Dietary Calcium Intake and Osteoporosis Risk in Arab Adults.

Osteoporosis is a major public health concern in Saudi Arabia's aging population. There is particularly limited information on how diet affects bone loss in this ethnic group. The purpose of this study was to examine the association between dietary calcium (Ca) intake and osteoporosis risk in Saudi adults. A total of 1950 patients (416 males and 1534 females) with known risk factors for osteoporosis participated in this cross-sectional study. A short questionnaire (CaQ) was used to assess dietary Ca intakes in patients attending tertiary hospitals in Riyadh City. The prevalence of osteoporosis was 21.3% and was more common in females (93.5%). Patients with osteoporosis were older (p < 0.001) and had lower BMI (p < 0.001). Results showed that the overall mean Ca intake was only 445.1 mg/day (recommended dietary intake of 1300 mg/day). Tea intake (OR = 0.8 95%CI: 0.7-1.0; p = 0.02) and consumption of fish and eggs (OR = 0.9 95%CI: 0.8-1.0; p = 0.01) were significantly associated with a lower risk of osteoporosis. Furthermore, consumption of biscuits, cake and bread slices were significantly associated with higher incidence of osteoporosis (OR = 1.3 95%CI: 1.0-1.5; p = 0.02). In conclusion, extremely low dietary Ca intake was observed among Saudi adults already at risk of osteoporosis. A balanced diet including high amount of Ca, vitamin D and omega-3 fatty acids accompanied by limiting consumption of foods high in saturated fats and glycemic index may be helpful in reducing osteoporosis risk in the Saudi adult population.

Evidence That Increasing Serum 25(OH)D Concentrations to 30 ng/mL in the Kingdom of Saudi Arabia and the United Arab Emirates Could Greatly Improve Health Outcomes.

Accumulating evidence supports the potential protective effects of vitamin D against chronic diseases such as Alzheimer's disease, autoimmune diseases, cancers, cardiovascular disease (ischaemic heart disease and stroke), type 2 diabetes, hypertension, chronic kidney disease, stroke, and infectious diseases such as acute respiratory tract diseases, COVID-19, influenza, and pneumonia, as well as adverse pregnancy outcomes. The respective evidence is based on ecological and observational studies, randomized controlled trials, mechanistic studies, and Mendelian randomization studies. However, randomized controlled trials on vitamin D supplementation have largely failed to show benefits, probably due to poor design and analysis. In this work, we aim to use the best available evidence on the potential beneficial effects of vitamin D to estimate the expected reduction in incidence and mortality rates of vitamin D-related diseases in the Kingdom of Saudi Arabia and the United Arab Emirates if minimum serum 25(OH)D concentrations were to be raised to 30 ng/mL. Estimated reductions by 25% for myocardial infarction incidence, 35% for stroke incidence, 20 to 35% for cardiovascular disease mortality, and 35% for cancer mortality rates depicted a promising potential for raising serum 25(OH)D. Methods to increase serum 25(OH)D concentrations at the population level could include food fortification with vitamin D3, vitamin D supplementation, improved dietary vitamin D intake, and sensible sun exposure.

Impact of Vitamin D Status Correction on Serum Lipid Profile, Carboxypeptidase N and Nitric Oxide Levels in Saudi Adults.

This study aimed to determine the impact on the lipid profile, carboxypeptidase N (CPN) and nitric oxide (NOx) associated with vitamin D (VD) status correction among Saudi adults with VD deficiency. A total 111 VD deficient (25(OH)D < 50 nmol/L)) adult Saudis aged 18-50 years old (57 females and 54 males) were enrolled in this 6-month interventional study. They were given 50,000 IU VD weekly for the first 2 months and then twice a month for the next 2 months, followed by 1000 IU daily for the last 2 months. The fasting lipid profile and the blood glucose, VD, NOx and CPN concentrations were measured at baseline and after intervention. Post-supplementation, the median VD was significantly higher (p < 0.001) in females [58.3 (50.6-71.2)] and males [57.8 (51.0-71.8)]. HDL cholesterol significantly increased (p = 0.05) and NOx significantly decreased (p = 0.02) in males post-supplementation. Triglycerides were positively associated with NOx in all subjects before (r = 0.44, p = 0.01) and after (r = 0.37, p = 0.01) VD status correction. There was a significant increase in serum levels of CPN2 (p = 0.02) in all subjects. Furthermore, CPN was inversely correlated with NOx (r = -0.35, p = 0.05) in males post-supplementation. In conclusion, VD status correction reduced serum NOx, particularly in males. The inhibition of NOx synthesis may be responsible for the anti-inflammatory effects of VD supplementation. An inverse association was found between NOx and CPN2.

Vitamin D Knowledge and Awareness Is Associated with Physical Activity among Adults: A Cross-Sectional Survey.

The relation between knowledge and awareness of vitamin D (VD) and physical activity in adults has not been well studied. The present cross-sectional study aims to demonstrate this relation among adults living in Saudi Arabia. A total of 774 adults participated and were stratified based on self-reports of whether they were physically active (PA group, N = 562) or not (non-PA, N = 212). The prevalence of VD awareness and its health effects were significantly higher in the PA group compared with their counterparts (97 vs. 93.4%; p = 0.02 and 92.3 vs. 81.6%; p < 0.001, respectively). Sunlight was the preferred overall source of VD among the PA group (91.1%) followed by food, supplements, and fortified foods. Sardine, salmon, oily fish (63.7%) and eggs (54.6%) were reported as good dietary sources. Other positive attitudes, represented by taking supplement or multivitamins (51.2%), high sun exposure (33.1%), and daily duration of exposure to sunlight (15−30 min; 53.4%) were higher in the PA than the non-PA group (p values < 0.05). The body parts exposed to the sun among the PA group were arms (67.1%), hands (64.1%), face and hands (62.5%), legs (58.5%), and face (53.2%), while sunscreen cream (47.2%) was their preferred sun-protection method. High levels of knowledge and positive attitudes were reported by the PA group compared with the non-PA group in regard to walking outdoors for sun exposure (80.6 vs. 62.7%; p < 0.001). Information about good dietary sources, the role of VD in human health, associated diseases, positive attitudes to sun exposure, and the use of supplements or multivitamins were among the determinants of VD knowledge and awareness. In conclusion, VD knowledge and awareness are positively associated with self-reported physical activity in adults. Further objective classifications of PA may strengthen the results of the present investigation.

Patterns of essential trace elements (Cr, Mn, Ni, and Se) in Saudi patients with type 2 diabetes mellitus.

OBJECTIVES: Type 2 diabetes mellitus (T2DM) outcomes were observed to be influenced by circulating trace elements' status. The differences and correlations between serum levels of chromium (Cr), manganese (Mn), nickel (Ni), and selenium (Se) in Saudi patients with and without T2DM as well as those with prediabetes (pre-DM) were examined in this retrospective cross-sectional study. METHODS: Anthropometrics and fasting blood samples were collected from 119 patients with T2DM (aged 41-64 years), 95 non-T2DM (aged 27-55 years), and 80 with pre-DM (aged 35-57 years). An inductively coupled plasma-mass spectrometer was used to measure trace minerals in the blood. RESULTS: T2DM patients had significantly lower Mn serum concentrations than controls. There was no difference in Cr and Ni levels between groups. Serum Mn and Ni levels were lower in pre-DM subjects than controls. Serum Se concentrations were higher in pre-DM and T2DM patients than controls. In T2DM patients, serum Cr and Mn levels were inversely correlated with glucose, while Ni and Se levels were positively correlated with glucose in the T2DM group. CONCLUSIONS: Because of their roles in glucose metabolism, impaired trace element status may also play a role in T2DM pathogenesis. Appropriate dietary control and mineral supplementation are recommended.

Angiogenin Levels and Their Association with Cardiometabolic Indices Following Vitamin D Status Correction in Saudi Adults.

Angiogenin (ANG), a multifunctional protein known to induce blood vessel formation, is a potential biomarker for cardiovascular diseases; however, whether it is affected by vitamin D supplementation is not known. This interventional study in vitamin D-deficient Saudi adults was designed to investigate it. A total of 100 vitamin D-deficient Saudi adults aged 30-50 years were randomly selected to undergo 6-month vitamin D supplementation. Circulating levels of fasting glucose, lipids, vitamin D, apolipoproteins (AI, AII, B, CI, CII, CIII, E, and H), and ANG were measured using commercially available assays at baseline and after six months. Overall, vitamin D levels increased significantly post intervention. With this, levels of apo-CIII and apo-E significantly increased (p-values of 0.001 and 0.009, respectively) with a significant parallel decrease in apo-B (p = 0.003). ANG levels were significantly positively associated with most apolipoproteins and inversely correlated with HDL-cholesterol. Post intervention, the changes in ANG levels were positively correlated with apo-E (r = 0.32; p < 0.01 in all subjects and r = 0.40; p < 0.05 in males). Vitamin D supplementation may modestly affect ANG levels. The association observed between ANG and apo-E is worthy of further investigation since both biomarkers have been linked to neurodegenerative disorders.

Effects of a 2-Week 5000 IU versus 1000 IU Vitamin D3 Supplementation on Recovery of Symptoms in Patients with Mild to Moderate Covid-19: A Randomized Clinical Trial.

OBJECTIVE: Vitamin D deficiency has been associated with an increased risk of COVID-19 severity. This multi-center randomized clinical trial aims to determine the effects of 5000 IU versus 1000 IU daily oral vitamin D3 supplementation in the recovery of symptoms and other clinical parameters among mild to moderate COVID-19 patients with sub-optimal vitamin D status. STUDY DESIGN AND SETTING: A total of 69 reverse transcriptase polymerase chain reaction (RT-PCR) SARS-CoV-2 positive adults who were hospitalized for mild to moderate COVID-19 disease were allocated to receive once daily for 2 weeks either 5000 IU oral vitamin D3 (n = 36, 21 males; 15 females) or 1000 IU oral vitamin D3 (standard control) (n = 33, 13 males; 20 females). Anthropometrics were measured and blood samples were taken pre- and post-supplementation. Fasting blood glucose, lipids, serum 25(OH)D, and inflammatory markers were measured. COVID-19 symptoms were noted on admission and monitored until full recovery. RESULTS: Vitamin D supplementation for 2 weeks caused a significant increase in serum 25(OH)D levels in the 5000 IU group only (adjusted p = 0.003). Within-group comparisons also showed a significant decrease in BMI and IL-6 levels overtime in both groups (p-values < 0.05) but was not clinically significant in between-group comparisons. Kaplan-Meier survival analysis revealed that the 5000 IU group had a significantly shorter time to recovery (days) than the 1000 IU group in resolving cough, even after adjusting for age, sex, baseline BMI, and D-dimer (6.2 ± 0.8 versus 9.1 ± 0.8; p = 0.039), and ageusia (loss of taste) (11.4 ± 1.0 versus 16.9 ± 1.7; p = 0.035). CONCLUSION: A 5000 IU daily oral vitamin D3 supplementation for 2 weeks reduces the time to recovery for cough and gustatory sensory loss among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms. The use of 5000 IU vitamin D3 as an adjuvant therapy for COVID-19 patients with suboptimal vitamin D status, even for a short duration, is recommended.

Dietary Intake and Supplement Use Among Saudi Residents during COVID-19 Lockdown.

Healthy diet and supplement use may prove as sustainable strategies to lower COVID-19 infection. Our study investigated the dietary changes before and during lockdown and observed dietary supplements (DS) use among residents in Saudi Arabia. This cross-sectional study collected data via an online electronic survey questionnaire among males (N = 921) and females (N = 1044) residing in Saudi Arabia, 15 years of age and above. There was a significant decrease in the prevalence of males (before vs. during lockdown) having improved changes in dietary habit (68.6% vs. 65.8%; p = 0.004), which was similar in female participants (69 vs. 73.4% vs. 69%; p < 0.001). The frequency of multivitamin users among COVID-19 participants was significantly lower than non-users (44.4 vs. 55.6; p < 0.003). Male respondents within 26-35 years of age were more likely to use multivitamin supplements than females (30.1 vs. 22.6%; p < 0.05) of same age group. Predictors for DS use were increased age group, income, education level and COVID-19 status. In conclusion, an increase in unhealthy diet behavior was observed among Saudi males and females during the pandemic lockdown and the predictors of DS use included increased age, income, education level and COVID-19 status.

Vitamin D status of Arab Gulf residents screened for SARS-CoV-2 and its association with COVID-19 infection: a multi-centre case-control study.

OBJECTIVES: Vitamin D status in patients with COVID-19 is an on-going controversial issue. This study aims to determine differences in the serum 25(OH)D concentrations of Arab Gulf adult residents screened for SARS-CoV-2 and its association with risk of COVID-19 infection together with other comorbidities. METHODS: In this multi-center, case-control study, a total of 220 male and female adults presenting with none to mild symptoms were screened for COVID-19 (n = 138 RT-PCR-confirmed SARS-CoV-2 positive and 82 negative controls). Medical history was noted. Anthropometrics were measured and non-fasting blood samples were collected for the assessment of glucose, lipids, inflammatory markers and serum 25(OH)D concentrations. RESULTS: Serum 25(OH)D levels were significantly lower in the SARS-CoV-2 positive group compared to the negative group after adjustment for age and BMI (52.8 nmol/l ± 11.0 versus 64.5 nmol/l ± 11.1; p = 0.009). Being elderly (> 60 years) [Odds ratio 6 (95% Confidence Interval, CI 2-18; p = 0.001) as well as having type 2 diabetes (T2D) [OR 6 (95% CI 3-14); p < 0.001)] and low HDL cholesterol (HDL-c) [OR 6 (95% CI 3-14); p < 0.001)] were significant risk factors for COVID-19 infection independent of age, sex and obesity. CONCLUSIONS: Among Arab Gulf residents screened for SARS-CoV-2, serum 25(OH) D levels were observed to be lower in those who tested positive than negative individuals, but it was the presence of old age, diabetes mellitus and low-HDL-c that were significantly associated with risk of COVID-19 infection. Large population-based randomized controlled trials should be conducted to assess the protective effects of vitamin D supplementation against COVID-19.

Severe vitamin D deficiency is not related to SARS-CoV-2 infection but may increase mortality risk in hospitalized adults: a retrospective case-control study in an Arab Gulf country.

PURPOSE: As the world continues to cautiously navigate its way through the coronavirus disease 2019 (COVID-19) pandemic, several breakthroughs in therapies and vaccines are currently being developed and scrutinized. Consequently, alternative therapies for severe acute respiratory coronavirus 2 (SARS-CoV-2) prevention, such as vitamin D supplementation, while hypothetically promising, require substantial evidence from countries affected by COVID-19. The present retrospective case-control study aims to identify differences in vitamin D status and clinical characteristics of hospitalized patients screened for SARS-CoV-2, and determine associations of vitamin D levels with increased COVID-19 risk and mortality. METHODS: A total of 222 [SARS-CoV-2 (+) N = 150 (97 males; 53 females); SARS-CoV-2 (-) N = 72 (38 males, 34 females)] out of 550 hospitalized adult patients screened for SARS-CoV-2 and admitted at King Saud University Medical City-King Khalid University Hospital (KSUMC-KKUH) in Riyadh, Saudi Arabia from May-July 2020 were included. Clinical, radiologic and serologic data, including 25(OH)D levels were analyzed. RESULTS: Vitamin D deficiency (25(OH)D < 50 nmol/l) was present in 75% of all patients. Serum 25(OH)D levels were significantly lower among SARS-CoV-2 (+) than SARS-CoV-2 (-) patients after adjusting for age, sex and body mass index (BMI) (35.8 ± 1.5 nmol/l vs. 42.5 ± 3.0 nmol/l; p = 0.037). Multivariate regression analysis revealed that significant predictors for SARS-CoV-2 include age > 60 years and pre-existing conditions (p < 0.05). Statistically significant predictors for mortality adjusted for covariates include male sex [Odds ratio, OR 3.3 (95% confidence interval, CI 1.2-9.2); p = 0.02], chronic kidney disease [OR 3.5 (95% CI 1.4-8.7); p = 0.008] and severe 25(OH)D deficiency (< 12.5 nmol/l), but at borderline significance [OR 4.9 (95% CI (0.9-25.8); p = 0.06]. CONCLUSION: In hospital settings, 25(OH)D deficiency is not associated with SARS-CoV-2 infection, but may increase risk for mortality in severely deficient cases. Clinical trials are warranted to determine whether vitamin D status correction provides protective effects against worse COVID-19 outcomes.

Prevalence, Predictors, and Awareness of Coffee Consumption and Its Trend among Saudi Female Students.

This study aimed to investigate the prevalence, trends, and predictors of coffee consumption among Saudi female students and its association with anthropometric and demographic variables. A survey-based study using a face-to-face interview was designed, and 930 (aged 21.5 ± 2.1 years) apparently healthy female students from different departments of King Saud University participated. The prevalence of coffee consumption was significantly higher (88.2%, p < 0.03) in the central Riyadh region. Coffee consumers had significantly higher prevalence of being overweight than non-consumers (p = 0.02). The frequency of coffee consumption was significantly higher (p < 0.02) in students who were single and belonged to families with a moderate income level. Coffee consumption was significantly higher among first-year students with a high-scale grade point average (GPA) (p < 0.001 and p = 0.03, respectively). Increased coffee consumption during exam and stress conditions was associated with unhealthy dietary habits such as using more sugar and spices. The prevalence of coffee consumption was high among Saudi females. High body mass index (BMI) and increased family income level were strong determinants for coffee consumption. Continued nutritional education and awareness about the potential positive and negative health effects of coffee consumption and the importance of food label use should be provided to younger generations in order to correct the wrong perceptions.

Vitamin D Correction Down-Regulates Serum Amyloid P Component Levels in Vitamin D Deficient Arab Adults: A Single-Arm Trial.

Vitamin D (VD) has been observed to have anti-inflammatory properties. However, the effects of VD supplementation on the serum amyloid P component (SAP) has not been established. This study aimed to investigate the effect of VD supplementation on serum SAP levels in Arab adults. A total of 155 VD-deficient adult Saudis (56 males and 99 females) were recruited in this non-randomized, 6-month, single-arm trial. The intervention was as follows; cholecalciferol 50,000 international units (IU) every week for the first 2 months, followed by 50,000 twice a month for the next two months, and for the last two months, 1000 IU daily. Serum 25(OH)D, SAP, C-reactive protein (CRP), lipid profile, and glucose were assessed at baseline and post-intervention. At post-intervention, VD levels were significantly increased, while SAP levels significantly decreased in all study participants. Remarkably, this reduction in SAP was more significant in males than females after stratification. SAP was inversely correlated with VD overall (r = -0.17, p < 0.05), and only in males (r = -0.27, p < 0.05) after stratification according to sex after 6 months of VD supplementation. Such a relationship was not observed at baseline. VD supplementation can favorably modulate serum SAP concentrations in Arab adults, particularly in males.

The Prevalence and Awareness Concerning Dietary Supplement Use among Saudi Adolescents.

Current dietary supplement (DS) use among Saudi school students is not well described. In this study, we aim to investigate the prevalence and predictors of DS use among adolescents. This cross-sectional study collected data via self-administered questionnaire from 1221 students (12 to 18 years). The overall prevalence of DS use was 26.2%, significantly higher in females than males (33% vs. 17.9%, p < 0.001). High proportion of female DS users demonstrated normal BMI than males (84% vs. 56.5%, p < 0.001). High percentage of male DS users were engaged in vigorous and/or high physical activity (PA) levels than female DS users (58.2% vs. 43%, p = 0.022; and 57.1% vs. 20.7%, p < 0.001, respectively). The main reasons for DS use among females were vitamin deficiency (63.3%), hair condition (37.6%) and nail health (23.5%) while in males, the main reasons were vitamin deficiency (58.4%) and body building (34.4%). The predictors of DS use in Saudi adolescents included being female, having high family income and being physically active. In conclusion, the overall prevalence and preference of DS use, though low among Saudi adolescents, was driven mostly by gender, physical activity levels and socioeconomic factors like family income. DS use guidelines and counselling among Saudi adolescents are warranted to improve public health.

Vitamin D Supplementation Is Associated with Increased Glutathione Peroxidase-1 Levels in Arab Adults with Prediabetes.

Vitamin D supplementation may be used to lower oxidative stress. This interventional study aimed to investigate the effects of vitamin D supplementation on glutathione peroxidase 1 (GPx1) levels and other parameters in Arab adults with prediabetes. A total of 203 Saudi adults with prediabetes and vitamin D deficiency [intervention group, N = 146 (53 males and 93 females); control group, N = 57 (25 males and 32 females)] were included in this non-randomized, six-month intervention study. The intervention group received 50,000 international units (IU) cholecalciferol tablets once a week for two months, then twice a month for the next two months, followed by 1000 IU daily for the last two months. The control group received no supplementation. Serum 25(OH)D, lipid profile, glucose, C-reactive protein (CRP) and GPx1 were measured at baseline and after six months. Post-intervention, GPx1 concentrations increased significantly in the intervention group [17.3 (11.5-59.0) vs 26.7 (11.4-59.9) p < 0.01] while no changes were observed in the control group (p = 0.15). This significant increase in 25(OH)D and GPx1 levels persisted after adjusting for age and BMI. Stratification according to sex revealed that this favourable increase in GPx1 was true only for males (p = 0.002). In all groups, baseline GPx1 was inversely correlated with low density lipoprotein (LDL)-cholesterol (r = -0.26, p < 0.01) and body mass index (BMI) (r = -0.20, p < 0.05), while positively correlated with age (r = 0.18, p < 0.05) and systolic blood pressure (r = 0.19, p < 0.05). In conclusion, vitamin D supplementation favourably enhanced GPx1 levels in adult Arabs with prediabetes, particularly in males.

Effects of different vitamin D supplementation strategies in reversing metabolic syndrome and its component risk factors in adolescents.

There is little evidence on the efficacy of various vitamin D supplementation strategies in reversing metabolic syndrome (MetS) in adolescents. The present study aims to fill this gap. A total of 535 (243/292) out of 650 apparently healthy Saudi adolescents were randomly selected from the Vitamin D School Project database which has baseline and post-intervention information of more than 1000 Saudi adolescents 12-18 years old attending 34 schools in Riyadh, Saudi Arabia from Nov 2014-May 2015. Allocation of intervention was done in 3 groups using cluster randomization: vitamin D tablet, 1000IU/day (N = 180; 69 boys, 111 girls); vitamin D fortified milk consumption, 200 ml/day, 40IU/100 ml (N = 189; 93 boys, 96 girls) and control (educational awareness) (N = 166; 81 boys, 85 girls). All groups were given educational awareness on how to increase vitamin D levels. All groups were matched for BMI and analysis adjusted for age. Post-intervention and using intent-to-treat approach, within-group analysis revealed a statistically significant increase in 25(OH)D levels in all groups, and a clinically significant increase in favor of the tablet group (between-group) [10.7 nmol/l (34.7%) versus 6.3 nmol/l (19.8%) in milk and 2.1 nmol/l (7.0%) in control; p < 0.001], adjusted for age and BMI-matched. Between group analysis also revealed a clinically significant decrease in triglycerides (p = 0.05), glucose (p < 0.001) and systolic blood pressure (p = 0.005) as well as a clinically significant increase in HDL-cholesterol (p = 0.004) over time, all in favor of the tablet group. Within-group comparison showed a significant decrease in the incidence of MetS in the tablet group (9.4% versus 4.4%; p < 0.05) only. In conclusion, oral vitamin D supplementation is superior to vitamin D fortified milk in improving vitamin D status. Reduction in the incidence of MetS in the Arab adolescent population secondary to vitamin D correction may be dose-dependent.

Efficacy of vitamin D supplementation according to vitamin D-binding protein polymorphisms.

OBJECTIVES: The aim of this study was to determine the influence of vitamin D-binding protein (DBP) gene polymorphisms in vitamin D metabolites before and after vitamin D supplementation. METHODS: In all, 234 participants (126 women; 108 men) with vitamin D deficiency [25(OH)D <50 nmol/L] were given 50 000 IU of vitamin D supplements for 8 wk followed by daily maintenance of 1000 IU for 4 mo. Two single-nucleotide polymorphisms (rs4588 and rs7041) in DBP coding gene were assessed. RESULTS: Baseline 25(OH)D was significantly in higher in participants with homozygous major genotype of rs7041 than other genotypes (P = 0.02). Postsupplementation 25(OH)D was significantly higher in participants with homozygous major genotypes of either rs4588 and rs7041 than other genotypes (P < 0.001). Participants with the minor allele of either rs4588 or rs7041 were 2.9 (1.9-4.5) times and 3.7 (2.1-6.6) times, respectively, more likely to be non-responders (postsupplementation 25 OHD <50 nmol/L) than those homozygous for the major allele at these locations (P < 0.001). Furthermore, participants with homozygous minor and heterozygous genotype of rs7041 were 6.2 and 4.2times more likely to be non-responders than those with the homozygous major genotype (P < 0.001) even after adjustments for age, sex, body mass index, baseline 25(OH)D concentration, and other alleles. Participants with homozygous minor and heterozygous genotypes of rs4588 were 4.1 and 12.4times more likely to be non-responders than those with homozygous major genotypes. These significant risks, however, were lost after adjustment. CONCLUSIONS: rs7041 and rs4588 variants of the DBP gene are associated with variations in 25(OH)D levels and efficacy of response to vitamin D supplementation in Saudi Arabian adults.

Vitamin D Supplementation Modestly Reduces Serum Iron Indices of Healthy Arab Adolescents.

Vitamin D deficiency has been shown to affect iron status via decreased calcitriol production, translating to decreased erythropoiesis. The present study aimed to determine for the first time whether vitamin D supplementation can affect iron levels among Arab adolescents. A total of 125 out of the initial 200 Saudi adolescents with vitamin D deficiency (serum 25(OH)D < 50 nmol/L) were selected from the Vitamin D-School Project of King Saud University in Riyadh, Saudi Arabia. Cluster randomization was done in schools, and students received either vitamin D tablets (1000 IU/day) (N = 53, mean age 14.1 ± 1.0 years) or vitamin D-fortified milk (40IU/200mL) (N = 72, mean age 14.8 ± 1.4 years). Both groups received nutritional counseling. Anthropometrics, glucose, lipids, iron indices, and 25(OH)D were measured at baseline and after six months. Within group analysis showed that post-intervention, serum 25(OH)D significantly increased by as much as 50%, and a parallel decrease of -42% (p-values <0.001 and 0.002, respectively) was observed in serum iron in the tablet group. These changes were not observed in the control group. Between-group analysis showed a clinically significant increase in serum 25(OH)D (p = 0.001) and decrease in iron (p < 0.001) in the tablet group. The present findings suggest a possible inhibitory role of vitamin D supplementation in the iron indices of healthy adolescents whose 25(OH)D levels are sub-optimal but not severely deficient, implying that the causal relationship between both micronutrients may be dependent on the severity of deficiency, type of iron disorder, and other vascular conditions that are known to affect hematologic indices. Well-designed, randomized trials are needed to confirm the present findings.

IGF and IGFBP as an index for discrimination between vitamin D supplementation responders and nonresponders in overweight Saudi subjects.

Vitamin D deficiency is common in the Kingdom of Saudi Arabia (KSA). Therefore, it is significant to recognize which biochemical markers modulate serum 25 hydroxyvitamin D (25(OH)D) in response to vitamin D supplementation in such a population. Our aim was to study the correlation of insulin-like growth factor (IGF) and insulin growth factor binding protein (IGFBP) with serum 25(OH)D in response to vitamin D supplementation in a Saudi population. A total of 199 (89 males/110 females) vitamin D deficient subjects (25(OH)D level <50 nmol/L), aged 40.4 ±â€Š11.4 years, were given vitamin D supplements (50,000 IU/mL every week) for the first 2 months, then twice a month for 2 months, followed by daily 1000 IU in the last 2 months. Fasting blood samples were taken at baseline and 6 months after the final dose of vitamin D. Serum 25(OH)D, IGF-1 and IGF-2, and IGFBPs 2-5 were measured. Vitamin D response was computed for all subjects as the difference in levels of serum 25(OH)D concentration at the end of 6 months compared to baseline. After intervention, serum 25(OH)D concentration significantly increased from 35.6 nmol/L (26.6-43.5) to 61.8 nmol/L (54.8-73.3) in responder subjects (P < .01) and from 35.1 nmol/L (21.2-58.2) to 38.3 nmol/L (25.5-48.3) in nonresponders (P = .13). Subjects with lower baseline serum IGF-II, IGFBP-2, and IGF-1/IGFBP-3 ratio are more sensitive to acute vitamin D status changes. IGF1 and IGF-1/IGFBP-3 ratio significantly increased in all subjects after 6 months (P = .01). Changes in 25(OH)D was significantly associated with changes in IGFBP-2 and IGF-1/IGFBP-3 ratio in responders only. This study proposes that changes in circulating IGF-I and IGFBP-3 are modulated by vitamin D supplementation and can be taken into consideration in investigations involving vitamin D correction. Moreover, increase in serum 25(OH)D and IGF-I/IGFBP-3 molar ratio are more sensitive markers for the response to vitamin D supplementation in Saudi population.

Efficacy of different modes of vitamin D supplementation strategies in Saudi adolescents.

Vitamin D deficiency is rampant in the Middle East, even in children and adolescents. This study was designed to investigate the effects of different vitamin D repletion strategies commonly used on serum vitamin D levels of Saudi adolescents. STUDY DESIGN: A 6-month multi-center, controlled, clinical study, involving 34 schools in the central region of Riyadh, Saudi Arabia. Different strategies of vitamin D supplementation were tested (200 ml fortified milk of different brands or vitamin D tablet (1,000IU). Anthropometrics were taken and fasting blood samples withdrawn at baseline and after intervention for the quantification of serum glucose, lipid profile and 25(OH) vitamin D. A significant increase in 25(OH)D level was observed in subjects supplemented with vitamin D tablet, milk brand 2 and milk brand 4, whereas subjects supplied with fortified milk brands 1 and 3 respectively, exhibited a significant decrease in 25(OH)D levels. Analysis of covariance showed that after adjusting for baseline 25(OH)D, age, gender and BMI, the mean 25(OH)D levels of children who were taking vitamin D tablet (9.1 ±â€¯0.8 nmol/l) and milk brand 4 were significantly higher (7.3 ±â€¯1.1 nmol/l) than children taking milk brand 2 (1.6 ±â€¯1.0 nmol/l). Subjects supplied with milk brands 1 and 2 exhibited a significant increase in total cholesterol level, while it dropped significantly in subjects taking milk brand 3, while no changes were observed in other groups. Different strategies in vitamin D supplementation used in this clinical study elicited varying degrees of improvement in serum 25(OH)D level. The observed outcomes were dependent on the strategy and gender in the Saudi adolescent population, with oral tablet supplementation being favored in boys.

Calcium and vitamin D in human health: Hype or real?

The incidence and prevalence of vitamin D deficiency are increasing worldwide. It is estimated that over 50% of the world's population have low vitamin D (i.e., hypovitaminosis D; serum levels below 30 ng/mL). In vitamin D inadequacy, human physiological systems work inefficiently. In humans, 80% of the vitamin D is synthesized in the presence of ultraviolet rays from sunlight; for the rest, we rely on diet and nowadays, supplements. The latter becomes important when one is exposed to less than optimal amounts of sunlight, inability to generate vitamin D in the skin efficiently, and/or having conditions that lead to decreased intestinal absorption or increased catabolism of vitamin D. The normal serum 25-hydroxyvitamin D [25(OH)D] level is around 30 ng/mL (75 nmol/L) and the optimal range is between 30 and 60 ng/mL (75-150 nmol/L). In 2011, the Institute of Medicine (IOM) suggested that 600IU of vitamin D is adequate for people below age 71 who are not exposed to sunshine. Although this might be relevant to the ambulatory healthy white Caucasians to achieve serum 25(OH)D level of 20 ng/mL, but it is insufficient for other ethnic groups. Moreover, the IOM recommendations are not suitable for those who live outside North America. Vitamin D requirements are higher during adolescence, pregnancy and lactation, and in many other disease conditions. Most clinicians consider 30 ng/mL as the minimum serum level of 25(OH)D necessary to maintain good health. In the absence of sunlight exposure and with daily oral intake of 600IU vitamin D, very few people would reach serum 25(OH)D level above 30 ng/mL. While an additional daily intake of 1000IU of vitamin D are required for people with lighter-skin color, those with darker complexion and the elderly, require a minimum of 2000IU/day to maintain serum 25(OH)D levels over 30 ng/mL; 5000 IU/day supplement is considered as the safe daily upper limit of supplementation. Vulnerable groups such as the disabled and/or house-bound, obese, with gastrointestinal abnormalities and/or malabsorption syndromes, institutionalized people (e.g., nursing homes, prisons, etc.), and pregnant and lactating women need approximately 4000IU per day for optimal physiological activity. Vitamin D is essential for gastrointestinal calcium absorption, mineralization of osteoid tissue and maintenance of serum ionized calcium level. It is also important for other physiological functions, such as muscle strength, neuromuscular coordination, hormone release, subduing autoimmunity, and curtailing the development of certain cancers.