Yasuaki Wada

Dairy products formulated with bioactives are widely distributed in Japan, but it remains to be clear whether a regular consumption of these products would help reduce the risks of incidental functional disability and dementia in older adults. This study aimed to investigate Japanese subjects aged ≥65 y (n=629) that routinely consumed three functional dairy products, a calcium-enriched milk supplemented with Bifidobacterium longum BB536, a yogurt supplemented with lactoferrin, B. longum BB536 and heat-killed Lacticaseibacillus paracasei MCC1849, and a drinkable yogurt supplemented with lactoferrin, B. longum BB536 and heat-killed L. paracasei MCC1849, through a home delivery service. Intake frequency and intake duration of these functional dairy products were compared with the risk scores of incident functional disability and dementia, developed by the Japan Gerontological Evaluation Study. In the participants aged <75 y, the incident functional disability risk was significantly maintained or decreased in the participants with the long intake duration level compared with the short intake duration level (OR, 95% CI: 0.48, 0.25–0.93). In the participants aged ≥75 y, the dementia risk was significantly maintained or decreased in the participants with the high intake frequency level compared with the low intake frequency level (OR, 95% CI: 0.46, 0.22–0.95). A high intake frequency or long term duration of these functional dairy products may be effective in preventing an aging-related increase in the risks of incident functional disability and dementia in older adults, but this warrants further investigation using different products containing different bioactives.

Many improvements have been made to bring infant formula (IF) closer to human milk (HM) regarding its nutritional and biological properties. Nevertheless, the protein components of HM and IF are still different, which may affect their digestibility. This study aimed to evaluate and compare the protein digestibility of HM and IF using the infant INFOGEST digestion method. Pooled HM and a commercial IF were subjected to the infant INFOGEST method, which simulates the physiological digestion conditions of infants, with multiple directions, i.e. the curd state, gel images of SDS-PAGE, molecular weight distribution, free amino acid concentrations and in vitro protein digestion rate. HM underwent proteolysis before digestion and tended to have a higher protein digestion rate with finer curds during gastric digestion, than the IF. However, multifaceted analyses showed that the protein digestibility of HM and IF was not significantly different after gastrointestinal digestion. In conclusion, the infant INFOGEST method showed that the digestibility of HM and IF proteins differed to some extent before digestion and after gastric digestion, but not at the end of gastrointestinal digestion. The findings of this study will contribute to the refinement of IF with better protein digestibility in infant stomach.

Human serum albumin is categorized into human mercaptalbumin (HMA) and human non-mercaptalbumin (HNA), according to the redox state of the cysteine residue at position 34. The ratio of HMA to total albumin (%HMA) is a novel biomarker of oxidative stress as well as protein nutritional status, but measuring %HMA normally requires an expensive analyzer such as HPLC and LC-MS, and can hardly be conducted in many clinical sites. To address this issue, we aimed to develop a methodological basis for estimating %HMA without these analyzers. An analytical method was investigated consisting of three steps, i.e., 1) removal of HMA from serum or plasma by using a thiol-binding resin (i.e., thereby obtaining a HNA fraction), 2) determination of both total albumin and HNA concentrations by a colorimetric assay or ELISA, and 3) calculation of %HMA. Proof-of-concept experiments, using serum and plasma samples of 4 adult volunteers, showed that the estimated value of %HMA obtained by this analytical method was significantly correlated with the theoretical value of %HMA determined by HPLC. The subsequent validation experiment, using 86 serum samples of pregnant women in the Japanese participants of SMILE Iwamizawa, also confirmed the significant association between the estimated and theoretical values of %HMA. This analytical method can be a basis to determine %HMA without using HPLC or LC-MS, contributing to the universalization of %HMA measurement as a clinical test.

Maternal diet may affect human milk macronutrients, but it remains to be elucidated whether this is also influential in infant growth. This study aimed to examine (1) how maternal diet influences human milk macronutrients, and (2) to what extent the variation in milk macronutrients affects infant growth during the first month of life. In 71 Japanese lactating women, maternal dietary information was collected from the brief-type self-administered diet history questionnaire, and anthropometry of mother–infant dyads was collected from medical records. Macronutrients in milk were analyzed by a Human Milk Analyzer. Maternal retinol intake was associated with the carbohydrate content in human milk at 1-month postpartum (standardized β coefficient: 0.287; p = 0.038). Moreover, the energy content in human milk was associated with an increase in the weight standard deviation score based on the WHO growth standard at 1 month of age (standardized β coefficient: 0.399; p = 0.046). Nevertheless, the milk macronutrient was not associated with the risk of infant growth abnormalities. In conclusion, a part of the maternal diet impacts macronutrient contents in human milk, but milk macronutrients have a limited effect on infant growth only within the normal growth curve during the first month of life.

The INFOGEST method is a valuable tool for understanding and monitoring food digestion as an alternative to in vivo assays. However, few studies have compared animal and alternative protein sources in terms of protein quality using the INFOGEST method. This study aimed to evaluate the protein quality of milk-, plant-, and insect-based protein materials by in vitro protein digestibility and in vitro digestible indispensable amino acid score (DIAAS), following the INFOGEST method. Milk-based protein materials had the highest protein digestibility (86.1-90.8%), followed by soy (85.1%) and wheat (82.3%). These materials had significantly higher protein digestibility compared with zein (65.1%), cricket (63.6%), and mealworm (69.5%). Additionally, the mean values of in vitro DIAAS of milk-based protein materials (105.0-137.5) were higher than those of plant- and insect-based protein materials (1.9-91.0). Milk-based protein materials have higher protein quality than plant- and insect-based protein materials by the nutritional evaluation following the INFOGEST digestion method.