Vitamin D Association with Renal Health and Filtration in Healthy Individuals Free of Cardiometabolic Diseases: A Pilot Study

The effect of vitamin D (VITD) on bone, muscle, and over health is well know in renal failure and chronic kidney disease (CKD). However, the influence of VITD on renal health and filtration (RHF) in healthy individuals is unclear. Currently, only serum creatinine concentration (sCr) methods are used to assess renal status in health individuals. However, newer biomarkers like serum Cystatin C (CyC) and urine epidermal growth factor (uEGF) show promise in evaluating baseline RHF. The impact of Vitamin D on filtration in healthy individuals of various ages is still unknown. PURPOSE: To determine the impact of VITD on RHF in healthy individuals of middle-aged status. METHODS: Thirty-six participants (n = 22 men; n = 14 women; age 37.6 + 12.4 yr; BF% 19.2 + 7.1%) agreed to participate in the research study. Blood and urine samples were obtained under standardized conditions for all individuals. VITD, CyC, uEGF, urine creatinine (uCr), uCr/uEGF ratio, sCR, and multiple estimates of glomerular filtration rate (eGFR) - modification of diet in renal disease (MDRD), CKD-EPI, CyC equations (CyC only and CyC combined with sCr) were assessed as a whole cohort and grouped (young = 20-39 yrs. (n = 22), older = 40-60 yrs. (n = 14)). Analysis was done using a paired sample t-tests, Pearson Correlation to compare VITD concentrations and markers of RHF. Linear regression analyses was performed to examine the relationship between VITD ability to predict RHF. All analyses were performed using SPSS (v. 28.0.1.1). RESULTS: There was no significant correlations found between VITD and markers of RHF in the entire cohort. Therefore, no predictive model was performed. The younger group showed strong negative correlation between VITD and MDRD (r = -0.575, p = 0.008), and that VITD was able to predict MDRD (R2 = 0.331, p = 0.008). No significant correlation observed in older group. CONCLUSIONS: VITD was correlated and able to predict a marker of RHF in healthy younger individuals, but not in older individuals. Based on the sample size and overall outcomes, continued research is needed to more accurately determine VITD effects on RHF in healthy populations

The Influence of High-Intensity Interval Exercise on Vitamin-D Concentrations in Healthy Individuals

Vitamin D (VD) deficiency is one of the most common deficiencies in the world due to various factors (e.g., lack of sun exposure, dietary considerations). Currently the utilization of exercise may act as an intervention for VD deficiencies to promote increases in VD concentrations in healthy populations. This could largely be due to the loss of calcium from aerobic exercise (AE), leading to a hormonal response [(e.g., parathyroid hormone (PTH)] and the activation of cytochrome’s (e.g., CYP2R1, CYP27B1) responsible for the regulation of VD. Thus, AE may serve as an intervention to promote VD synthesis due to the impacted biological mechanisms placed upon the body. PURPOSE: To determine changes in VD concentrations in healthy individuals, following an acute bout of HIIE. METHODS: Thirty-five apparently heathy and physically active individuals (22 = M and 14 = F, age = 37.7 ± 12.6, %BF = 19.3 ± 7.0) were recruited for participation in the study. All participants completed an initial testing session where measures of body composition, health status, and cardiorespiratory fitness [(VO2Reserve (VO2R)] were assessed using standardized protocols. Following baseline assessments, participants returned to the lab 48-HR later to perform one bout of HIIE for 30-minutes on a treadmill. Participants completed six high- and low-intensity stages, with each stage consisting of 3-minute intervals of submaximal exercise at 80% VO2R and 2-minute recovery intervals at 40% VO2R. Venous blood samples were obtained at three-time points (e.g., pre-exercise, 1-HR post-exercise, 24-HR post-exercise) from the most prominent antecubital vein. Data were analyzed using a paired samples t-test to assess differences between VD concentrations at the sampled time points. RESULTS: Significant differences were observed between the three-time points. VD concentrations significantly increased from pre-exercise to 1-HR (t = -14.372, p \u3c .001) and 24-HR post-exercise (t = -9.468, p \u3c .001). However, VD concentrations were not significantly different from 1-HR to 24-HR post-exercise (t = 0.728, p = .471). CONCLUSION: HIIE could be utilized as a potential intervention to improve VD concentrations in healthy individuals. Future research should examine the effects of HIIE in individuals with VD deficiencies to assess its role in promoting VD synthesis