Resistant Maltodextrin Suppresses Intestinal Phenols Production by Modifying the Intestinal Environment.

Protein is an essential nutrient that plays several roles in the maintenance of the human body. A high-protein diet is also known to play an important role in weight management in obese individuals and in maintaining muscle strength in the elderly. However, over-consumption of protein can have negative effects on health, including deterioration of the intestinal environment by the production of amino acid metabolites such as phenols. Interest in the regulation of the intestinal environment to maintain health has gained attention recently. Resistant maltodextrin (RMD) is a prebiotic dietary fiber. Therefore, we investigated whether RMD suppressed the production of amino acid metabolites through intestinal regulation in rats. Wistar rats were fed either an AIN-93G diet or a modified AIN-93G diet containing 5% tyrosine. RMD (2.5% or 5.0%) was provided with drinking water. The rats were fed these diets and water ad libitum for 3 wk. Urine was collected overnight, after which serum, liver, kidneys, and the whole cecum were collected from rats under anesthesia with isoflurane for analysis of phenols and microbiota. RMD decreased the cecal, serum, and urinary levels of phenols, especially phenol. Moreover, the relative abundance of intestinal Romboutsia ilealis showed a significant correlation with the cecal phenols levels, and RMD decreased the abundance of this species. Thus, RMD may suppress phenols production and decrease serum phenols levels by altering the intestinal environment in rats.

Visceral Fat-Reducing Effect and Safety of Continuous Consumption of Beverage Containing Resistant Maltodextrin: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Clinical Trial.

Obesity is regarded as a global concern with increasing prevalence, most notably in developed countries. Metabolic syndrome is a predictor of cardiovascular disease and type 2 diabetes mellitus and is defined as the accumulation of multiple risk factors caused by abdominal visceral obesity. Resistant maltodextrin (RMD) is a soluble dietary fiber that has been shown to reduce visceral fat in long-term clinical trials when continuously administered at 10 g, three times daily. Herein, we evaluated the effects of long-term consumption of 5 g RMD three times daily. A total of 140 healthy adults were randomly assigned to two intervention groups for a 12-wk randomized, double-blind, placebo-controlled, parallel-group trial. Participants ingested a test beverage containing 5 g RMD or a placebo beverage without RMD. Interviews, anthropometric measurements, physiological examination, blood tests, and urinalyses were conducted at baseline and every 4 wk during the trial. Computed tomography scans were performed at baseline and at the end of week 8 and 12. Results showed that abdominal visceral fat area (VFA) significantly decreased in the test group from 105.33±26.83 cm2 at baseline to 101.15±24.33 cm2 at week 12. Further, a significant difference was observed in the VFA between the test and control groups (p<0.05), confirming the function of continuous RMD consumption in reducing abdominal visceral fat. Furthermore, neither serious adverse events nor adverse clinical findings were observed in the blood or urine tests following consumption of RMD, suggesting that continuous consumption of RMD containing beverages is safe.

Tandem Cation/Anion Exchange SPE Cartridge Method for Sample Desalting for HPLC Analysis of Soluble Dietary Fiber: Development and Inter-laboratory Validation.

In HPLC analyses of soluble dietary fiber, desalting processes using open, mixed-bed ion-exchange columns are time-consuming and labor-intensive. We developed and validated a simple desalting method using tandem cation/anion exchange SPE cartridges. We found that combining Bond Elut Jr SCX (upstream) and Bond Elut PSA (downstream) cartridges provided adequate desalting of test solutions. The developed method was then validated in an inter-laboratory study. Five test samples were prepared by mixing food matrixes with purified soluble dietary fiber and treated to generate solutions to test the desalting process. These solutions were then analyzed by eight different laboratories. The results demonstrated that the developed method is simple and reliable for desalting samples containing 140 to 945 mg/100 mL of soluble dietary fiber in preparation for HPLC analysis of soluble dietary fiber.

Energy value evaluation of hydrogenated resistant maltodextrin.

Hydrogenated resistant maltodextrin (H-RMD) is a dietary fiber whose energy value has not previously been reported. We evaluated the energy value of H-RMD. We conducted an in vitro digestion test, in vivo blood glucose measurement after ingestion, in vitro fermentability test, excretion test by rats and indirect calorimetry combined with breath hydrogen measurement for humans. H-RMD was hydrolyzed in vitro in a very small amount by human salivary amylase and by the rat small intestinal mucosal enzyme. Ingestion of H-RMD did not increase the blood glucose level of human subjects. An examination of in vitro fermentability suggested that H-RMD was fermented by several enterobacteria. Oral administration of H-RMD showed a saccharide excretion ratio of 42% by rats. A combination of indirect calorimetry and breath hydrogen measurement evaluated the metabolizable energy of H-RMD as 1.1 kcal/g in humans. We concluded from these results that H-RMD was not digested or absorbed in the upper gastrointestinal tract and was fermented in the colon to produce short-chain fatty acids which provided a lower amount of energy than that of resistant maltodextrin.

Comprehensive measurement of total nondigestible carbohydrates in foods by enzymatic-gravimetric method and liquid chromatography.

Total nondigestible carbohydrate (NDC) in foods was determined by combining, not modifications, AOAC Official Methods 991.43, 2001.03, and 2002.02. Total NDC included insoluble dietary fiber (IDF) + high-molecular-weight soluble dietary fiber (HMWSDF), nondigestible oligosaccharides (NDO) not precipitated in ethanol solution, and resistant starch (RS). Eight sources of NDC (cellulose, wheat bran, gum arabic, resistant maltodextrin, polydextrose, fructooligosaccharide, galactooligosaccharides, and RS) were incorporated in different combinations into standard formula bread samples. All of the NDC sources and bread samples were analyzed for their (1) IDF + HMWSDF content with corrections for residual RS amount using AOAC Official Method 991.43, (2) NDO by liquid chromatography (LC) in AOAC Official Method 2001.03, and (3) RS by AOAC Official Method 2002.02. The correlation coefficient (R(2)) comparing calculated amounts versus measured amounts of total NDC in 11 bread samples was 0.92. Analysis of commercial food samples was also well matched with the DF + NDO value on their nutritional label. Consequently, we confirmed a single measurement of LC can determine all NDO in foods, and total NDC in foods can be determined by unifying existing AOAC Official Methods.