Beneficial effects of rice endosperm protein intake in Japanese men with risk factors for metabolic syndrome: a randomized, crossover clinical trial

The Effect of the Rice Endosperm Protein Hydrolysate on the Subjective Negative Mood Status in Healthy Humans: A Randomized, Double-Blind, and Placebo-Controlled Clinical Trial

The rice endosperm protein (REP) hydrolysate containing the following rice endosperm protein derived oligopeptides QQFLPEGQSQSQK, LPEGQSQSQK, and pEQFLPEGQSQSQK (a N-terminal pyroglutamate residue-modified peptide) reportedly showed an antidepressant-like effect in an animal model. We investigated the effect of the REP hydrolysate on healthy humans who self-reported mental fatigue with subjectively low vigor. Seventy-six participants (age: 20-64 years) were randomly allocated to two groups. The influence of the REP hydrolysate on the mood state was evaluated in two studies: single intake (Study 1) and repeated intake over 4 weeks (Study 2). A salivary stress marker, Chromogranin A (CgA), was measured in Study 1. The single intake of the REP hydrolysate significantly improved the Profile of Mood Status 2nd edition for adults (POMS 2) subscale of Tension-Anxiety. Additionally, the salivary CgA concentrations were remarkably reduced after the single intake of the REP hydrolysate. Though a single intake of the REP hydrolysate did not significantly influence the other subscales and the TMD of the POMS 2 and the Euthymia Scale, both the subjective and objective results supported the possible effect of the REP hydrolysate on reducing anxiety and nervousness. No significant positive effects on the subjective mood state (Euthymia Scale and POMS 2) and sleep quality (Insomnia Severity Index) were observed in the trial setting employed for Study 2. In conclusion, a single intake of REP hydrolysate might help relax the subjective feelings of tension and anxiety. The effectiveness of repeated REP hydrolysate intake needs to be tested in a different clinical setting.

Health Benefits of Cereal Grain- and Pulse-Derived Proteins

Pulses and whole grains are considered staple foods that provide a significant amount of calories, fibre and protein, making them key food sources in a nutritionally balanced diet. Additionally, pulses and whole grains contain many bioactive compounds such as dietary fibre, resistant starch, phenolic compounds and mono- and polyunsaturated fatty acids that are known to combat chronic disease. Notably, recent research has demonstrated that protein derived from pulse and whole grain sources contains bioactive peptides that also possess disease-fighting properties. Mechanisms of action include inhibition or alteration of enzyme activities, vasodilatation, modulation of lipid metabolism and gut microbiome and oxidative stress reduction. Consumer demand for plant-based proteins has skyrocketed primarily based on the perceived health benefits and lower carbon footprint of consuming foods from plant sources versus animal. Therefore, more research should be invested in discovering the health-promoting effects that pulse and whole grain proteins have to offer.

Rice Endosperm Protein Administration to Juvenile Mice Regulates Gut Microbiota and Suppresses the Development of High-Fat Diet-Induced Obesity and Related Disorders in Adulthood

Obesity and related disorders, which are increasing in adults worldwide, are closely linked to childhood diet and are associated with chronic inflammation. Rice endosperm protein (REP) intake during adulthood has been reported to improve lipid metabolism and suppress the progression of diabetic kidney disease in animal models. However, the effects of REP intake during childhood on adulthood health are unclear. Therefore, we used a mouse model to experimentally investigate the preconditioning effects of REP intake during childhood on the development of obesity and related disorders in adulthood. Male C57BL/6J mice were pair-fed a normal-fat diet containing casein or REP during the juvenile period and then a high-fat diet (HFD) containing casein or REP during adulthood. Mice fed REP during the juvenile period showed better body weight, blood pressure, serum lipid profiles, lipopolysaccharide (LPS)-binding protein levels, and glucose tolerance in adulthood than those fed casein during the juvenile period. HFD-induced renal tubulo-glomerular alterations and hepatic microvesicular steatosis were less evident in REP-fed mice than in casein-fed ones. REP intake during the juvenile period improved HFD-induced dysbiosis (i.e., Escherichia genus proliferation and reduced gut microbiota diversity), thereby suppressing endotoxin-related chronic inflammation. Indeed, REP-derived peptides showed antibacterial activity against Escherichia coli, a major producer of LPS. In conclusion, REP supplementation during the juvenile period may regulate the gut microbiota and thus suppress the development of obesity and related disorders in adulthood in mice.