Can nutrition interventions tackle the global insulin affordability via improving diabetes management and reducing insulin demand?

Diabetes, a global health concern, requires insulin therapy. As insulin demand and prices rise dramatically, insulin affordability has increasingly become an issue facing patients with diabetes worldwide. To cut insulin costs, many patients ration their supply, which may have dire health consequences. This particularly affects lower-income populations, who are often forced to choose between purchasing their medications or paying for other necessities. Nutrition might be one solution for this. This commentary aims to provide comprehensive insight with historical context into intersectional components of diabetes in the global arena through analyses of insulin affordability, coupled with the critical role of nutrition intervention after searching the PubMed for relevant articles. More studies in personalized nutrition, supplementations, and dietary behaviors may develop evidence-based nutrition interventions to control diabetes. We argue that alongside price regulation, a greater focus to nutrition to address issues of food insecurity and food assistance programs may help to improve insulin affordability.

Reduction in the Dietary VA Status Prevents Type 2 Diabetes and Obesity in Zucker Diabetic Fatty Rats

We hypothesized that the vitamin A (VA) status regulates type 2 diabetes (T2D) development in Zucker diabetic fatty (ZDF) rats. Zucker Lean and ZDF rats at weaning were fed a VA deficient with basal fat (VAD-BF, no VA and 22.1% fat energy), VA marginal with BF (VAM-BF, 0.35 mg retinyl palmitate (RP)/kg), VA sufficient with BF (VAS-BF, 4.0 mg RP/kg), VAD with high fat (VAD-HF, 60% fat energy), VAM-HF or VAS-HF diet for 8 weeks, including an oral glucose tolerance test (OGTT) at week 7.5. The hepatic mRNA and proteins levels were determined using real-time PCR and Western blot, respectively. The VAD-BF/HF and VAM-BF/HF diets prevented peripheral hyperglycemia and attenuated obesity in ZDF rats, which occurred in the presence of the VAS-BF/HF diets. This lowered VA status reduced venous blood hyperglycemia, hyperinsulinemia and hyperlipidemia, and improved OGTT and homeostasis model assessment for insulin resistance results in ZDF rats. The expression levels of key hepatic genes for glucose and fat metabolism were regulated by VA status and dietary fat contents. An interaction between VA and HF condition was also observed. We conclude that the reduction in the dietary VA status in both BF and HF conditions prevents T2D and obesity in ZDF rats.

The Extraction of β-Carotene from Microalgae for Testing Their Health Benefits

β-carotene, a member of the carotenoid family, is a provitamin A, and can be converted into vitamin A (retinol), which plays essential roles in the regulation of physiological functions in animal bodies. Microalgae synthesize a variety of carotenoids including β-carotene and are a rich source of natural β-carotene. This has attracted the attention of researchers in academia and the biotech industry. Methods to enrich or purify β-carotene from microalgae have been investigated, and experiments to understand the biological functions of microalgae products containing β-carotene have been conducted. To better understand the use of microalgae to produce β-carotene and other carotenoids, we have searched PubMed in August 2021 for the recent studies that are focused on microalgae carotenoid content, the extraction methods to produce β-carotene from microalgae, and the bioactivities of β-carotene from microalgae. Articles published in peer-reviewed scientific journals were identified, screened, and summarized here. So far, various types and amounts of carotenoids have been identified and extracted in different types of microalgae. Diverse methods have been developed overtime to extract β-carotene efficiently and practically from microalgae for mass production. It appears that methods have been developed to simplify the steps and extract β-carotene directly and efficiently. Multiple studies have shown that extracts or whole organism of microalgae containing β-carotene have activities to promote lifespan in lab animals and reduce oxidative stress in culture cells, etc. Nevertheless, more studies are warranted to study the health benefits and functional mechanisms of β-carotene in these microalgae extracts, which may benefit human and animal health in the future.

The Interactions of Insulin and Vitamin A Signaling Systems for the Regulation of Hepatic Glucose and Lipid Metabolism

The pandemics of obesity and type 2 diabetes have become a concern of public health. Nutrition plays a key role in these concerns. Insulin as an anabolic hormonal was discovered exactly 100 years ago due to its activity in controlling blood glucose level. Vitamin A (VA), a lipophilic micronutrient, has been shown to regulate glucose and fat metabolism. VA's physiological roles are mainly mediated by its metabolite, retinoic acid (RA), which activates retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which are two transcription factors. The VA status and activations of RARs and RXRs by RA and synthetic agonists have shown to affect the glucose and lipid metabolism in animal models. Both insulin and RA signaling systems regulate the expression levels of genes involved in the regulation of hepatic glucose and lipid metabolism. Interactions of insulin and RA signaling systems have been observed. This review is aimed at summarizing the history of diabetes, insulin and VA signaling systems; the effects of VA status and activation of RARs and RXRs on metabolism and RAR and RXR phosphorylation; and possible interactions of insulin and RA in the regulation of hepatic genes for glucose and lipid metabolism. In addition, some future research perspectives for understanding of nutrient and hormone interactions are provided.

Vitamin A and Diabetes

Recently, research data have shown that vitamin A (VA, retinol) as a micronutrient participates in the regulation of glucose and lipid metabolism. Since diabetes is a metabolic disease, it is imperative to reveal the relationship of VA and diabetes. This review was aimed to summarize the current understanding of VA and its metabolites in diabetes. Since April of 2020, the authors have searched the PubMed using key words and retrieved articles that focused on diabetes and VA or its metabolites. Based on the published data, it appears that the development of type 1 diabetes leads to reduction of blood VA level in human and animals, and increase of hepatic VA store in experimental animals. On the other hand, the mutual impacts of type 2 diabetes and VA intake and blood VA level on each other appear to be uncertain. Retinoic acid, the active metabolite of VA, has been studied extensively for the treatment of diabetic complications. The current data appear to indicate that the development of diabetes is associated with changes of VA metabolism. More carefully designed clinical and laboratory experiments are needed to reveal the impacts of diabetes on VA metabolism and the role of VA in the development and treatment of diabetes.

The Potential Use of Vitamin C to Prevent Kidney Injury in Patients with COVID-19

The newly found SARS-CoV-2 has led to the pandemic of COVID-19, which has caused respiratory distress syndrome and even death worldwide. This has become a global public health crisis. Unfortunately, elders and subjects with comorbidities have high mortality rates. One main feature of COVID-19 is the cytokine storm, which can cause damage in cells and tissues including the kidneys. Here, we reviewed the current literature on renal impairments in patients with COVID-19 and analyzed the possible etiology and mechanisms. In addition, we investigated the potential use of vitamin C for the prevention of renal injury in those patients. It appears that vitamin C could be helpful to improve the outcomes of patients with COVID-19. Lastly, we discussed the possible protective effects of vitamin C on renal functions in COVID-19 patients with existing kidney conditions.

Roles of vitamin A in the regulation of fatty acid synthesis

Dietary macronutrients and micronutrients play important roles in human health. On the other hand, the excessive energy derived from food is stored in the form of triacylglycerol. A variety of dietary and hormonal factors affect this process through the regulation of the activities and expression levels of those key player enzymes involved in fatty acid biosynthesis such as acetyl-CoA carboxylase, fatty acid synthase, fatty acid elongases, and desaturases. As a micronutrient, vitamin A is essential for the health of humans. Recently, vitamin A has been shown to play a role in the regulation of glucose and lipid metabolism. This review summarizes recent research progresses about the roles of vitamin A in fatty acid synthesis. It focuses on the effects of vitamin A on the activities and expression levels of mRNA and proteins of key enzymes for fatty acid synthesis in vitro and in vivo. It appears that vitamin A status and its signaling pathway regulate the expression levels of enzymes involved in fatty acid synthesis. Future research directions are also discussed.

Long-term treatment with insulin and retinoic acid increased glucose utilization in L6 muscle cells via glycogenesis

The skeletal muscle regulates glucose homeostasis. Here, the effects of vitamin A metabolites including retinoic acid (RA) alone, and in combination with insulin, on glucose utilization were investigated in rat L6 muscle cells during the differentiation process. L6 cells were treated with differentiation medium containing retinol, retinal, RA, and (or) insulin. The glucose levels and pH values in the medium were measured every 2 days. The expression levels of insulin signaling and glycogen synthesis proteins, as well as glycogen content were determined. Retinal and RA reduced the glucose content and pH levels in the medium of the L6 cells. RA acted synergistically with insulin to reduce glucose and pH levels in the medium. The RA- and insulin-mediated reduction of glucose in the medium only occurred when glucose levels were at or above 15 mmol/L. Insulin-induced phosphorylation of Akt Thr308 was further enhanced by RA treatment through the activation of retinoic acid receptor. RA acted synergistically with insulin to phosphorylate glycogen synthase kinase 3β, and dephosphorylate glycogen synthase (GS), which was associated with increases in the protein and mRNA levels of GS. Increases in glycogen content were induced by insulin, and was further enhanced in the presence of RA. We conclude that activation of the RA signaling pathway enhanced insulin-induced glucose utilization in differentiating L6 cells through increases in glycogenesis.

Current understanding of glucose transporter 4 expression and functional mechanisms

Glucose is used aerobically and anaerobically to generate energy for cells. Glucose transporters (GLUTs) are transmembrane proteins that transport glucose across the cell membrane. Insulin promotes glucose utilization in part through promoting glucose entry into the skeletal and adipose tissues. This has been thought to be achieved through insulin-induced GLUT4 translocation from intracellular compartments to the cell membrane, which increases the overall rate of glucose flux into a cell. The insulin-induced GLUT4 translocation has been investigated extensively. Recently, significant progress has been made in our understanding of GLUT4 expression and translocation. Here, we summarized the methods and reagents used to determine the expression levels of Slc2a4 mRNA and GLUT4 protein, and GLUT4 translocation in the skeletal muscle, adipose tissues, heart and brain. Overall, a variety of methods such real-time polymerase chain reaction, immunohistochemistry, fluorescence microscopy, fusion proteins, stable cell line and transgenic animals have been used to answer particular questions related to GLUT4 system and insulin action. It seems that insulin-induced GLUT4 translocation can be observed in the heart and brain in addition to the skeletal muscle and adipocytes. Hormones other than insulin can induce GLUT4 translocation. Clearly, more studies of GLUT4 are warranted in the future to advance of our understanding of glucose homeostasis.

Encapsulation of vitamin D3 in gum arabic to enhance bioavailability and stability for beverage applications

Delivery of vitamin D₃ (VD₃ ) in foods should exhibit desirable physicochemical characteristics and improves absorption. In this study, gum arabic (GA) was investigated as a VD₃ carrier to encapsulate VD₃ . VD₃ dissolved in 5 mL ethanol corresponding to 0.3 to 6.0% mass of GA, was blended in 5.0% w/v GA solution, followed by freeze drying. The encapsulation efficiency decreased while loading capacity increased with an increased amount of VD₃ . At the highest VD₃ level, the loading capacity (3.47%) was the highest, and the encapsulation efficiency (61.24%) was satisfactory, and the treatment was further studied. The magnitude of negative zeta-potential increased from 3.1 to 31.0 mV at pH 2.0 to 7.4. During the 100-day storage at 3 °C of capsules reconstituted at pH 2.0 to 7.4, the hydrodynamic diameter decreased at all pH conditions, most evident for reduction to 81.3 nm at pH 7.4, and no precipitation was observed, indicating the significance of steric repulsion on capsule stability. Bioaccessibility of VD₃ in capsules (95.76%) was significantly higher than the nonencapsulated VD₃ (68.98%). The in vivo pharmacokinetic study in Sprague-Dawley rats after a single-dose of 300 µg VD₃ showed the area-under-curve of serum 25(OHD) level in 48 hr of the encapsulation treatment was 4.32-fold of the nonencapsulated VD₃ and more than twice higher than the VD₃ -GA physical mixture. During 2-week supplementation of 60 µg VD₃ /d, rats receiving capsules or physical mixture had 25(OH)D levels of at least 81 ng/mL higher than that of the nonencapsulated VD₃ group. The studied encapsulation system holds great potential as a value-added ingredient to supplement VD₃ in beverages with a wide pH range. PRACTICAL APPLICATION: The findings of this study demonstrated the improved dispersion stability and absorption of vitamin D₃ after encapsulation in gum arabic. The capsules exhibited good dispersion stability across a pH range between 2.0 and 7.4, showing potential application in beverages. Furthermore, the enhanced absorption of VD₃ after encapsulation highlights the nutritional benefits of the studied encapsulation system.

Altered staining patterns and expression level of Engrailed-2 in benign prostatic hyperplasia and prostate Cancer predict prostatic disease progression

BACKGROUND

Prostate cancer (PC), a common malignant tumor, is the second-leading cause of cancer death among American men. Its successful treatment greatly relies on the early diagnose. Engrailed-2 (EN2) has been confirmed being existed with a high level in the urine of PC patients. In this study, to explore the application of EN2 in PC, we detected the immunohistochemical staining difference and EN2 expression level between benign prostatic hyperplasia (BPH) and PC.

METHODS

We developed a monoclonal antibody against the helix 3 in EN2 and confirmed its specificity with Western blotting (WB) and immunofluorescence detecting the subcellular localization of endogenous and exogenous EN2 in three PC cell lines (LNCap, PC3, and DU145). We conducted immunohistochemical staining using this homemade antibody, and RT-PCR to detect the expression of EN2 in 25 PC and 25 BPH cases, and analyzed the correlation of EN2 expression and PC clinical staging.

RESULTS

The results of WB and immunofluorescence showed our homemade EN2 monoclonal antibody could specifically bind endogenous and exogenous EN2 protein in three different PC cell lines. Endogenous EN2 was generally expressed in the cytoplasm and exogenous EN2 mostly existed in the nucleus of these cell lines. Immunohistochemical staining in PC had extremely stronger signals than that in BPH, suggesting a higher EN2 expression level in PC, which was confirmed by RT-PCR. Interestingly, the stained areas in BPH tissues were mainly in nucleus and cytoplasm, while in PC tissues were mainly on cytomembrane. Moreover, the expression level of EN2 was positively correlated with the PC clinical staging.

CONCLUSION

Using our homemade EN2 antibody, we have found different staining patterns and expression level of EN2 in BPH and PC,which may be helpful to predict prostatic disease progression.

Clinical use of low-dose aspirin for elders and sensitive subjects

The use of low-dose aspirin (LDA) has been a common preventive measure to reduce the risk of cardiovascular events. This is attributed to aspirin’s ability to inhibit platelet activation. On the other hand, the use of LDA in human subjects has been associated with the development of gastrointestinal injuries like ulcer and bleeding, especially for those sensitive subjects such as elder human subjects. This opinion review will summarize the recent clinical reports regarding the use of LDA and the development of gastrointestinal conditions in China. Based on these reports, it seems that the use of LDA is commonly associated with gastrointestinal injuries, and stopping its use leads to recovery in elderly subjects. Therefore, we would like to suggest that gastroduodenal health and conditions should be seriously taken into consideration when LDA is recommended to the elderly, or other alternative means to reduce the risk of cardiovascular events such as nutritional interventions should be suggested.

Vitamin A status affects weight gain and hepatic glucose metabolism in rats fed a high-fat diet

Whether vitamin A (VA) has a role in the development of metabolic abnormalities associated with intake of a high-fat diet (HFD) is unclear. Sprague-Dawley rats after weaning were fed an isocaloric VA sufficient HFD (VAS-HFD) or a VA deficient HFD (VAD-HFD) for 8 weeks. Body mass, food intake, liver and adipose tissue mass, and the hepatic expression levels of key proteins for metabolism were determined. VAD-HFD rats had lower body, liver, and epididymal fat mass than VAS-HFD rats. VAD-HFD rats had lower hepatic protein expression levels of cytochrome P450 26A1, glucokinase, and phosphoenolpyruvate carboxykinase than VAS-HFD rats. VAD-HFD rats had higher protein levels of glycogen synthase kinase (GSK)-3α and lower levels of GSK-3β, but not glycogen synthase, than VAS-HFD rats. VAD-HFD rats had higher hepatic levels of insulin receptor substrate-1 (IRS-1), insulin receptor β-subunit, mitogen-activated protein kinase proteins, and peroxisome proliferator-activated receptor-gamma coactivator 1α mRNA, and lower level of IRS-2 protein than VAS-HFD rats. These results indicate that in a HFD setting, VA deficiency attenuated HFD-induced obesity, and VA status altered the expression levels of proteins required for glucose metabolism and insulin signaling. We conclude that VA status contributes to the regulation of hepatic glucose and lipid metabolism in a HFD setting, and may regulate hepatic carbohydrate metabolism.

Fish oil alleviates circadian bile composition dysregulation in male mice with NAFLD

Our previous studies have found that fish oil rich in ω-3 polyunsaturated fatty acids (ω-3 PUFA) protects against non-alcoholic fatty liver disease (NAFLD) in mice. This study was aimed to explore the effects of fish oil on high fat diet (HFD)-induced circadian bile composition chaos. Male C57BL/6 mice were randomly divided into three groups, a control group (CON), a HFD group and a fish oil (FO) group, which were fed a normal chow diet, a HFD, and a HFD supplemented with FO, respectively for 12 weeks. At the end of the experiment, liver tissue, blood and bile samples were processed at 12-h intervals with the first one at zeitgeber time 0 (ZT0) and the second at zeitgeber time 12 (ZT12). Metabolites in bile were determined using UPLC-QTOF-MS, screened using multivariate statistical analysis, and analyzed using KEGG database and Metaboanalyst. The expression levels of key proteins in bile acid metabolism were examined using western blot. Results of biochemical analysis and H&E staining illustrated that feeding of HFD induced NAFLD, which was ameliorated in FO group. The bile content of each group at ZT0 (CON, HFD, or FO group) was respectively higher than that at ZT12 (P<.05). The metabolic pathway analysis of differential metabolites showed that these differences were correlated with amino acid metabolism, fatty acid biosynthesis and primary bile acid synthesis at ZT0. FO supplement could modify bile composition, which was related to the influence of its ω-3 PUFA on liver metabolism. ω-3 PUFA may also regulate the circadian rhythm of bile metabolism.

Long sleep duration predicts a higher risk of obesity in adults: a meta-analysis of prospective cohort studies

BACKGROUND

The connections between long sleep duration and obesity or weight gain warrant further examination. This meta-analysis aimed to evaluate whether long sleep duration was associated with the risk of obesity, weight gain, body mass index (BMI) change or weight change in adults.

METHODS

PubMed, Embase, Cochrane Library, Elsevier Science Direct, Science Online, MEDLINE and CINAHL were searched for English articles published before May 2017. A total of 16 cohort studies (n = 329 888 participants) from 8 countries were included in the analysis. Pooled relative risks (RR) or regression coefficients (β) with 95% confidence intervals (CI) were estimated. Heterogeneity and publication bias were tested, and sensitivity analysis was also performed.

RESULTS

We found that long sleep duration was associated with higher risk of obesity (RR [95% CI] = 1.04 [1.00-1.09], P = 0.037), but had no significant associations with weight gain, BMI change or weight change. Long sleep duration increased the risk of weight gain in three situations: among men, in studies with <5 years follow-up, and when sleep duration was 9 or more hours.

CONCLUSIONS

Long sleep duration was associated with risk of obesity in adults. More cohort studies with objective measures are needed to confirm this relationship.

Diagnostic Value and Safety of Emergency Single-Balloon Enteroscopy for Obscure Gastrointestinal Bleeding

BACKGROUND

This study assesses the diagnostic performance of emergency single-balloon enteroscopy (SBE) for obscure gastrointestinal bleeding (OGIB) under general anesthesia versus conscious sedation.

STUDY

The data of 102 OGIB in-patients from June 2015 to June 2018 were retrospectively analyzed. The diagnosis and detection rates and adverse events were calculated overall and in relation to age, gender, type of operation and anesthesia, bleeding type, different times of examination, and SBE route. All statistical analyses were performed using SPSS 24.0, and the diagnosis and detection rates were compared using the Chi-square test.

RESULTS

Among the 102 patients, 66 patients had positive findings, while 11 patients had suspected positive findings, and the diagnosis and detection rates were 64.7% and 75.5%, respectively. Ulcers (19.6%) and tumors (16.7%) were the most common causes of OGIB. There were no statistical differences in diagnosis and detection rates between the ages of ≥60 and <60 and between different genders. Patients with emergency SBE had higher diagnosis and detection rates (68.6% vs. 35.3%, P = 0.023; 80.0% vs. 47.1%, P = 0.016, respectively), when compared with nonemergency SBE patients. The diagnosis rate at 24 hours was higher than that at 2-7 days and one week (88.0% vs. 61.5%, P = 0.030; 88.0% vs. 53.8%, P = 0.007). For overt bleeding, the difference in diagnosis rates at 24 hours, 2-7 days, and one week was statistically significant (100.0% vs. 57.1%, P = 0.006; 100.0% vs. 57.1%, P = 0.006). For occult bleeding, the pairwise comparison revealed no statistical difference. Patients with general anesthesia had a higher detection rate, when compared to patients with conscious sedation (87.9% vs. 63.9%, P = 0.004). In addition, adverse events under general anesthesia were lower, when compared to adverse events under conscious sedation (28.8% vs. 69.4%, P = 0.020). There was no significant difference in adverse events at the different time points (P > 0.05).

CONCLUSION

Emergency SBE under general anesthesia achieves higher diagnosis and detection rates, and fewer adverse events under conscious sedation, when compared to nonemergency SBE, regardless of the route. For patients with overt bleeding, it is easier to find lesions by emergency SBE within 24 hours.