Impact of vitamin D supplementation on markers of bone turnover: Systematic review and meta-analysis of randomised controlled trials.

AIM: The effects of vitamin D administration on bone turnover markers (BTMs) in adults are controversial. Thus, we carried out a meta-analysis of available randomised controlled trials (RCTs) to examine the impact of vitamin D supplementation on BTMs. METHODS: To identify relevant RCTs, we searched the PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library and Embase databases for manuscripts published up to July 2022. The present study was conducted in agreement with the PRISMA guidelines. Weighed mean difference (WMD) and 95% confidence intervals (CI) were used to calculate the magnitude of the effect of the intervention. RESULTS: A total of 42 RCTs were included in the meta-analysis. The age of the participants enrolled in the RCTs ranged from 19.4 to 84 years. The pooled results depicted a decrease in deoxypyridinoline (DPD) concentrations (WMD: -1.58 nmol/mmol, 95% CI: -2.55, -.61, p = .001) following vitamin D supplementation. In addition, subgroup analyses demonstrated that vitamin D administration notably reduced procollagen type I N-terminal propeptide (PINP) levels in individuals aged >50 years and led to a pronounced decrease in alkaline phosphatase (ALP) values when the intervention lasted >12 weeks. No significant effect was observed on other BTMs, for example, collagen type 1 cross-linked C-telopeptide (CTX) and osteocalcin (OC) levels. CONCLUSION: Vitamin D administration decreases DPD, PINP and ALP levels, indicating a reduced bone turnover following the intervention. Other BTMs, for example, CTX or OC values, were not affected by vitamin D prescription. Vitamin D supplementation may exert a positive effect on some important BTMs.

Ketogenic diets, exercise performance, and training adaptations.

PURPOSE OF REVIEW: The ketogenic diet has been proposed as a nutritional strategy in sports. This review was undertaken to provide an overview of the recent literature concerning the effects of ketogenic diet on exercise performance and training adaptations. RECENT FINDINGS: Most recent literature on the ketogenic diet and exercise performance showed no beneficial effects, especially for trained individuals. During a period of intensified training, performance was clearly impaired during the ketogenic intervention, while a diet with high carbohydrates maintained physical performance. The main effect of the ketogenic diet resides in metabolic flexibility, inducing the metabolism to oxidize more fat for ATP resynthesis regardless of submaximal exercise intensities. SUMMARY: The ketogenic diet is not a reasonable nutritional strategy, as it has no advantage over normal/high carbohydrate-based diets on physical performance and training adaptations even when used only in a specific training/nutritional periodization stage.

Ketogenic diet, epilepsy and cognition: what do we know so far? A systematic review.

CONTEXT: Epilepsy is a chronic neurological disorder that has social, cognitive, and psychological consequences to the patient. OBJECTIVE: The effects of the ketogenic diet (KD) in children and adults with pharmacoresistant epilepsy on cognitive function were evaluated in this systematic review. DATA SOURCES: The MEDLINE, Cochrane Library, Scopus, Web of Science, and LILACS databases were searched up to February 2021. STUDY SELECTION AND DATA EXTRACTION: From the 2973 records initially identified, 24 studies were included in the systematic review. These records were screened via PICO criteria, focusing on studies that evaluated the effects of KD on cognitive function of patients with pharmacoresistant epilepsy. RESULTS: Nineteen studies described improvements in cognitive function attributed to KD; improvements were not observed in 2 studies, but neither was aggravation. Contradictory results were reported in 3 studies, depending on the method used to assess cognition. At first glance, cognitive function appears to be associated with the number of seizures, diet effectiveness, amount of carbohydrate ingested, and antiseizure medication used. However, due to the diversity of methods used to assess cognitive function, especially self-perception of cognitive improvement by the patient, it was not possible to confirm this hypothesis. CONCLUSION: It was not possible to confirm if KD itself promotes improvements in cognitive function in patients with pharmacoresistant epilepsy. Certainly, more studies are needed with better methodological quality, larger and more homogeneous samples in relation to epileptic syndrome and clinical aspects of the disease, more rigid monitoring of adherence to the diet, and use of standardized tests for neuropsychological assessment. Systematic Review Registration: PROSPERO registration no. CRD42019129236.

Phase angle association with metabolic profile in adults: A population-based study.

OBJECTIVE: This study assesses the association of the phase angle (PhA) with the metabolic profile in adults of both sexes. METHODS: This is a cross-sectional, population-based study including 949 adults 20 to 59 y of age living in the Viçosa, Minas Gerais, Brazil - urban zone. The PhA was measured based on electrical bioimpedance analysis. The metabolic profile comprised the following components: waist circumference, glucose, high-density lipoprotein cholesterol (HDL-C), non-HDL-C, triglycerides, C-reactive protein, homeostatic model assessment index-insulin resistance (HOMA-IR), serum uric acid, systolic blood pressure, and diastolic blood pressure. Linear regression models (crude and adjusted) were used to determine the association between each independent and dependent variable; statistical significance was analyzed at 5%. RESULTS: Multiple analyses showed that the increase in the values of waist circumference (ß: -0.01; 95%CI: -0.03; -0.01) represented lower values in the PhA. For the glucose, non-HDL-C, triglycerides, CRP, HOMA-IR and uric acid there was no association with PhA in the adjusted models. . CONCLUSION: Low PhA was directly associated with grater values of the waist circumference, even after adjustments were made in the sociodemographic, lifestyle variables and body mass index; this outcome suggests that PhA is a promising cardiometabolic profile biomarker in adults.

Does the relationship between 25-hydroxyvitamin D status and bone mass vary according to skin color in adults? Results of a Brazilian population-based study.

Skin color has been indicated as an important factor in determining serum concentrations of 25-hydroxyvitamin D [25(OH)D], and consequently bone health. However, studies are controversial and scarce for mixed populations. PURPOSE/INTRODUCTION: To analyze the association of 25(OH)D with bone mineral content (BMC) and bone mineral density (BMD); and to investigate the presence of interaction with skin color in Brazilian adults. METHODS: This is a cross-sectional, population-based study conducted with adult individuals (20-59 years) of both genders. Bone health was assessed by dual energy radiological absortometry. Vitamin D status was measured using serum 25(OH)D. Skin color and other variables in the adjusted model were collected using a questionnaire and anthropometric assessment. Associations and interactions were evaluated using linear regression models stratified according to gender. RESULTS: Non-white men with vitamin D deficiency (< 20.0 ng/mL) have less bone mass than those with insufficiency and sufficiency for the femoral neck and hip sites. According to the adjusted regression analysis, the deficient status of 25(OH)D in men was associated with worse bone health for the lumbar spine sites (ß = - 0.1; p = 0.006), femoral neck (ß = - 0.08; p = 0.006), and hip (ß = - 0.08; p = 0.009). No statistically significant associations were observed between 25(OH)D and bone health in women. In addition, no statistical interaction was identified between skin color and vitamin D status in relation to bone health (p > 0.05 for all tests) in either gender and for all bone sites evaluated. CONCLUSION: Deficient vitamin D status is associated with lower bone mass in adults with differences observed according to gender, but not according to skin color.

Phase angle associated with different indicators of health-related physical fitness in adults with obesity.

In obese populations, the exacerbated increase in adipose tissue results in a significant reduction of health-related physical fitness and can affect the phase angle (PhA), a promising health indicator of cell health and integrity. The aim of this study was to investigate the association of PhA with health-related physical fitness indicators in obese adults. This cross-sectional study had a non-probabilistic sample and was conducted from April to June 2018. The PhA was obtained by a bioelectrical impedance analysis, and the health-related physical fitness indicators evaluated were percentage of body fat (%BF), lower- and upper-body maximal strength, cardiorespiratory fitness (relative V̇O2peak), and flexibility. Pearson and Spearman´s linear correlations, crude and adjusted linear regression analyses were performed. A total of 69 obese adults (60.8% female; BMI = 33.5 ± 2.8 kg/m2) with a mean age of 34.6 ± 7.1 years were studied. The PhA means were 5.8 (±0.6º) and had an inverse correlation with %BF (r=-0.74; p<0.001) and positive correlation with V̇O2peak (r=0.50; p<0.001), lower- and upper-body maximal strength (r=0.65; r=0.70; p<0.001, respectively). After adjustment, %BF (ß=-0.065, adjusted R2=0.53; p<0.001), lower- and upper-body maximal strength (ß=0.004; adjusted R2=0.46; p<0.001, and ß=0.024; adjusted R2=0.50; p<0.001, respectively) were predictors of PhA. Our results suggest the favorable role of PhA as a clinically viable tool to screen and identify the physical fitness variables and functional status of obese adults.