Vivek Patwardhan

Varying relationship between 25-hydroxy-vitamin D, high density lipoprotein cholesterol, and serum 7-dehydrocholesterol reductase with sunlight exposure.

BACKGROUND Cholesterol and cholecalciferol are synthesized from a common substrate 7-dehydrocholesterol. 7-dehydrocholesterol is converted to cholesterol by 7-dehydrocholesterol reductase enzyme (DHCR7) and to cholecalciferol by ultraviolet B radiation from sunlight. OBJECTIVE To examine the effect of sunlight exposure and serum DHCR7 levels on cholecalciferol and cholesterol levels and studying any interrelationship. METHODS In a cross-sectional observational study, 307 apparently healthy men (aged 40-60 years) were assessed for sunlight exposure, lipid levels, serum DHCR7, 25 hydroxyvitamin D (25(OH)D), body composition, and dietary milk calcium intake. RESULTS Vitamin D deficiency (25(OH)D <20 ng/mL, 1 ng/mL = 2.496 nmols/L) was found in 56% of subjects. Serum 25(OH)D concentrations increased significantly with increasing duration of sunlight exposure (P < .05). At lower sunlight exposure (<1 h/d), serum 25(OH)D levels were positively associated with high-density lipoprotein cholesterol (HDL-C) levels (P < .05) but at moderate sunlight exposure (1-2 h/d), there was no significant association. However, with higher sunlight exposure (>2 h/d), serum 25(OH)D concentrations were significantly negatively associated with HDL-C (P < .05). At moderate and higher sunlight exposure, an inverse significant relationship was observed between 25(OH)D and serum DHCR7 (P < .05); however, at lower sunlight exposure, no significant relationship was seen. CONCLUSIONS 25(OH)D seems to show a varying relationship with HDL-C and serum DHCR7 at different durations of sunlight exposure.

Reference centile curves for triceps skinfold thickness for Indian children aged 5–17 years and cut-offs for predicting risk of childhood hypertension: A multi-centric study

ObjectivesTo create age- and gender-specific Triceps Skinfold Thickness percentile curves for Indian children; and to determine cut-offs for predicting the risk of childhood hypertension.DesignCross-sectional.SettingMulticentric, school-based, 5 major Indian citiesParticipants13375 children (7590 boys) aged 5-17 yearsProcedureData on height, weight, blood pressure, triceps skinfold thickness (using Harpenden Skinfold caliper) were collected. Reference triceps skinfold thickness percentile curves were derived for boys and girls by LMS (lambda-mu-sigma) method. Receiver operating curve analyses were performed to determine the optimal cut-off of triceps skinfold thickness centile for predicting the risk of hypertension.ResultsPercentile curves for boys plateau around 13 years whereas for girls the curves increase steadily till the age of 17 years. Median triceps skinfold thickness increased by 7% to 9% till the age of 9 years in boys and girls. After 12 years, median triceps skinfold thickness decreased by 1% to 2% in boys but increased by 3% to 4% in girls. The optimal cut-off percentile yielding maximal sensitivity (68%) and specificity (74-78%) for predicting high blood pressure was the 70th triceps skinfold thickness percentile in both genders.ConclusionsPercentile curves for triceps skinfold thickness developed in the present study would be useful in the assessment of adiposity and the risk of hypertension in Indian children.

Randomized control trial assessing impact of increased sunlight exposure versus Vitamin D supplementation on lipid profile in Indian Vitamin D deficient men

Background: Despite abundance of sunshine in India, Vitamin D deficiency is common and therefore there is an increasing trend toward taking Vitamin D supplements either as prescription medicine or as a nutritional supplement. Studies have suggested that duration of sun exposure may influence serum lipid profile. Objectives: To study the effect of increased sunlight exposure versus Vitamin D supplementation on Vitamin D status and lipid profile in individuals with Vitamin D deficiency (25-hydroxyvitamin-D [25OHD] <50 nmol/L). Design: A prospective, randomized open-label trial was carried out in apparently healthy Indian men (40–60 years). Based on 25OHD concentrations, individuals were divided into control (>50 nmol/L, n = 50) and intervention (<50 nmol/L, n = 100) groups. Individuals from intervention group were randomly allocated to two groups; either “increased sunlight exposure group” (n = 50, received at least 20 min sunlight exposure to forearms and face between 11 a.m. and 3 p.m. over and above their current exposure) or “cholecalciferol supplement group” (n = 50, received oral cholecalciferol 1000 IU/day). Results: Significant increase in 25OHD concentrations was seen in both intervention groups (P < 0.01). Significant decrease in total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C), and low-density-lipoprotein cholesterol (LDL-C) was seen in individuals with increased sunlight exposure (P < 0.05). Cholecalciferol supplement group showed a significant increase in TC and HDL-C (P < 0.05) and insignificant increase in LDL-C. Conclusions: Increase in Vitamin D concentrations through sunlight exposure significantly reduced TC, LDL-C, and HDL-C concentrations, and cholecalciferol supplementation increased TC and HDL-C concentrations.

Response of serum 25(OH)D to Vitamin D and calcium supplementation in school-children from a semi-rural setting in India

The objectives of this study were to: 1) Determine the impact of varying baseline serum 25OHD on increase in vitamin D concentrations after daily supplementation with vitamin D and calcium (1000 IU + 500 mg respectively) for six months in school-children from a semi-rural setting 2) Test the efficacy of daily vitamin D-calcium supplementation on improvement in serum vitamin D concentrations to ≥75 nmol/L. Data collected from 106 subjects (58 boys, 48 girls), aged 6-12 years, included anthropometric measures like height and weight, body composition analysis, three one-day dietary recalls and sunlight exposure (by questionnaire). Blood was collected at baseline and endline and estimated for serum vitamin D by ELISA technique using standard kits. Classification of Vitamin D status was performed according to the 2011 Endocrine Society Practice Guidelines: vitamin D deficiency - <50 nmol/L; insufficiency - 50.0-74.9 nmol/L; sufficiency - ≥75 nmol/L. Statistical analysis was performed using SPSS software. Mean baseline serum vitamin D concentration was 59.7 ± 11.2 nmol/L; this rose to 79.8 ± 23.3 nmol/L with no significant differences between genders at the two time-points. Inverse relationship was obtained between baseline serum 25(OH)D concentrations and change in serum concentrations after supplementation, implying that with increasing baseline serum concentrations of 25(OH)D, increase in vitamin D levels post supplementation were significantly lower (r = - 0.96, p < 0.0001). Greatest benefit of change in serum vitamin D concentrations after supplementation was experienced by children with basal concentrations of <45 nmol/L. Daily vitamin D supplementation was effective in improving serum 25(OH)D to ≥75 nmol/L in 44% of children. Significantly higher percentage of children who were deficient at baseline (64%) were able to attain serum concentrations of ≥75 nmol/L as compared to children who were vitamin D insufficient (43%) (p < 0.001). Thus, daily supplementation with 1000 IU of vitamin D along with 500 mg of calcium helped in improving serum vitamin D concentrations to ≥75 nmol/L. Children who were vitamin D deficient particularly experienced these benefits.

Association of dental and skeletal fluorosis with calcium intake and serum vitamin D concentration in adolescents from a region endemic for fluorosis

Context: Fluorosis is controlled by the duration of fluoride exposure and calcium and Vitamin D nutrition status. Aim: To examine (a) prevalence of dental and skeletal fluorosis in adolescents from upper, middle, and lower socioeconomic strata (SES) and (b) association of fluorosis with calcium intake and Vitamin D status. Settings and Design: A cross-sectional study conducted in 10–13.9 years apparently healthy adolescents (n = 90), from different SES of Patan (Gujarat, India). Materials and Methods: Dental fluorosis was graded as mild, moderate, and severe. Radiographs of the right hand and wrist were examined and graded. Serum 25 hydroxyvitamin D3 (25OHD) and parathyroid hormone concentrations were measured. Diet was recorded (24 h recall) and calcium intake was computed (C-diet V-2.1, 2013, Xenios Technologies Pvt. Ltd). Statistical Analysis: Generalized linear model was used to analyze relationships between fluorosis, SES, serum 25OHD concentration, and calcium intake. Results: Fluorosis was predominant in lower SES (17% had both dental and radiological features whereas 73% had dental fluorosis); no skeletal deformities were observed. Mean 25OHD concentrations and dietary calcium were 26.3 ± 4.9, 23.4 ± 4.7, and 18.6 ± 4 ng/ml and 441.2 ± 227.6, 484.3 ± 160.9, and 749.2 ± 245.4 mg/day, respectively, for lower, middle, and upper SES (P < 0.05). Fluorosis and SES showed a significant association (exponential β = 2.5, P = 0.01) as compared to upper SES, middle SES adolescents were at 1.3 times while lower SES adolescents were at 2.5 times higher risk. Serum 25OHD concentrations (P = 0.937) and dietary calcium intake (P = 0.825) did not show a significant association with fluorosis. Conclusion: Fluorosis was more common in lower SES adolescents, probably due to the lack of access to bottled water. Relatively adequate calcium intake and serum 25OHD concentrations may have increased the efficiency of dietary calcium absorption, thus preventing severe fluorosis.

Relationship of insulin-like growth factor 1 and bone parameters in 7–15 years old apparently, healthy Indian children

Objective: Growth hormone through insulin-like growth factor 1 (IGF-1) plays an important role in both bone growth and mineralization. This cross-sectional study was carried out to evaluate the relationship between serum IGF-1 concentrations and dual energy X-ray (DXA) measured whole body less head bone area (BA), lean body mass (LBM), and bone mineral content (BMC). Methods: One hundred and nineteen children (boys = 70, age = 7.3–15.6 years) were studied for their anthropometric parameters by standard methods and bone and body composition by DXA. Their fasting serum IGF-1 concentrations were assessed by enzyme-linked immunosorbent assay and Z-scores were calculated using available reference data. Bone and body composition parameter Z-scores were calculated using ethnic reference data. Results: Mean age of the boys and girls was similar (11.5 ± 1.8 years). The mean serum IGF-1concentrations and IGF-1 Z-scores were similar (P > 0.1) between boys and girls and were of the order of (302.3 ± 140.0 and − 1.4 ± 1.1, respectively). The LBM for age and BA for age Z-score was greater in children with IGF-1 Z-score > median than children with IGF-1 Z-score < median. The mean BMC for age Z-scores were 0.4 ± 0.9 and − 0.2 ± 0.8 in children with above and below the median of IGF-1 Z-score (P > 0.1). Conclusion: Serum IGF-1 levels were more strongly associated with BA and LBM, suggesting that its effect on bone is greater with respect to periosteal bone acquisition and through its effect on muscle mass.

Duration of casual sunlight exposure necessary for adequate Vitamin D status in Indian Men

Objectives: To investigate the duration of casual sunlight ultraviolet-B (UVB) exposure required to maintain optimal Vitamin D status (25-hydroxyvitamin-D [25(OH)D]) >50 nmol/L in urban Indian men, using polysulfone (PSU) dosimeters and a sunlight exposure questionnaire. Methods: In healthy men (aged 40–60 years) from Pune (18.52° N, 73.86° E), India, serum 25(OH)D was measured using enzyme-linked immunosorbent assay. Sunlight exposure was assessed using PSU dosimeter and by questionnaire. Results: Of 160 men (48.3 ± 5.6 years), 26.8% were deficient and 40.6% had insufficient Vitamin D concentrations. A hyperbolic function for the relationship between PSU measured sunlight exposure in standard erythema dose (SED) and serum 25(OH)D concentrations (r = 0.87, P < 0.01) revealed that daily exposure of 1 SED was sufficient to maintain serum 25(OH)D concentrations over 50 nmol/L. The curve plateaued around 5 SED (80 nmol/L) and extrapolation of the curve (>5 SED) did not increase 25(OH)D concentrations above 90 nmol/L. Receiver operating curve analysis confirmed that 1 SED-UV exposure was sufficient to maintain 25(OH)D concentrations over 50 nmol/L. Based on the questionnaire data, >1 h of midday casual sunlight exposure was required to maintain serum 25(OH)D concentrations above 50 nmol/L. Duration of sunlight exposure assessed by questionnaire and PSU dosimeter showed a significant correlation (r = 0.517, P < 0.01). Conclusion: In urban Indian men, >1 h of casual midday sunlight exposure daily was required to maintain serum 25(OH)D concentrations above 50 nmol/L, and >2 h of casual sunlight exposure was needed to maintain 25(OH)D concentrations above 75 nmol/L. Excess sunlight did not increase 25(OH)D linearly. The sunlight exposure questionnaire was validated for use in clinical studies and surveys.

Determinants of Vitamin D status in Indian school-children

Introduction: Due to the high prevalence of Vitamin D deficiency in spite of abundant sunshine and scarcity of studies investigating Vitamin D status in Indian children from rural and semirural areas, the objectives of this cross-sectional study were to: (1) assess the Vitamin D status of school-children in a semi-rural setting and (2) identify the determinants of Vitamin D status in these children. Materials and Methods: Data collected included anthropometric measurements (height and weight), body composition, three-one-day dietary recall method, demographic data, and sunlight exposure. Serum 25-hydroxyVitamin D (25(OH)D) was estimated by enzyme-linked immunosorbent assay (ELISA) technique. SPSS software was used for statistical analysis. Results: Anthropometric characteristics of the children were similar and mean serum 25(OH)D concentration was 58.5 ± 10.3 nmol/L with no significant differences between genders. Around 80% children reported sunlight exposure of 2 h or more. A majority (71%) of children were Vitamin D insufficient with serum 25(OH)D concentrations between 50 and 74.9 nmol/L. Determinants of Vitamin D identified were duration of sunlight exposure and body fat percent. Significant (P < 0.05) positive association of duration of sunlight exposure was observed with serum 25(OH)D concentrations, while BF% showed a negative association with serum 25(OH)D (β = –0.307; standard error = 0.1388; P < 0.05). Discussion: We have reported a high prevalence of Vitamin D insufficiency in school-children aged 6–12 years, from a semirural setting, in spite of a majority (80%) reporting >2 h of sunlight exposure. We have also demonstrated that duration of sunlight exposure and body fat percentage are the two important determinants of serum 25(OH)D concentrations in these children.

Interrelationship between serum 25-hydroxyvitamin D3 concentration and lipid profiles in premenopausal Indian women

Context: Vitamin D deficiency is prevalent worldwide, and observational studies have associated it with an atherogenic lipid profile. Aim: To determine the interrelationship between Vitamin D and lipid profile in apparently healthy premenopausal Indian women, considering confounding factors such as lifestyle that independently influence lipids. Setting and Design: Cross-sectional study. Subjects and Methods: One hundred and twenty healthy premenopausal women (20–45 year) were recruited from Gujarat, India. Data were collected on anthropometry, physical activity, sunlight exposure, and diet. Fasting blood samples were collected for the measurement of serum 25-hydroxyvitamin D3 (25[OH]D), parathyroid hormone, and lipid profile. Statistical Analysis: Pearsons correlation coefficient was used to derive correlation between serum 25(OH)D concentrations and serum lipids. Results: Ninety-three percent women showed Vitamin D deficiency (serum 25[OH]D < 20 ng/ml). Serum 25(OH)D concentrations showed significant inverse correlation with total cholesterol (TC) (r = −0.202, P = 0.027), triglycerides (TG) (r = −0.284, P = 0.002), and low-density lipoprotein-cholesterol (LDL-C) (r = −0.184, P = 0.044) and positive correlation with high-density lipoprotein-cholesterol (HDL-C) (r = 0.250, P = 0.006). On dichotomizing the population according to median 25(OH)D concentration (11.1 ng/dl), no significant differences were observed between the groups for anthropometry, sunlight exposure, and lifestyle. Serum lipid profiles were significantly different, above median serum 25(OH)D concentration group showed favorable serum lipids (TC: 179.3 ± 30 vs. 191.8 ± 31.7 mg/dl; TG: 140 ± 39.1 vs. 165.5 ± 53.4 mg/dl; LDL-C: 100 ± 30.2 vs. 112 ± 32 mg/dl; HDL-C: 53 ± 14 vs. 47.6 ± 9.3 mg/dl)(P < 0.05). Conclusions: This study demonstrates that association of 25(OH)D concentrations with lipid profile even after considering lifestyle factors which independently influence lipids. Intervention trials would be required to prove this association to be causation.