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Background: In chronic kidney disease (CKD), the patients on a low-protein diet are considered to be at high risk of protein-energy wasting. Furthermore, a low-protein diet conceivably results in reduced intake of various nutrients. The purpose of this study was to evaluate the effects of a novel high-calorie, low-protein liquid formula containing eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), lactulose, raffinose, and indigestible dextrin on CKD patients. Methods: A randomized controlled trial was conducted on the Department of Nephrology at the Tokyo Medical University Hospital, Tokyo, Japan. Forty-three CKD patients prescribed a protein-restricted diet were randomly assigned to a supplement (SUP) or control (CTR) group. All patients received dietary counselling. Only the SUP group was given one or two packs (125 or 250 mL) daily of high-calorie, low-protein liquid formula. The intervention period was 16 weeks. Outcome measures of the study were body weight; body mass index (BMI); dietary protein, energy, and salt intake; estimated glomerular filtration rate (eGFR); serum levels of albumin, triglyceride and LDL-cholesterol; plasma fatty acid composition; plasma indoxyl sulfate level; creatinine clearance (Ccr); and urine protein excretion. Results: There were no differences in energy intake and protein intake between the two groups. Body weight, BMI, plasma eicosapentaenoic acid (EPA), and EPA/arachidonic acid (AA) ratio at 16 weeks were significantly higher in the SUP group than in the CTR group. At 16 weeks, the CTR group showed significant decline in eGFR and significant increase in plasma indoxyl sulfate, whereas the SUP group showed no significant changes from baseline. Conclusions: Supplementation of a novel liquid formula may be beneficial for the management in CKD patients on a protein-restricted diet.

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The indicator amino acid oxidation (IAAO) method is a novel method for determining protein requirements. Recently, the protein requirement of healthy young men was reevaluated using this method, and the currently recommended protein requirement based on nitrogen balance study was found to be deficient. Similarly, with respect to experimental animals, the protein concentration used widely in the experimental diets was assumed to be deficient. However, only a few studies have tested the IAAO method in experimental animals. In particular, there are no studies on the protein requirement of adult rats measured using this method. Therefore, we applied the IAAO method to adult rats, to determine their casein protein requirement. Male Wistar/ST rats (15-18 wk old, housed in lighting (lights on from 23:00 to 11:00) conditions) were provided with the test diet including graded casein (5, 7, 9,13,17, 21 and 25%) every 2 h from 11:00 to 17:00. Tracer administration of 13 C-phenylalanine was performed hourly from 14:00 to 17:00. Breath 13 CO2 was measured every 30 min after the first tracer administration. There were significant differences between the 13 CO2 concentration of the 5% and 17% casein groups at 17:00 and 18:00 (p,0.05). The mean casein protein requirement and recommended dietary allowance (RDA) were estimated to be 5.2 g/kg BW/d and 7.0 g/kg BW/d using the mixed-effect change point regression model, respectively. Our results indicated that the recommended casein value may be slightly deficient to satisfy the protein metabolic demand of some adult rats.

Slowly digestible carbohydrates are needed for nutritional support in diabetic patients with malnutrition. They are a good source of energy and have the advantage that their consumption produces a low postprandial peak in blood glucose levels because they are slowly and completely digested in the small intestine. A high-amount isomaltomegalosaccharide containing carbohydrate (H-IMS), made from starch by dextrin dextranase, is a mixture of glucose polymers which has a continuous linear structure of α-1,6-glucosidic bonds and a small number of α-1,4-glucosidic bonds at the reducing ends. It has a broad degree of polymerization (DP) distribution with glucans of DP 10 30 as the major component. In our previous study, H-IMS has been shown to exhibit slow digestibility in vitro and not to raise postprandial blood glucose to such levels as that raised by dextrin in vivo. This marks it out as a potentially useful slowly digestible carbohydrate, and this study aimed to evaluate its in vivo digestibility. The amount of breath hydrogen emitted following oral administration of H-IMS was measured to determine whether any indigestible fraction passed through to and was fermented in the large intestine. Total carbohydrate in the feces was also measured. H-IMS, like glucose and dextrin, did not result in breath hydrogen excretion. Carbohydrate excretion with dietary H-IMS was no different from that of glucose or water. These results show that the H-IMS is completely digested and absorbed in the small intestine, indicating its potential as a slowly digestible carbohydrate in the diet of diabetic patients.

The indicator amino acid oxidation method is a relatively new method for determining protein requirements. Our hypothesis was that the protein requirement of the casein-whey protein mixture (70% casein and 30% whey protein) was lower than the protein requirement of plain casein, because casein and whey proteins compensate for the lack of the first-limiting amino acids. The optimal mixing ratio was determined based on the amino acid scoring pattern which is used to calculate the digestible indispensable amino acid score. In this study, digestibility was not considered to determine the optimal mixing ratio because dairy protein is a good source of digestible protein. This study aimed to evaluate the protein requirements of Japanese young men by consuming casein and casein-whey protein mixture. Ten healthy young men (2260.2 y old) participated in 12 experiments according to a graded protein intake (0.5, 0.7, 0.9, 1.0, 1.2, 1.4 g/kg/d) of casein and casein-whey protein mixture. The mean protein requirement was calculated as the breakpoint of breath 13 CO2 enrichment using change-point regression models. The mean protein requirements of Japanese young men by consuming casein and casein-whey protein mixture were estimated to be 1.00 g/kg/d and 0.90 g/kg/d, respectively. These estimated requirements were consistent with the protein quality expected from the amount of the first-limiting amino acids. The indicator amino acid oxidation method may be useful to evaluate protein quality.