Associations Between 25-Hydroxyvitamin D, Kidney Function, and Insulin Resistance Among Adults in the United States of America

Polyphenols: a route from bioavailability to bioactivity addressing potential health benefits to tackle human chronic diseases

Chronic pathologies or non-communicable diseases (NCDs) include cardiovascular diseases, metabolic syndrome, neurological diseases, respiratory disorders and cancer. They are the leading global cause of human mortality and morbidity. Given their chronic nature, NCDs represent a growing social and economic burden, hence urging the need for ameliorating the existing preventive strategies, and for finding novel tackling therapies. NCDs are highly correlated with unhealthy lifestyle habits (such as high-fat and high-glucose diet, or sedentary life). In general, lifestyle approaches that might improve these habits, including dietary consumption of fresh vegetables, fruits and fibers, may contrast NCD symptoms and prolong life expectancy of affected people. Polyphenols (PPLs) are plant-derived molecules with demonstrated biological activities in humans, which include: radical scavenging and anti-oxidant activities, capability to modulate inflammation, as well as human enzymes, and even to bind nuclear receptors. For these reasons, PPLs are currently tested, both preclinically and clinically, as dietary adjuvants for the prevention and treatment of NCDs. In this review, we describe the human metabolism and bioactivity of PPLs. Also, we report what is currently known about PPLs interaction with gastro-intestinal enzymes and gut microbiota, which allows their biotransformation in many different metabolites with several biological functions. The systemic bioactivity of PPLs and the newly available PPL-delivery nanosystems are also described in detail. Finally, the up-to-date clinical studies assessing both safety and efficacy of dietary PPLs in individuals with different NCDs are hereby reported. Overall, the clinical results support the notion that PPLs from fruits, vegetables, but also from leaves or seeds extracts, are safe and show significant positive results in ameliorating symptoms and improving the whole quality of life of people with NCDs.

Association between vitamin D serum levels and insulin resistance assessed by HOMA-IR among non-diabetic adults in the United States: Results from NHANES 2007-2014

Insulin resistance, a pathological response to insulin hormone in insulin-dependent cells, is characterized by the presence of high glucose and insulin concentrations. The homeostasis model of insulin resistance (HOMA-IR) is one of the most used indexes to estimate insulin resistance by assessing the fasting glucose and insulin levels. An association was observed between vitamin D levels and insulin resistance, which varied in different ethnic groups, and there is some evidence that vitamin D supplementation could contribute to the improvement of insulin resistance. This study assessed the association between 25-hydroxyvitamin D (25[OH]D) concentration and HOMA-IR in American adults aged 20 years and older, without diabetes and other chronic diseases that can influence insulin resistance. The data from the National Health and Nutrition Examination Survey (NHANES) 2007–2014 were used by exploiting the free and publicly-accessible web datasets. Linear regression models were performed to evaluate the association between serum 25(OH)D concentration and HOMA-IR, and a negative association was observed, which remained significant following the adjustment for age, gender, race/ethnicity, education, body mass index (BMI), physical activity, the season of examination, current smoking, hypertension, the use of drugs which can influence insulin resistance, serum bicarbonates, triglycerides, and calcium and phosphorus levels. Only in non-Hispanic Blacks was this inverse association between vitamin D and HOMA-IR not observed in the fully adjusted model. Further studies are needed to explain the mechanisms of the observed ethnic/racial differences in the association of vitamin D levels with HOMA-IR.

Association between vitamin D and insulin resistance in adults with latent tuberculosis infection: Results from the National Health and Nutrition Examination Survey (NHANES) 2011-2012

BACKGROUND

Evidence demonstrated that vitamin D insufficiency was involved in insulin resistance (IR) pathogenesis and associated with tuberculosis. However, the association of vitamin D and IR in patients with latent tuberculosis infection (LTBI) remains unclear. This study aims to evaluate the association between vitamin D and insulin resistance in US adults with LTBI.

METHOD

National Health and Nutrition Examination Survey (NHANES) participants ≥ 20 years during the years 2011-2012 with positive QuantiFERON®-TB Gold-In-Tube (QFT) or tuberculin skin testing (TST) were enrolled in present study. Participants with LTBI were divided into 2 groups: (1) vitamin D insufficiency group (n = 267), and (2) vitamin D sufficiency group (n = 437).

RESULTS

Weighted analysis of all the population in the study showed that serum 25(OH)D inversely correlated with HOMA-IR (r = -0.14, P = 0.008). The vitamin D insufficiency group had higher fasting insulin (17.5 (1.38) vs. 15.29 (3.1), respectively, P = 0.0013) and HOMA-IR (5.0 (0.4) vs. 4.5 (1), respectively, P = 0.013) than the vitamin D sufficiency group. In adjusted analysis, vitamin D levels was independently associated with insulin resistance (adjusted OR [aOR] 2.74; 95% CI, 1.01-7.48, p = 0.0489).

CONCLUSIONS

Taken together, our study suggested that serum 25(OH) D concentrations were inversely and independently associated with HOMA-IR in LTBI.

The kidney reabsorption-related Magnesium Depletion Score is associated with increased likelihood of abdominal aortic calcification among US adults

BACKGROUND

Kidney reabsorption has a vital role in magnesium homeostasis. This study aimed to determine the relationship between the kidney reabsorption-related magnesium depletion score (MDS) and abdominal aortic calcification (AAC).

METHODS

We obtained the data of 2640 individuals from the National Health and Nutrition Examination Survey (NHANES) database and analyzed the relationship between MDS and AAC scores. MDS is a scoring system developed to predict status of magnesium deficiency that fully considered the pathophysiological factors influencing the kidneys' reabsorption capability. AAC was quantified by the Kauppila score system based on dual-energy X-ray absorptiometry. We performed stratified analysis and multiple equation regression analysis. R and EmpowerStats were used for data analysis.

RESULTS

A total of 2640 participants were included with the mean AAC score of 1.47 ± 0.07. Participants in higher MDS tended to have higher AAC scores (MDS scored 0: 0.75 (0.56, 0.93), MDS scored 1: 1.02 (0.84, 1.21), MDS scored 2: 2.34 (1.80, 2.87), MDS scored 3: 3.19 (2.46, 3.92), MDS ≥ 4: 4.99 (3.49, 6.49)). Compared with those in the lowest MDS scored 0, the highest subgroup (MDS ≥ 4) was associated with a higher AAC score (β = 4.24, 95% CI: 2.78-5.70, p < 0.001), and the association was not altered (β = 1.81, 95% CI: 0.54-3.09, p = 0.002) after adjusting for numerous covariates. Subgroup analyses showed that stronger associations between MDS and AAC score were detected in adults with lower levels of magnesium intake and older (all p for interaction < 0.05).

CONCLUSIONS

The MDS is a promising tool for identifying individuals with magnesium deficiency status who may benefit from dietary magnesium supplementation to reduce the risks of AAC.