The role of vitamin A in the pathophysiological context of coronavirus disease 2019 (COVID-19) represents a current challenge, given the major impact of COVID-19 on morbidity and mortality and the importance of retinol in pulmonary and immunomodulatory functions. The aim of this review is to assess the relationship between vitamin A nutritional status and clinical outcomes in people with COVID-19. The PubMed, Web of Science, Scopus and ScienceDirect databases were used to search for observational studies that assessed retinol levels in hospitalized individuals with COVID-19, following the PRISMA recommendations. A total of 1,912 articles were identified and seven met the inclusion criteria. Four studies showed borderline or deficient retinol blood levels (retinol <0.20 mg/L or <0.70 mol/L) in people with COVID-19, associated with worsened clinical outcomes. In the other three studies lower mean values of this vitamin were identified in COVID-19 symptomatic groups compared to asymptomatic or convalescent groups that showed worse clinical outcomes. The results suggest a possible association between retinol and COVID-19 outcomes. However, there is a clear need to develop clinical trials to elucidate the role of vitamin A in the pathophysiological process of COVID-19.

Previous studies on the relationship between dietary carotenoids and obesity are few, and the results are inconsistent. Therefore, the purpose of this study was to evaluate the associations between total carotenoids, α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein+zeaxanthin intakes and the risk of obesity in adults. This cross-sectional study was carried out based on the National Health and Nutrition Examination Survey (NHANES) 2007–2018. The two 24-h dietary recall interviews were used to collect dietary carotenoids data. Obesity was defined as body mass index (BMI) ≥30 kg/m². Logistic regression models and restricted cubic spline were used to assess the relationships between carotenoids intakes and obesity. A total of 25,868 adults aged 20 and over were enrolled in the present study. In multivariate logistic regression model 2, the odds ratios (ORs) with 95% confidence intervals (CIs) of obesity were 0.82 (0.74–0.91), 0.80 (0.72–0.90), 0.77 (0.69–0.87), 0.85 (0.76–0.95), and 0.80 (0.73–0.89) for the highest versus the lowest of total carotenoids, α-carotene, β-carotene, β-cryptoxanthin, and lutein+zeaxanthin intakes, respectively. Dose-response analyses suggested that the carotenoids mentioned above were inversely related to obesity in a nonlinear manner. In multivariate-adjusted model 2, total carotenoids intake were associated with lower risk of Class 1, 2, and 3 obesity. This study indicated that intakes of total carotenoids, α-carotene, β-carotene, β-cryptoxanthin, and lutein+zeaxanthin were inversely associated with the risk of obesity.

Retinol-binding protein 4 (RBP4) is a retinol transporter in the blood plasma. Many diseases alter the plasma or serum levels of RBP4. Since serum RBP4 concentrations have been reported to decrease in hyperthyroidism, this study investigated whether serum RBP4 concentrations increased or remained constant in hypothyroidism. In sera from patients with hypothyroidism (n=71), hyperthyroidism (n=30), and healthy subjects (n=20), serum concentrations of RBP4 (sum of holo- and apo-RBP4), retinol, albumin, creatinine, and related constituents were measured, and RBP4/retinol molar ratio (as an index of apo-RBP4) and estimated glomerular filtration rate (eGFR) were calculated. The results showed that serum RBP4 concentrations tended to increase with decreasing free thyroxine concentrations, but there were no significant differences among patients with hypothyroidism, hyperthyroidism, and healthy subjects. When patients with hypothyroidism were subdivided by serum RBP4 level using 2.1 μmol/L cut-off value, patients with >2.1 μmol/L were revealed to be patients with older age having lower tri-iodothyronine, higher holo-RBP4, higher apo-RBP4, higher retinol, higher RBP4/retinol molar ratio, and lower eGFR than those in patients with <2.1 μmol/L. Multiple regression analysis showed significant associations between serum RBP4 levels and explanatory variables (retinol and eGFR). Although serum levels of RBP4 prior to the onset of renal dysfunction may affect the present concentrations, we conclude that the increase of serum RBP4 (both holo- and apo-RBP4) in patients with hypothyroidism was attributed to the decline in eGFR. In contrast, serum RBP4 concentration remained constant without renal dysfunction.

Senescence marker protein-30 (SMP30) is a senescence marker molecule that exhibits lactonase activity in the ascorbic acid (AsA) biosynthesis pathway, except in primate mammals, including humans. Although numerous studies have shown that hepatic AsA deficiency causes acute-phase responses, details of the relationship between SMP30 expression and acute-phase responses in AsA-deficient conditions remain to be elucidated. Here, we investigated the effects of AsA deficiency on the relationship between SMP30 and acute liver injury in osteogenic disorder Shionogi (ODS) rats, which have a hereditary defect in AsA biosynthesis. Male-ODS rats (4 wk old) were pair-fed an AsA-free diet with distilled or 0.1% AsA-dissolved water for 14 d. Under AsA-deficient conditions, hepatic SMP30 protein level was decreased and liver injury markers, the serum aspartate aminotransferase/alanine transaminase ratio and cytokine-induced neutrophil chemoattractant-1 (CINC-1) concentration, were elevated. In contrast, SMP30 protein level in extracellular vesicles (EVs) was significantly increased in addition to the positive acute proteins haptoglobin and asialoglycoprotein receptor 1 (ASGPR1), hepatic-derived specific markers expression under AsA-deficient conditions. AsA deficiency also activated signal transducer and activator of transcription 3 (STAT3) which is linked to EVs release in the liver. These results suggest that the release of SMP30 in EVs by AsA deficiency is involved with acute-phase responses.

Serum 25-hydroxyvitamin D₃ [25(OH)D₃] concentrations have been associated with diabetic retinopathy (DR) severity. Blood cadmium has also been reported to be associated with the presence of DR. Besides, cadmium can decrease the formation of calcitriol (active vitamin D) in blood. However, the effect of blood cadmium on the association between 25(OH)D₃ and DR severity has not been studied comprehensively. Therefore, we designed this cross-sectional study to assess the effect modification of blood cadmium on the association between 25(OH)D₃ and DR severity in the U.S. population with type 2 diabetes (T2D). This study was conducted using NHANES from 2005 to 2008. By having stratified participants based on blood cadmium category (low blood cadmium<2.76 nmol/L; high blood cadmium≥2.76 nmol/L), we evaluated the difference (interaction test) between the relationship of 25(OH)D₃ with the severity of DR among low blood cadmium and high blood cadmium participants using multivariable logistic regression. In this cross-sectional study, a total of 283 participants were included. In the high blood cadmium group, the odds ratio for severe non-proliferative retinopathy (NPDR)/proliferative retinopathy (PDR) of high 25(OH)D₃ (≥50 nmol/L) group was 0.26 (95% CIs: 0.09–0.69, p=0.01) compared with the reference group (low 25(OH)D₃ group). Furthermore, there was evidence of interaction between 25(OH)D₃ and blood cadmium on decreasing the incidence of severe NPDR/PDR. Our study indicated that blood cadmium might affect the association of 25(OH)D₃ with DR severity in participants with T2D. More randomized controlled trials are needed to provide more evidence of such a finding.

The Vitamin D Deficiency Questionnaire for Japanese (VDDQ-J) has been developed as an alternative indicator of the vitamin D nutritional status when serum 25(OH)D measurement is unavailable. In the present study, we compared the usefulness of the VDDQ-J with that of serum 25(OH)D concentration and examined the relationship among vitamin D, DXA-based body composition, and muscle strength in 163 anti-aging health check examinees. The median age, 25(OH)D concentration and VDDQ-J score were 62.0 y, 20.1 ng/mL and 22.0 points, respectively. In total, 47.9% of the subjects had serum 25(OH)D concentrations of <20 ng/mL. The VDDQ-J score was significantly negatively correlated with the serum 25(OH)D concentration, and the positive predictive value for vitamin D deficiency was 86.3%. The prevalence of sarcopenia was 6.1%. Low 25(OH)D levels and high VDDQ-J scores were significantly associated with low muscle mass in both univariate analysis and multiple linear regression analysis. The serum 25(OH)D level showed a significant negative correlation with body fat mass. The VDDQ-J score was selected as a significant determinant of low skeletal muscle mass index (<7.0 kg/m² for men and <5.4 kg/m² for women) by a multiple logistic regression analysis. In conclusion, the present study showed that a low vitamin D nutritional status as indicated by both low 25(OH)D levels, and high VDDQ-J scores was associated with low muscle mass and the VDDQ-J is considered useful not only for the detection of vitamin D deficiency but also in the screening of individuals with low muscle mass and a high risk of sarcopenia.

Zinc (Zn) deficiency is one of the most common nutritional deficiencies worldwide. It is associated with reduced nutritional status and has been reported in cases of growth retardation, alopecia, and decreased serum alkaline phosphatase (ALP). It has also been reported to occur during total parenteral nutrition (TPN) administration and is associated with various diseases, such as liver diseases, diabetes, and kidney disease. We used Zn-deficient mice of ICR and C57BL/6J strains to investigate the various effects of Zn deficiency on the body, assuming that a healthy person may also become deficient in Zn either due to an unbalanced diet or malabsorption. The results showed that a Zn-deficient diet suppressed body weight gain and increased the tissue weight of the kidneys and cecum in both strains of mice. Biochemical data showed no decrease in serum ALP activity in either strain. Furthermore, in C57BL/6J mice, a Zn-deficient diet caused alopecia, loss of villi in the small intestine, and eventually affected the intestinal mucosa, which could be a risk factor for poor nutritional status. Although previous reports have shown that serum ALP activity is decreased during Zn deficiency, this is the first study that used 4-wk-old mice of ICR and C57BL/6J strains to show that serum ALP activity, which is a Zn deficiency marker, did not decrease in the two strains of Zn-deficient mice; furthermore, a Zn-deficient diet causes various symptoms.

Few reports have described sarcopenic obesity in patients with stroke. This study aimed to investigate the prevalence of sarcopenic obesity, as defined by the European Society for Clinical Nutrition and Metabolism (ESPEN) and European Association for the Study of Obesity (EASO) consensus statement, in patients with acute stroke and to determine whether it was associated with improved physical function at discharge. This retrospective cohort study was conducted from May 2020 to November 2021 in patients with acute stroke. Sarcopenic obesity was determined using the ESPEN and EASO consensus statement. The main outcome was physical function based on the Functional Independence Measure motor score at discharge. Multiple regression analysis was conducted to evaluate the association between sarcopenic obesity and the Functional Independence Measure motor score. This study included 276 patients (182 men; mean age, 72.4 y). Sarcopenic obesity screened for obesity with body mass index >27.5 was found in 11 (4%) patients. Multiple regression analysis revealed that sarcopenic obesity screened for obesity with body mass index >27.5 was not significantly associated with the Functional Independence Measure motor score at discharge (β=0.038; 95% confidence interval: −0.046, 0.123; p=0.369). This study revealed a prevalence rate of 4% for sarcopenic obesity diagnosed by the ESPEN and EASO criteria and showed that sarcopenic obesity was not statistically associated with activities of daily living at acute discharge in patients with stroke.

Metabolic syndrome (MetS) poses increased risks for non-communicable diseases, increasing all-cause mortality, disability, and healthcare costs. Beta-carotene as the major carotenoid is identified to play an important role in the pathophysiology of MetS. The present study aimed to investigate the association between serum beta-carotene levels with metabolic syndrome and metabolic risk factors among a cohort of teachers in Peninsular Malaysia. This cross-sectional study investigated a sub-sample of 645 serum samples which were randomly selected for beta-carotene determination. Socio-demographic, lifestyle and metabolic risk factors were measured following standard protocols. There were equal proportions of males and females, with majority Malays (69%) followed by the Chinese (24%) and Indians (6.5%). The prevalence of MetS was 24.8% with abnormal waist circumference and high blood pressure as the most commonly reported metabolic risk factors. The median serum beta-carotene was 5.15 (5.07) μmol/L. Serum beta-carotene in the lowest quartile (Q1) was found to be significantly associated with MetS (OR: 5.81; 95% CI: 2.96, 11.38) and metabolic risk factors, namely triglycerides (OR: 6.38; 95% CI: 3.04, 13.35), fasting blood sugar (OR: 3.32; 95% CI: 1.48, 7.43), HDL-cholesterol (OR: 2.88; 95% CI: 1.58, 5.26) and waist circumference (OR: 2.94; 95% CI: 1.73, 5.01), after adjusted for potential confounders. In summary, participants with lower serum beta-carotene had higher odds for MetS and the above-mentioned metabolic risk factors.

This study examined the relationship between parents’ self-efficacy for preparing meals combining the five food groups (grains, fish and meat, vegetables, milk, and fruits) and the dietary intake of their children who were elementary and junior high school students belonging to a sports club. A total of 365 children completed a self-reported dietary intake form, and their parents completed a questionnaire on self-efficacy for preparing meals combining the five food groups. Logistic regression analysis was conducted to assess the relationship between the children’s intake of the combined five food groups and parents’ self-efficacy score, with frequency of meals combining the five food groups as the dependent variable and the self-efficacy score as the independent variable. In a multivariate logistic regression analysis that was higher self-efficacy scores were associated with a higher frequency of meals that contained all five food groups, with an odds ratio of 1.06 (95% confidence interval: 1.00–1.12; p=0.036). Significant positive correlations were also found between parents’ self-efficacy and the number of times children consumed four food types (fish and meat, vegetables, milk, and fruits) at breakfast and three food types (grains, milk, and fruits) at dinner. These findings suggest that parents’ self-efficacy for preparing meals combining the five food groups was associated with the number of meals with all five food groups consumed by their children, who were fifth and sixth graders in elementary and junior high school and belonged to sports clubs.

Previous studies conducted have reported higher mortality and heart failure readmission rates in heart failure patients with selenium deficiency. However, these studies included patients with advanced heart failure, which may have confounded the relationship between selenium deficiency and heart failure pathology. This study aimed to explore the clinical characteristics and outcomes of heart failure patients with selenium deficiency who were newly diagnosed and hospitalized for heart failure in Japan. A total of 256 patients, who were admitted to our hospital for the first time due to heart failure, were included in this study. The patients were divided into two groups: a low selenium group (LS group, n=132) and a normal selenium group (NS group, n=124). Clinical features and outcomes were compared between the two groups, including 1-y mortality and readmissions due to heart failure. Among the patients admitted with heart failure, 51.6% exhibited selenium deficiency. The LS group showed a higher proportion of females (65.4% vs. 46.4%, p=0.003) and lower albumin levels (3.2±0.5 g/dL vs. 3.5±0.5 g/dL, p<0.001) compared to the NS group. The LS group had a significantly higher readmission rate for heart failure (31.8% vs. 17.7%, p=0.009). Multivariate analysis revealed heart failure patients with low selenium as an independent factor for readmission due to heart failure. Newly diagnosed heart failure patients with low selenium demonstrated a high readmission rate for heart failure.

In this study, Continuous Glucose Monitoring, a 24-h continuous sensor measurement of the glucose level, was performed on 35 female university students in their 20s. The results showed that 51.4% of the subjects had at least one episode of low sensor glucose level <54 mg/dL during the entire measurement period. This severe low glucose level condition was defined as lower sensor glucose values and it tended to occur more frequently during the early morning hours, especially from 3:00 am to 7:00 am. There were no significant differences in the BMI, the average number of steps, the total energy intake, the energy ratio of proteins, fats, or carbohydrates, or the alcohol intake between the lower sensor glucose values occurrence and the non-lower sensor glucose values occurrence groups. In regard to the early morning lower sensor glucose values observed in healthy female university students, we consider that further studies are required.

Branched-chain α-ketoacid dehydrogenase (BCKDH) complex is a rate-limiting enzyme in branched-chain amino acid catabolism and is subject to inactivation via phosphorylation by BCKDH kinase (BDK). In the present study, we examined the effects of vitamin D-deficiency on hepatic BCKDH and BDK activities in rats. Rats fed a vitamin D-deficient diet long-term showed a slight but significant decrease in plasma Ca concentration, which was associated with an elevation of BCKDH activity and a decrease in BDK activity. These results suggest that vitamin D deficiency promotes BCAA catabolism via BCKDH activation, which resulted from BDK suppression. It is proposed that Ca²⁺-dependent BDK inhibition by thiamine pyrophosphate may be involved in the BDK suppression.