Vitamin D Intake and Cardiometabolic: Risk Factors in Adolescents

Background: A growing body of research suggests that vitamin D might play an important role in overall health. No data exist on vitamin D intake for the Azorean adolescent population. The purpose of this study was to assess vitamin D intake and investigate a possible association between vitamin D intake and cardiometabolic risk factors in Azorean adolescents. Methods: A cross-sectional school-based study was conducted on 496 adolescents (288 girls) aged 15–18 years from the Azorean Islands, Portugal. Anthropometric measurements (waist circumference and height), blood pressure (systolic), and plasma biomarkers [fasting glucose, insulin, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TGs)] were measured to assess metabolic risk. Homeostasis model assessment (HOMA), TC-to-HDL-C ratio, and waist-to-height ratio were calculated. For each of these variables, a Z-score was computed by age and sex. A metabolic risk score was constructed by summing the Zscores of all individual risk factors. High risk was considered when the individual had ‡ 1 standard deviation(SD) of this score. Vitamin D intake was assessed with a semiquantitative food frequency questionnaire. Participants were classified into quartiles of vitamin D intake. Logistic regression was used to determine odds ratios for high cardiometabolic risk scores after adjusting for total energy intake, pubertal stage, fat mass percentage, and cardiorespiratory fitness. Results: Mean (SD) vitamin D intake was 5.8 (6.5) mg/day, and 9.1% of Azorean adolescents achieved the estimated average requirement of vitamin D (10 mg/day or 400 IU). Logistic regression showed that the odds ratio for a high cardiometabolic risk score was 3.35 [95% confidence interval (CI) 1.28–8.75] for adolescents in the lowest vitamin D intake quartile in comparison with those in the highest vitamin D intake quartile, even after adjustment for confounders. Conclusion: A lower level of vitamin D intake was associated with worse metabolic profile among Azorean adolescents.

The influence of breakfast and dairy products on dietary calcium and vitamin D intake in postpubertal adolescents and young adults

Background: Given the importance of both calcium and vitamin D for bone health and the high prevalence of vitamin D from around the world, the present study aimed to evaluate calcium and vitamin D intake in a group of healthy Brazilian adolescents and young adults and to examine the influence of breakfast and dairy products in the total intake of these nutrients. Methods: One hundred and sixty adolescents and young adults, aged 1620 years old, from a public school, participated in the present study. Three-day dietary records were used to assess calcium and vitamin D intakes. Serum 25(OH) D levels were measured using a radioimmunoassay kit. The results were expressed as the mean (SD). Results: Only 3.8% of the subjects met the daily adequate intake recommendation for calcium, and none for vitamin D [682.2 (132.2) mg day(-1) and 124.0 (28.0) IU day(-1), respectively]. 25(OH) D serum levels were insufficient in 51.5% and deficient in 9.7% of the individuals [72.5 (22.3) nmol L(-1)]. There was a significant positive correlation between dairy product intake with both calcium and vitamin D (r = 0.597 and r = 0.561, respectively; P = 0.000). Adolescents who ate breakfast had a significant higher mean calcium, vitamin D and dairy product intake than adolescents who did not report this meal. Conclusions: The majority of adolescents and young adults did not consume recommended intakes of calcium and vitamin D and also presented 25(OH) D insufficiency. The results indicate that a regular breakfast and the consumption of dairy products represent important strategies in improving calcium and vitamin D intake in the diet.

Association between pre-diagnostic circulating vitamin D concentration and risk of colorectal cancer in European populations:a nested case-control study

Objective. To examine the association between pre-diagnostic circulating vitamin D concentration, dietary intake of vitamin D and calcium, and the risk of colorectal cancer in European populations. Design Nested case-control study. Setting. The study was conducted within the EPIC study, a cohort of more than 520 000 participants from 10 western European countries. Participants: 1248 cases of incident colorectal cancer, which developed after enrolment into the cohort, were matched to 1248 controls. Main outcome measures. Circulating vitamin D concentration (25-hydroxy-vitamin-D, 25-(OH)D) was measured by enzyme immunoassay. Dietary and lifestyle data were obtained from questionnaires. Incidence rate ratios and 95% confidence intervals for the risk of colorectal cancer by 25-(OH)D concentration and levels of dietary calcium and vitamin D intake were estimated from multivariate conditional logistic regression models, with adjustment for potential dietary and other confounders. Results. 25-(OH)D concentration showed a strong inverse linear dose-response association with risk of colorectal cancer (P for trend <0.001). Compared with a pre-defined mid-level concentration of 25-(OH)D (50.0-75.0 nmol/l), lower levels were associated with higher colorectal cancer risk (<25.0 nmol/l: incidence rate ratio 1.32 (95% confidence interval 0.87 to 2.01); 25.0-49.9 nmol/l: 1.28 (1.05 to 1.56), and higher concentrations associated with lower risk (75.0-99.9 nmol/l: 0.88 (0.68 to 1.13); ≥100.0 nmol/l: 0.77 (0.56 to 1.06)). In analyses by quintile of 25-(OH)D concentration, patients in the highest quintile had a 40% lower risk of colorectal cancer than did those in the lowest quintile (P<0.001). Subgroup analyses showed a strong association for colon but not rectal cancer (P for heterogeneity=0.048). Greater dietary intake of calcium was associated with a lower colorectal cancer risk. Dietary vitamin D was not associated with disease risk. Findings did not vary by sex and were not altered by corrections for season or month of blood donation. Conclusions The results of this large observational study indicate a strong inverse association between levels of pre-diagnostic 25-(OH)D concentration and risk of colorectal cancer in western European populations. Further randomised trials are needed to assess whether increases in circulating 25-(OH)D concentration can effectively decrease the risk of colorectal cancer.

Dietary vitamin D and cancers of the oral cavity and esophagus.

BACKGROUND: Data on the association between vitamin D and upper digestive tract neoplasms are limited. METHODS: In two case-control studies in Italy, we examined the relation between dietary vitamin D intake and squamous cell carcinoma of the esophagus (SCCE; 304 cases) and oral/pharyngeal cancer (804 cases). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by multiple logistic regression. RESULTS: Adjusted ORs for SCCE and oral/pharyngeal cancer were 0.58 (95% CI 0.39-0.86) and 0.76 (95% CI 0.60-0.94), respectively, for the highest tertile of vitamin D intake. Using a reference group of those in the highest tertile of vitamin D who were never/former smokers, ORs were 8.7 (95% CI 4.1-18.7) for SCCE and 10.4 (95% CI 6.9-15.5) for oral/pharyngeal cancer among heavy smokers in the lowest vitamin D tertile; similarly, compared with those in the highest tertile of vitamin D who drank <3 alcoholic drinks/day, corresponding ORs were 41.9 (95% CI 13.7-128.6) for SCCE and 8.5 (95% CI 5.7-12.5) for oral/pharyngeal cancer, among heavy alcohol drinkers in the lowest vitamin D tertile. CONCLUSION: We observed inverse associations between dietary vitamin D intake and risk of SCCE and, perhaps, oral/pharyngeal cancer, which were most pronounced among heavy current smokers and heavy consumers of alcohol.

Prevalence of Vitamin D Insufficiency in Brazilian Adolescents

Background/Aims: Cutaneous sun exposure and dietary vitamin D intake are important determinants of vitamin D status. The objective of the present study was to evaluate the vitamin D status of a group of healthy adolescent students living in Brazil. Methods: One hundred and thirty-six adolescents, 64 boys and 72 girls, aged 16-20 years old, living in a rural town in the state of Sao Paulo, Brazil, participated in this study. Results: The mean dietary vitamin D intake was 140 (120-156) IU/day [3.5 (3.0-3.9) mu g/day]. Only 14.9% of the students met the daily adequate intake recommendation of vitamin D. Only 27.9% practice physical activity outdoors and 17.6% of the adolescents apply sunscreen daily. The mean 25(OH)D concentration was 73.0 (22.0) nmol/l [29.2 (8.8) ng/ml]. Vitamin D insufficiency was observed in 60% of adolescents. Conclusions: The present study suggests that even in a sunny climate like Brazil the prevalence of vitamin D insufficiency in adolescents is high. Most likely this is due to low intakes of vitamin D in this group. Due to the limited extent of natural dietary sources of vitamin D, a policy of vitamin D food fortification should be considered in the future, and in the meantime greater use of vitamin D supplements in this population group should be encouraged to provide the increased amounts of this essential nutrient for optimal health. Copyright (C) 2009 S. Karger AG, Basel

Seasonal changes in Vitamin D-effective UVB availability in Europe and associations with population serum 25-Hydroxyvitamin D

Low vitamin D status is common in Europe. The major source of vitamin D in humans is ultraviolet B (UVB)-induced dermal synthesis of cholecalciferol, whereas food sources are believed to play a lesser role. Our objectives were to assess UVB availability (Jm−2) across several European locations ranging from 35° N to 69° N, and compare these UVB data with representative population serum 25-hydroxyvitamin D (25(OH)D) data from Ireland (51–54° N), Iceland (64° N) and Norway (69° N), as exemplars. Vitamin D-effective UVB availability was modelled for nine European countries/regions using a validated UV irradiance model. Standardized serum 25(OH)D data was accessed from the EC-funded ODIN project. The results showed that UVB availability decreased with increasing latitude (from 35° N to 69° N), while all locations exhibited significant seasonal variation in UVB. The UVB data suggested that the duration of vitamin D winters ranged from none (at 35° N) to eight months (at 69° N). The large seasonal fluctuations in serum 25(OH)D in Irish adults was much dampened in Norwegian and Icelandic adults, despite considerably lower UVB availability at these northern latitudes but with much higher vitamin D intakes. In conclusion, increasing the vitamin D intake can ameliorate the impact of low UVB availability on serum 25(OH)D status in Europe.

Risk Factors for Maternal Vitamin D Deficiency within the United Arab Emirates

Introduction: Vitamin D deficiency during pregnancy is a public health problem and it has been associated with negative pregnancy outcomes for both mothers and infants. Aim: To estimate the prevalence of vitamin D deficiency in pregnant women in the United Arab Emirates (UAE) and to identify the contribution of risk factors to the 25(OH)D levels. Methods: It is a cross-sectional study in which vitamin D levels of 1088 adult pregnant women were assessed. Information on vitamin D intake was available in a sub-sample of 266 women. Results: The mean serum 25(OH)D was 26.2 nmol/L (95% CI 25.2-27.1 range 5-129.1 nmol/L) with 69% of women being vitamin D deficient (<30 nmol/L). In the bivariate analysis, showed that no predictors could have been indicated as no values exceeded significance (p<0.2). Stepwise multiple linear regression analysis could not be applied to identify predictors of vitamin D levels as no values exceeded p=0.2. Conclusion: Due to the high prevalence of vitamin deficiency in UAE, there is an urge for interventions focusing on supplementation, fortification and diet diversity for preventing health consequences during a critical period of development.

Correlates of Vitamin D Status in Healthy Older Adults Living in Miami-Dade and its Association with Non-Skeletal Outcomes: A Cross-Sectional Study

Examining factors that affect vitamin D status in the fast-growing elderly population of Miami-Dade, Florida, is needed. Vitamin D deficiency in older adults has been linked to correlates of disability, including falls and fractures, and cardiovascular disease. The purpose of this study was to determine the proportion of vitamin D insufficient individuals and their relationship with vitamin D insufficiency in older adults (n=97) living in Miami-Dade. We evaluated the association between vitamin D status and 1) dual task physical performance to understand the link between vitamin D and cognition in the context of mobility; and 2) cardiometabolic risk, measured by galvanic skin response, pulse oximetry, and blood pressure to create a composite score based on autonomic nervous system and endothelial function. Participants completed baseline assessments that included serum levels of vitamin D, anthropometrics, body composition, dual task physical performance and cardiometabolic risk. Surveys to evaluate vitamin D intake, sun exposure, physical activity, and depressive symptoms were completed. Spearman’s correlations, independent t-tests, paired t-tests, repeated measures ANOVAs, and multiple logistic and linear regressions were used to examine the relationship of vitamin D insufficiency (25(OH)D /ml) and sufficiency (25(OH)D ≥30 ng/ml) with determinants of vitamin D status, dual task physical performance variables and cardiometabolic risk scores. Although the proportion of vitamin D insufficient individuals was lower when compared to the prevalance of the general United States elderly population, it was still common in healthy community-dwelling older adults living in Miami-Dade County, especially among Hispanics. Factors that affected skin synthesis (ethnicity, and sun exposure), and bioavailability/metabolism (obesity) were significant predictors of vitamin D status. Vitamin D insufficiency was not significantly correlated with worse dual task physical performance; however, cognitive performance was worse in the vitamin D insufficient group. Our results suggest a relationship of vitamin D insufficiency with executive dysfunction, and support an association with cardiometabolic risk using an innovative electro-sensor complex, possibly by modulating autonomic nervous system activity and vascular function, thus affecting cardiac performance.

Effects of usual nutrient intake and vitamin D status on markers of bone turnover in Swiss adolescents.

OBJECTIVE: To evaluate the effects of nutrient intake and vitamin D status on markers of type I collagen formation and degradation in adolescent boys and girls. DESIGN: Cross-sectional study. SETTING: Canton of Vaud, West Switzerland. SUBJECTS: A total of 92 boys and 104 girls, aged 11-16 y. Data were collected on height, weight, pubertal status (self-assessment of Tanner stage), nutrient intake (3-day dietary record) and fasting serum concentration of 25-hydroxyvitamin D (25OHD), and markers of collagen formation (P1NP) and degradation (serum C-terminal telopeptides: S-CTX). RESULTS: Tanner stage was a significant determinant of P1NP in boys and girls and S-CTX in girls. Of the nutrients examined, only the ratio of calcium to phosphorus (Ca/P) was positively associated with P1NP in boys, after adjustment for pubertal status. 25OHD decreased significantly at each Tanner stage in boys. Overall, 15% of boys and 17% of girls were identified as being vitamin D insufficient (serum 25OHD <30 nmol/l), with the highest proportion of insufficiency at Tanner stage 4-5 (29%) in boys and at Tanner stage 3 (24%) in girls. A significant association was not found between 25OHD and either bone turnover marker, nor was 25OHD insufficiency associated with higher concentrations of the bone turnover markers. CONCLUSIONS: The marked effects of puberty on bone metabolism may have obscured any possible effects of diet and vitamin D status on markers of bone metabolism. The mechanistic basis for the positive association between dietary Ca/P ratio and P1NP in boys is not clear and may be attributable to a higher Ca intake per se, a critical balance between Ca and P intake or higher dairy product consumption. A higher incidence of vitamin D insufficiency in older adolescents may reflect a more sedentary lifestyle or increased utilisation of 25OHD, and suggests that further research is needed to define their requirements. SPONSORSHIP: Nestec Ltd and The Swiss Foundation for Research in Osteoporosis.

Vitamin D insufficiency: A risk factor to vertebral fractures in community-dwelling elderly women

Objective:To determine the risk factors for the presence of moderate/severe vertebral fracture, specifically 25-hydroxyvitamin D (25-OHD). Study design: Cross-sectional study conducted for 2 years in the city of Sao Paulo, Brazil including community-dwelling elderly women. Methods: Bone mineral density (BMD), serum 25-OHD, intact parathyroid hormone (iPTH), calcium and estimated glomerular filtration rate (eGFR) were examined in 226 women without vertebral fractures (NO FRACTURE group) and 189 women with at least one moderate/severe vertebral fracture (FRACTURE group). Vertebral fracture assessment (VFA) was evaluated using both the Genant semiquantitative (SQ) approach and morphometry. Results: Patients in the NO FRACTURE group had lower age, increased height, higher calcium intake, and higher BMD compared to those patients in the FRACTURE group (p < 0.05). Of interest, serum levels of 25-OHD in the NO FRACTURE group were higher than those observed in the FRACTURE group (51.73 nmol/L vs. 42.31 nmol/L, p < 0.001). Reinforcing this finding, vitamin D insufficiency (25-OHD < 75 nmol/L) was observed less in the NO FRACTURE group (82.3% vs. 93.65%, p = 0.001). After adjustment for significant variables within the patient population (age, height, race, calcium intake, 25-OHD, eGFR and sites BMD), the logistic-regression analyses revealed that age (OR = 1.09, 95% Cl 1.04-1.14, p < 0.001) femoral neck BMD (OR = 0.7, 95% CI 0.6-0.82, p < 0.001) and 25-OHD <75 nmol/L (OR = 2.38, 95% CI 1.17-4.8, p = 0.016) remains a significant factor for vertebral fracture. Conclusion: Vitamin D insufficiency is a contributing factor for moderate/severe vertebral fractures. This result emphasizes the importance of including this modifiable risk factor in the evaluation of elderly women. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Calcium, vitamin D and cardiovascular disease.

The relationship between calcium and cardiovascular diseases (CVD) has been explored for a long time. Studies exploring the effect of calcium intake or calcium supplementation on cardiovascular risk suggest that systolic blood pressure increases under low calcium intake and decreases with calcium supplementation. A lower calcium intake has been associated with an increased risk of stroke. However, the impact of calcium supplementation on stroke risk remains unclear. Calcium supplementation may increase the risk of myocardial infarction. The relationship between vitamin D and CVD has been explored more recently. Negative correlations between vitamin D levels and the risk of hypertension, myocardial infarction, and stroke have been reported in several observational studies. The effect of vitamin D supplementation on blood pressure is still unclear and no effect of vitamin D supplementation on coronary heart disease or stroke has been clearly demonstrated. There is a lack of randomized clinical trials primarily addressing the effect of these parameters on CVD. Therefore, the real impact of calcium and vitamin D on cardiovascular outcomes remains to be documented by appropriate experimental data.

Vitamin D levels and associated factors: a population-based study in Switzerland.

QUESTIONS UNDER STUDY: To update the prevalence of vitamin D insufficiency and to identify factors associated with vitamin D status in the Swiss adult population. METHODS: Data from the 2010-2011 Swiss Study on Salt intake, a population-based study in the Swiss population, was used. Vitamin D concentration in serum was measured by liquid chromatography- tandem mass spectrometry. Major factors that influence vitamin D levels were taken into account. Survey statistical procedures were used to estimate means and prevalences of vitamin D levels and status. Monthly-specific tertiles of vitamin D and ordinal logistic regression were used to determine the associations of covariates of interest with vitamin D status. RESULTS: The prevalences of vitamin D insufficiency (serum 25-hydroxyvitamin D: 20-29.9 ng/ml) and deficiency (<20 ng/ml) were the highest in the January-March period; 26.4% (95%CI: 21.6-31.7) and 61.6% (95%CI: 56.0-67.0), respectively. In the same period, more than 9 of ten men were vitamin D insufficient or deficient. Each unit increase of Body Mass Index was associated with an 8% decreased likelihood of being in a higher vitamin D tertiles. Oral contraceptive, altitude, urinary excretion of calcium, use of vitamin D supplement or treatment, high wine consumption, physical activity were associated with vitamin D tertiles. Compared to the French-speaking region, the Italian-speaking region was independently associated with a higher likelihood of being in higher vitamin D tertiles (OR: 1.66, 95%CI: 1.14-2.43). CONCLUSIONS: Low levels of vitamin D are common among Swiss adults, in particular during winter months and outside the Italian-speaking region.

Effets des supplémentations en calcium et vitamine D sur la maladie cardiovasculaire. [Effects of calcium and vitamin D supplementations on cardiovascular disease: review article].

Studies exploring the effect of calcium supplementation on cardiovascular risk suggest that systolic blood pressure decreases with supplementation. A lower calcium intake has been associated with an increased risk of stroke. By contrast, calcium supplementation may increase the risk of myocardial infarction. The effect of vitamin D supplementation on blood pressure is still unclear and no effect of vitamin D supplementation on coronary heart disease or stroke has been clearly demonstrated. There is a lack of randomized clinical trials primarily addressing the effect of these parameters on CVD. Currently, the use of calcium and vitamin D supplementations for the prevention of cardiovascular disease is not justified.

Natural vitamin C intake and the risk of head and neck cancer : a pooled analysis in the International Head and Neck Cancer Epidemiology Consortium

Evidence of associations between single nutrients and head and neck cancer (HNC) is still more limited and less consistent than that for fruit and vegetables. However, clarification of the protective mechanisms of fruit and vegetables is important to our understanding of HNC etiology. We investigated the association between vitamin C intake from natural sources and cancer of the oral cavity/pharynx and larynx using individual-level pooled data from ten case-control studies (5,959 cases and 12,248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium. After harmonization of study-specific exposure information via the residual method, adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using unconditional multiple logistic regression models on quintile categories of 'non-alcohol energy-adjusted' vitamin C intake. In the presence of heterogeneity of the estimated ORs among studies, we derived those estimates from generalized linear mixed models. Higher intakes of vitamin C were inversely related to oral and pharyngeal (OR = 0.54, 95% CI: 0.45-0.65, for the fifth quintile category versus the first one, p for trend<0.001) and laryngeal cancers (OR = 0.52, 95% CI: 0.40-0.68, p for trend = 0.006), although in the presence of heterogeneity among studies for both sites. Inverse associations were consistently observed for the anatomical subsites of oral and pharyngeal cancer, and across strata of age, sex, education, body mass index, tobacco, and alcohol, for both cancer sites. The inverse association of vitamin C intake from foods with HNC may reflect a protective effect on these cancers; however, we cannot rule out other explanations.

Vitamin E intake from natural sources and head and neck cancer risk : a pooled analysis in the International Head and Neck Cancer Epidemiology consortium.

BACKGROUND: Evidence for the possible effect of vitamin E on head and neck cancers (HNCs) is limited. METHODS: We used individual-level pooled data from 10 case-control studies (5959 cases and 12 248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium to assess the association between vitamin E intake from natural sources and cancer of the oral cavity/pharynx and larynx. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression models applied to quintile categories of nonalcohol energy-adjusted vitamin E intake. RESULTS: Intake of vitamin E was inversely related to oral/pharyngeal cancer (OR for the fifth vs the first quintile category=0.59, 95% CI: 0.49-0.71; P for trend <0.001) and to laryngeal cancer (OR=0.67, 95% CI: 0.54-0.83, P for trend <0.001). There was, however, appreciable heterogeneity of the estimated effect across studies for oral/pharyngeal cancer. Inverse associations were generally observed for the anatomical subsites of oral and pharyngeal cancer and within covariate strata for both sites. CONCLUSION: Our findings suggest that greater vitamin E intake from foods may lower HNC risk, although we were not able to explain the heterogeneity observed across studies or rule out certain sources of bias.