are accompanied by increases in the expression and/or cytoskeletal association of TJ proteins, such as occludin, claudins and zonula occludens. Genistein, epigallocatechin- 3-gallate and curcumin present protective effects on the TJ integrity against harmful substances, such as oxidative stress and pro-inflammatory cytokines. Chrysin increases the intestinal permeability through decreased expression and cytoskeletal association of TJ proteins. Based on these evidences, the regulation of intestinal TJ barrier by polyphenols could be therapeutic and preventive approaches for intestinal barrier defect-associated diseases.

Postnatal maturation of the intestinal barrier occurs coincident with increasing enteral feeding. Normal intestinal bacterial colonization is established once enteral feeding is achieved. Colonization of intestinal microflora plays a vital role in the regulation and maintenance of intestinal barrier function. As the important end products of intestinal microbial fermentation of mainly undigested dietary carbohydrates in the intestinal lumen, short chain fatty acids (SCFAs) may mediate the regulatory effect of normal intestinal microflora on intestinal barrier function, especially the colonic mucosal barrier. During physiological conditions, the production of SCFAs in the bowel is very important for energy salvage and crucial for gastrointestinal adaptation and maturation. Multiple mechanisms may be involved in the regulation of the intestinal barrier by SCFAs. It is also possible that, excessive concentrations of SCFAs may be toxic and cause disruption of the intestinal barrier. Once the intestinal barrier is disrupted, the inflammatory cascade may be activated, which can induce further injury to the intestinal mucosa. Therefore it has been hypothesized that overproduction/accumulation of SCFAs in the intestinal lumen may play a pivotal role in the pathogenesis of neonatal necrotizing enterocolitis (NEC). While we may use probiotics for the prophylaxis of NEC in premature infants, we should be very cautious when considering the use of oligosaccharides (as prebiotics) in formulas for premature infants.

Probiotics are beneficial bacteria present in various dietary components and many of these colonize in the human and animal intestine. In the gut probiotics help the host by assisting in maintenance of normal mucosal homeostasis. Probiotics not only help maintain normal function of the gut mucosa, but also protect mucosa from injurious factors such as toxins, allergens and pathogens. The beneficial effect of probiotics is mediated by multiple mechanisms, including cytoprotection, cell proliferation, cell migration, resistance to apoptosis, synthesis of proteins and gene expression. One of the important cytoprotective effects of probiotics in the intestinal mucosa is to strengthen the epithelial tight junctions and preservation of mucosal barrier function. Probiotics not only enhance barrier function by inducing synthesis and assembly of tight junction proteins, but also by preventing disruption of tight junctions by injurious factors. Bioactive factors released by probiotics trigger activation of various cell signaling pathways that lead to strengthening of tight junctions and the barrier function. This article reviews and summarizes the current understanding of various probiotics that are involved in the protection of gut barrier function, highlights the cellular and molecular mechanisms involved in the protective effect and addresses the clinical implications of probiotic supplementation.

Gut barrier integrity is important to maintain homeostasis between intraluminal contents and the sterile internal environment. Several physical and immunological mechanisms exist to support this balance. An inflammatory response may disrupt this delicate balance in the intestine and lead to intestinal barrier failure. Ingestion of dietary lipids in high concentrations has been shown to preserve intestinal barrier integrity. Several physiological responses are elicited upon ingestion of a high-fat diet that may account for these beneficial effects. Chylomicrons are formed that can neutralize endotoxin via apolipoproteins. Furthermore, ingestion of long chain polyunsaturated fatty acids decreases production of inflammatory mediators and the expression of adhesion molecules. Next to these direct effects, dietary lipids also trigger a newly discovered neuro-immunological pathway via release of cholecystokinin (CCK). Release of CCK triggers the autonomic nervous system leading to a reduction of the inflammatory response and preservation of intestinal barrier integrity via binding of acetylcholine to specific nicotinic receptors. The inflammatory response and intestinal barrier dysfunction play an important role in a number of intestinal disorders such as inflammatory bowel disease and postoperative ileus. Manipulation of the inflammatory response and intestinal barrier integrity via administration of lipid enriched nutrition may provide a new therapeutic opportunity to reduce clinical relevant disorders such as postoperative ileus. In this review we discuss the interaction between lipid enriched nutrition, the autonomic nervous system, inflammation and the intestinal epithelial barrier.

Modern Western food contains less than twenty per cent of the ingredients on which our paleolithic ancestors lived and other primates like the wild chimpanzees live today. Fresh greens, fruits, seeds, piths, bark and insects were the foods to which humans had been adapted during millions of years. A recent study found that 80% of diet of wild chimpanzee consists of ripe and unripe fruits, young leaves, flowers and fresh and dry seeds, and roots/tubers used only in times of draft. In contrast Western food consists of more than fifty per cent refined carbohydrates (cooked, rice heated to very high temperatures, bread, pasta, potato and other tubers) and in another 25-30 per cent animal products and refined oils, leaving less than 20 per cent of their foods similar to those of our ancestors. The situation is even worse in critically ill patient, whose nutrition usually contains no greens at all. It is fully documented that these Western foods, when consumed in larger quantities are detrimental to health: inducing increased systemic inflammation; increased supply of and stimulation of IGF1, stimulation of Toll-like receptors, leading to obesity and an epidemic of chronic diseases, which has increased and continue to increase dramatically. Modern molecular biology techniques have made it possible to explore the mechanisms behind these catastrophic effects of modern living. It is a 50-year-old observation that beneficial bacteria like lactobacilli do not grow well when exposed to food ingredients such casein (dairy) and gluten (wheat, rye and barley). More recent Studies demonstrate that human microbiota and its functions compared to rural minorities, are more than 90 % reduced in Western individuals, and further reduced by exposure to chemicals, including pharmaceuticals. The ultimate consequence of these changes is that body membranes lose their tightness and start leaking; such leakage often documented for all body membranes; effects observed in barriers such as in the gut, airways, skin, oral cavity, vagina, nose, eye cavity, placenta and blood-brain barrier. The consequence of this is leakage over the membranes of various damaging toxins of microbial origin such as endotoxins, but also food-derived proteotoxins such as casein, gluten and zein and toxins producing by heating foods to high temperature (grilling, roasting, baking etc) and production of glycated and lipoxidated molecules (AGEs and ALEs). Furthermore, bacterial debris and whole dead or live bacteria will leak and found in the fat of obese and the plaques of individuals with arteriosclerosis. Recent studies report not only reduced numbers and diversity of bacteria in microbiota of individuals with various diseases, but also totally different microbial species in individuals with obesity and various diseases. Attempts to treat diseases by supplying probiotics have only been partly, and at the best temporarily, successful, when applied without any changes in food habits. Furthermore, probiotics are not compatible with pharmacological and other toxic chemicals. Eco-biological treatments, with plant-derived substances, or phytochemicals, e.g. curcumin and resveratrol, and pre-, pro- and synbiotics offer similar effects as use of drugs referred to asbiologicals, although milder but also without adverse effects. Such treatments should be tried as alternative therapies; mainly, to begin with, for disease prevention but also in early cases of chronic diseases. Dramatic alterations, in direction of a paleolithic-like lifestyle and food habits, appear, as we see it today, the only alternative to control the present escalating global health crisis.

Simulated frying studies were carried out by frying circular sheets of rice flour dough in rice bran oil, heated to 180±2°C. The total frying time was up to 8 hrs. At the end of every 2 hrs, the oil samples were drawn and physicochemical changes were determined. Results showed that the changes were markedly rapid in the initial phase of frying which is first the 2 hrs. The Lovibond colour values for 0 to 2 hrs were from 12.1±0.5 to 43.1±0.95. During the same period, peroxide value (PV), free fatty acid (FFA), anisidine value (AV), total polar material (TPM), saturated fatty acid (SFA), monounsaturated fatty acids (MUFA) and viscosity were found to increase from 0.2±0.01 to 3.5±0.05 Meq.O2/kg, 0.25±0.05 to 0.69±0.05%, 5.0±0.05 to 11.1±0.2, 1.0±0.05 to 1.9±0.05%, 25.6±0.05 to 26.2±0.05 %, 43.7±0.01 to 43.9±0.05 % and 107±0.01 to 108±0.2 mPas, respectively. Beyond 2 hr, a gradual increase in these parameters was observed till the end of frying. Similarly, more than 50 % of the tocopherol present was lost at the end of 2 hr of frying. Marginal decrease was observed in oryzanol content from 1.6±0.05 to 1.4 ±0.05 % polyunsaturated fatty acids (PUFA) 30.5±0.01 to 28.6±0.05 % and iodine values from 100.2±0.05 to 96.8±0.05 even after 8 hr of frying.

Seabuckthorn is a rich source of nutrients and bioactive components beneficial for human health. Fruit juice is rich in sugar, organic acids, amino acids, essential fatty acids, phytosterol, flavonoids, vitamins and mineral elements. There are 24 minerals and 18 kinds of free amino acids in seabuckthorn juice. The total quantity of phytosterol in seabuckhtorn exceeds soybean oil by 4-20 times. Seabuckthorn seed is a source of valuable oil characterized by high oleic acid content and one to one ratio of omega-3 and omega-6 fatty acids. The oil absorbs ultraviolet light and promotes healthy skin. The leaves contain many nutrients and bioactive substances such as carotenoids, free and esterified sterols, triterpenols, and isoprenols. Seabuckthorn has been used in traditional system of medicine for centuries. Beneficial effects of seabuckthorn on human health have been extensively investigated and substantiated by studies, suggesting a great potential of the plant for maintaining and promoting human health. Recent research has supported and extended the traditional uses of the plant for treatment of various diseases. The unique and valuable characteristics of seabuckthorn shrub serve as a storehouse for researchers in the field of biotechnology, nutraceutical, pharmaceutical, cosmetic and environmental sciences. Traditional usage coupled with commercial value and modern scientific research has immense scope to benefit the modern society from the lesser known shrub.