Calcium-vitamin D-fortified milk is as effective on circulating bone biomarkers as fortified juice and supplement but has less acceptance: a randomised controlled school-based trial

Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline

BACKGROUND

Numerous studies demonstrate associations between serum concentrations of 25-hydroxyvitamin D (25[OH]D) and a variety of common disorders, including musculoskeletal, metabolic, cardiovascular, malignant, autoimmune, and infectious diseases. Although a causal link between serum 25(OH)D concentrations and many disorders has not been clearly established, these associations have led to widespread supplementation with vitamin D and increased laboratory testing for 25(OH)D in the general population. The benefit-risk ratio of this increase in vitamin D use is not clear, and the optimal vitamin D intake and the role of testing for 25(OH)D for disease prevention remain uncertain.

OBJECTIVE

To develop clinical guidelines for the use of vitamin D (cholecalciferol [vitamin D3] or ergocalciferol [vitamin D2]) to lower the risk of disease in individuals without established indications for vitamin D treatment or 25(OH)D testing.

METHODS

A multidisciplinary panel of clinical experts, along with experts in guideline methodology and systematic literature review, identified and prioritized 14 clinically relevant questions related to the use of vitamin D and 25(OH)D testing to lower the risk of disease. The panel prioritized randomized placebo-controlled trials in general populations (without an established indication for vitamin D treatment or 25[OH]D testing), evaluating the effects of empiric vitamin D administration throughout the lifespan, as well as in select conditions (pregnancy and prediabetes). The panel defined "empiric supplementation" as vitamin D intake that (a) exceeds the Dietary Reference Intakes (DRI) and (b) is implemented without testing for 25(OH)D. Systematic reviews queried electronic databases for publications related to these 14 clinical questions. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology was used to assess the certainty of evidence and guide recommendations. The approach incorporated perspectives from a patient representative and considered patient values, costs and resources required, acceptability and feasibility, and impact on health equity of the proposed recommendations. The process to develop this clinical guideline did not use a risk assessment framework and was not designed to replace current DRI for vitamin D.

RESULTS

The panel suggests empiric vitamin D supplementation for children and adolescents aged 1 to 18 years to prevent nutritional rickets and because of its potential to lower the risk of respiratory tract infections; for those aged 75 years and older because of its potential to lower the risk of mortality; for those who are pregnant because of its potential to lower the risk of preeclampsia, intra-uterine mortality, preterm birth, small-for-gestational-age birth, and neonatal mortality; and for those with high-risk prediabetes because of its potential to reduce progression to diabetes. Because the vitamin D doses in the included clinical trials varied considerably and many trial participants were allowed to continue their own vitamin D-containing supplements, the optimal doses for empiric vitamin D supplementation remain unclear for the populations considered. For nonpregnant people older than 50 years for whom vitamin D is indicated, the panel suggests supplementation via daily administration of vitamin D, rather than intermittent use of high doses. The panel suggests against empiric vitamin D supplementation above the current DRI to lower the risk of disease in healthy adults younger than 75 years. No clinical trial evidence was found to support routine screening for 25(OH)D in the general population, nor in those with obesity or dark complexion, and there was no clear evidence defining the optimal target level of 25(OH)D required for disease prevention in the populations considered; thus, the panel suggests against routine 25(OH)D testing in all populations considered. The panel judged that, in most situations, empiric vitamin D supplementation is inexpensive, feasible, acceptable to both healthy individuals and health care professionals, and has no negative effect on health equity.

CONCLUSION

The panel suggests empiric vitamin D for those aged 1 to 18 years and adults over 75 years of age, those who are pregnant, and those with high-risk prediabetes. Due to the scarcity of natural food sources rich in vitamin D, empiric supplementation can be achieved through a combination of fortified foods and supplements that contain vitamin D. Based on the absence of supportive clinical trial evidence, the panel suggests against routine 25(OH)D testing in the absence of established indications. These recommendations are not meant to replace the current DRIs for vitamin D, nor do they apply to people with established indications for vitamin D treatment or 25(OH)D testing. Further research is needed to determine optimal 25(OH)D levels for specific health benefits.

Vitamin D fortification of foods - sensory, acceptability, cost, and public acceptance considerations

In terms of vitamin D food fortification, there are a number of important considerations in relation to selection of the food vehicle and fortificant. While there has been much research focus on the ability of fortified foods to improve vitamin D status, other considerations, such as sensory properties and acceptability, cost, and public attitudes around vitamin D-fortified foods, have received less attention. Thus, the present narrative review aimed to summarize the existing knowledge around these important considerations. In summary, its findings suggest that: i) vitamin D addition to various food vehicles, at levels consistent with the supply of part or all the recommended intake, does not alter their sensory characteristics or overall acceptability; ii) overall, vitamin D fortification of foods is relatively cost-effective, despite the fact that some attitudinal studies highlighted participant concerns about the potential cost/expense of vitamin D-fortified foods; iii) evidence from various attitudinal studies suggest a high level of acceptance and/or purchase intention (i.e., extent to which customers are willing and inclined to buy) of vitamin D-fortified food products by the general public; and iv) there have been repeated calls for vitamin D public health educational/information campaigns to help educate consumers about the health risks associated with vitamin D deficiency and nutritional benefits associated with consumption of vitamin D-fortified foods. Such campaigns could positively mediate attitudes and acceptance of vitamin D-fortified foods amongst the public, and could also help address misconceptions and allay fears around vitamin D for concerned individuals. Lastly, the findings of the present review also highlight the existence of between-country differences, even within Europe, in relation to attitudes and purchase intention of vitamin D-fortified foods and the perceived appropriateness of certain food vehicles for vitamin D fortification, as well as the best mix of communication channels for a vitamin D public health educational/information campaign.

Strategic food vehicles for vitamin D fortification and effects on vitamin D status: A systematic review and meta-analysis of randomised controlled trials

There has been growing interest in the potential of vitamin D food fortification in Europe as a means of addressing low vitamin D status. The WHO-FAO suggest that choosing a suitable food vehicle and ensuring the combination of the food vehicle and the fortificant will be efficacious and effective are of key importance to a successful food fortification programme. Our key objective was to conduct a systematic review and meta-analysis to investigate the effect of various animal- and plant-based food vehicles fortified with vitamin D (as D3 or D2) on circulating 25-hydroxyvitamin D [25(OH)D] concentrations. A list of prioritised food vehicles was established and we searched PubMed, Embase, Scopus and Web of Science for randomised controlled trials (RCTs) which used these vehicles individually, and which met prespecified criteria. The searches identified 49 papers which described suitable RCTs using vitamin D-fortified bread/savoury biscuits (n = 5), orange juice (n = 5), UV-mushrooms (n = 8), cheese (n = 3), yogurt (n = 5), fluid milk (n = 13), powdered milk (n = 5), eggs (n = 2), edible oils (n = 4), or breakfast cereal (n = 1). No suitable RCTs were identified for rice, maize flour, butter, margarine or dairy spreads, plant-based milk or yogurt alternatives. Random-effects meta-analyses of each food vehicle individually indicated weighted mean differences (WMD) in 25(OH)D in the range ∼9-35 nmol/L (3-15 RCT arms, depending on vehicle), and all statistically significant (P < 0.01-0.0001), with the exception of UV-mushrooms (P = 0.06). Heterogeneity was variable (I2 =33-99%, depending on vehicle), but subgroup analysis based on vitamer and dose reduced it in some instances. Sub-group analysis on the basis of whether the food vehicles were from plant-based or animal-based origin showed no significant difference in WMD (15.2 versus 15.9 nmol/L, respectively; P = 0.48). These results support the use of various animal- and plant-based food vehicles for vitamin D fortification to improve circulating 25(OH)D concentrations in populations. This work was registered with PROSPERO as CRD42023439883.

The Effects of Dairy Product Supplementation on Bone Health Indices in Children Aged 3 to 18 Years: A Meta-Analysis of Randomized Controlled Trials

Childhood and adolescence are critical periods for optimizing skeletal growth. Dairy products are valuable sources of bone-beneficial nutrients, particularly calcium and protein. A random-effects meta-analysis of published randomized controlled trials was performed to quantitatively assess the effects of dairy supplementation on bone health indices in children and adolescents. The PubMed and Web of Science databases were searched. Dairy supplementation increased whole-body bone mineral content (BMC) (+25.37 g) and areal bone mineral density (aBMD) (+0.016 g/cm2), total hip BMC (+0.49 g) and aBMD (+0.013 g/cm2), femoral neck BMC (+0.06 g) and aBMD (+0.030 g/cm2), lumbar spine BMC (+0.85 g) and aBMD (+0.019 g/cm2), and height (0.21 cm). When expressed as a percentage difference, whole-body BMC was increased by 3.0%, total hip BMC by 3.3%, femoral neck BMC by 4.0%, lumbar spine BMC by 4.1%, whole-body aBMD by 1.8%, total hip aBMD by 1.2%, femoral neck aBMD by 1.5%, and lumbar spine aBMD by 2.6%. Dairy supplementation increased serum insulin-like growth factor I concentrations (19.89 nmol/L) and reduced concentrations of urinary deoxypyridinoline (-1.78 nmol/mmol creatinine) and serum parathyroid hormone (-10.46 pg/mL) but did not significantly affect the serum concentrations of osteocalcin, bone alkaline phosphatase, and C-terminal telopeptide of type 1 collagen. Serum 25-hydroxyvitamin D concentrations (+4.98 ng/mL) increased with vitamin D-fortified dairy supplementation. The positive effects on bone mineral mass parameters and height were generally consistent across subgroups defined by sex, geographical region, baseline calcium intake, calcium from the supplementation, trial duration, and Tanner stages. In summary, dairy supplementation during growth leads to a small but significant increase in bone mineral mass parameters, and these findings are generally supported by the changes in several biochemical parameters related to bone health.

Fortification of Staple Foods for Household Use with Vitamin D: An Overview of Systematic Reviews

Vitamin D deficiency is a global public health concern with significant implications for bone health and chronic disease prevention. Our aim was to summarize the evidence from Cochrane and other systematic reviews evaluating the benefits or harms of vitamin D fortification of staple foods for household use. In April 2023, we systematically searched Ovid MEDLINE, Embase, Epistemonikos and the Cochrane Database of Systematic Reviews for systematic reviews investigating the effects of vitamin D fortification of food in general populations of any age. We used Cochrane methodology and assessed the methodological quality of included studies using AMSTAR (A MeaSurement Tool to Assess Systematic Reviews). We assessed the degree of overlap among reviews. All outcomes included in systematic reviews were assessed. The protocol is registered in PROSPERO (registration number: CRD42023420991). We included 27 systematic reviews out of 5028 records for analysis. Overall, 11 out of 12 systematic reviews calculating pooled estimates reported a significant increase in serum 25(OH)D concentrations. The mean change in serum 25(OH)D concentrations per additional 100 units of vitamin D ranged from 0.7 to 10.8 nmol/L. Fortification of food with vitamin D showed a reduction in the prevalence of vitamin D deficiency based on high-certainty evidence. Parathormone (PTH) levels were described to decrease, bone mineral density to increase, while the effects on other bone turnover markers were inconsistent. Fortification did not significantly impact most anthropometric parameters, but it seemed to positively influence lipid profiles. In summary, fortification of food with vitamin D results in a reduction of vitamin D deficiency and might increase serum 25(OH)D concentrations, to varying extents depending on the fortified vehicle and population characteristics. Additionally, fortification may have a positive impact on bone turnover and lipid metabolism but may only have a limited effect on anthropometric parameters.

Administration of whey protein complexed vitamin D3 to vitamin D3-deficient growing Sprague-Dawley rats

Vitamin D deficiency is a global health issue with consequences for bone health. Complexation of vitamin D₃ with specific whey proteins might increase the bioavailability and enhance the effect of dietary supplementation on health outcomes. The current rat study was set up to investigate if complexation of vitamin D₃ with whey protein isolate (WPI) or β-lactoglobulin (B-LG) increases bioavailability of the vitamin and how it impacts markers of bone turnover and bone structure. For 8 weeks, growing male Sprague Dawley rats (n = 48) were fed a vitamin D-deficient diet and during the final 4 weeks gavage dosing of vitamin D₃ either alone (VitD) or complexed with WPI (VitD + WPI) or β-LG (VitD + B-LG) was administered. A placebo treatment (placebo) was also included. After sacrifice, samples of bone were collected and analyzed using biomechanical testing and μCT scanning. The concentrations of vitamin D₃, vitamin D₃ metabolites and bone markers (P1NP and CTX) were measured in serum. The results showed that VitD + B-LG appeared to induce lower levels of 25-hydroxy vitamin D₃ in serum compared to VitD alone. Markers of bone turnover were generally higher in the VitD group compared to placebo and the VitD + WPI and VitD + B-LG treatments. No effects of treatments on bone strength or bone microstructure were detected. In conclusion, whey protein complexation of vitamin D₃ supplements appeared to have no beneficial effects on circulating vitamin D₃ metabolites but this did not impose changes in bone strength or trabecular bone microstructure.

How Much Does Serum 25(OH)D Improve by Vitamin D Supplement and Fortified Food in Children? A Systematic Review and Meta-Analysis

OBJECTIVES

This study was conducted to respond certain important questions regarding the efficacy of vitamin D fortification and supplementation in children using a meta-analytical approach.

METHODS

MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar were searched, and 2341 studies were found in a preliminary search. After screening of titles and abstracts, 31 studies were selected.

RESULTS

Significant raises in circulating 25-hydroxy vitamin D (25(OH)D) concentrations were observed in both groups that took vitamin D supplement (mean difference [MD] 28.7, 95% confidence interval [CI] 22.5-34.9) and vitamin D-fortified foods (MD 20.29, 95% CI 13.3-27.2). The meta-regression revealed a significant association between age of participants (B -1.4, 95% CI -2.8, -0.02, P = 0.047) and dose of vitamin D (B 0.007, 95% CI 0.003, 0.01, P < 0.001), with the effect on serum 25(OH)D concentrations. The analysis showed that serum 25(OH)D concentration increases by 0.7 nmol/L for every 100 IU of vitamin D intake after adjustment for age, baseline serum 25(OH)D and latitude which is far less than the reported amount in adults.

CONCLUSIONS

Altogether, these findings indicate that in a mass vitamin D fortification program, circulating 25(OH)D concentration response in children may be lower in children than in adults and vitamin D supplementation may still be needed in this subpopulation.

Formulation Strategies for Improving the Stability and Bioavailability of Vitamin D-Fortified Beverages: A Review

Vitamin D is a lipophilic bioactive that plays an important role in bone health. Fortification of beverages, such as milk, fruit juices, teas, and vegetable drinks, could be an efficient strategy to prevent vitamin D deficiency and its associated effects on health. This review summarizes the current understanding of beverage fortification strategies with vitamin D and the resulting effects on the stability, bioaccessibility, and sensory properties of the formulated products. The direct addition technique has been the conventional approach to fortifying beverages. In addition, encapsulation has been pointed out as a desirable delivery approach to increase stability, preserve bioactivity, and enhance the absorption of vitamin D in beverage systems. The literature reports the potential applicability of several methods for encapsulating vitamin D in beverages, including spray drying, micro/nanoemulsions, nanostructured lipid carriers, liposomes, and complexation to polymers. Some of these delivery systems have been assessed regarding vitamin D stability, but there is a lack of kinetic data that allow for the prediction of its stability under industrial processing conditions. Moreover, in some cases, the applicability of some of these delivery systems to real beverages as well as the in vivo efficacy were not evaluated; thus, fortification strategies with a global outreach are lacking.

Vitamin D biomarkers for Dietary Reference Intake development in children: a systematic review and meta-analysis

BACKGROUND

Circulating 25-hydroxyvitamin D [25(OH)D] has been the accepted vitamin D exposure/intake biomarker of choice within recent DRI exercises, but use of other vitamin D-related biomarkers as well as functional markers has been suggested. These may be of value in future vitamin D DRI exercises, such as the FAO/WHO's one for young children.

OBJECTIVES

To systematically review the usefulness of circulating 25(OH)D, parathyroid hormone (PTH), free and bioavailable 25(OH)D, C3-epimer of 25(OH)D, vitamin D3, 24,25-dihydroxyvitamin D [24,25(OH)2D], and bone turnover markers and calcium absorption as vitamin D biomarkers for DRI development in children.

METHODS

Methods included structured searches of published articles, full-text reviews, data extraction, quality assessment, meta-analysis, and random-effects meta-regression.

RESULTS

Fifty-nine vitamin D supplementation randomized controlled trials (RCTs) were included (39 in infants/children as the priority group and the remainder in adults since pediatric studies were absent/limited). Vitamin D supplementation significantly raised circulating 25(OH)D in infants and children, but the response was highly heterogeneous [weighted mean difference (WMD): 27.7 nmol/L; 95% CI: 22.9, 32.5; 27 RCTs; I2 = 93%]. Meta-regression suggested an increase by 1.7 nmol/L (95% CI: 0.7, 2.6) in serum 25(OH)D per each 100-IU increment in vitamin D intake (P = 0.0005). Vitamin D supplementation had a significant effect on circulating 24,25(OH)2D (WMD: 3.4 nmol/L; 95% CI: 2.4, 4.5; 13 RCTs; I2 = 95%), with a dose-response relation (+0.15 nmol/L per 100 IU; 95% CI: -0.01, 0.29). With circulating PTH, although there was a significant effect of vitamin D on WMD (P = 0.05), there was no significant dose-response relation (P = 0.32). Pediatric data were too limited in relation to the usefulness of the other biomarkers.

CONCLUSIONS

Circulating 25(OH)D may be a useful biomarker of vitamin D exposure/intake for DRI development in infants and children. Circulating 24,25(OH)2D also showed some promise, but further data are needed, especially in infants and children.

Vitamin D Incorporation in Foods: Formulation Strategies, Stability, and Bioaccessibility as Affected by the Food Matrix

Inadequate intake of vitamin D is a global health issue related to severe diseases, mainly involving subjects with dark skin pigmentation, patients affected by malnutrition, malabsorption syndromes, or obesity, and elderly people. Some foods fortified with vitamin D have been tested in vivo, but fortification strategies with a global outreach are still lacking. This review is focused on food fortification with vitamin D, with the aim to collect information on (a) formulation strategies; (b) stability during processing and storage; and (c) in vitro bioaccessibility. Approaches to add vitamin D to various foods were analyzed, including the use of free vitamin D, vitamin D loaded in simple and double nanoemulsions, liposomes, casein micelles, and protein nanocapsules. Numerous studies were reviewed to elucidate the impact of food technologies on vitamin D’s stability, and mechanisms that lead to degradation were identified—namely, acid-catalyzed isomerization, radical-induced oxidation, and photo-oxidation. There is, however, a lack of kinetic data that allow for the prediction of vitamin D’s stability under industrial processing conditions. The roles that lipids, proteins, fibers, and antioxidants play in vitamin bioaccessibility have been clarified in various studies, while future needs include the design of specific food matrices that simultaneously achieve a balance between the long-term stability, bioaccessibility and, ultimately, in vivo functionality of vitamin D.

School-based nutrition interventions can improve bone health in children and adolescents

Objectives

Osteoporosis is a major global health problem, and optimizing bone health during childhood and adolescence with adequate calcium and vitamin D intake is a recommendation to prevent the disease. School milk programs may be a viable approach to help children and adolescents increase calcium and vitamin D intakes while improving their bone health.

Methods

A review of the literature was conducted on school milk programs, including examination of details regarding these studies and their participants, and assessments of their effects on bone health in children and adolescents.

Results

Nearly all studies reviewed showed significant increases in the bone health behaviors and outcomes that were measured, such as bone mineral density, milk consumption, and calcium and vitamin D intake.

Conclusions

School milk programs can be effective in improving bone health in children and adolescents, and public health policies should be considered to help support and fund effective programs that promote bone health and prevent osteoporosis in population health.

The impact of vitamin D food fortification and health outcomes in children: a systematic review and meta-regression

OBJECTIVE

Vitamin D (vitD) deficiency is a global childhood health problem. Food fortification is a promising strategy to curb vitD deficiency. We aimed to assess the effectiveness of utilizing vitD fortification in staple foods to improve 25hydroxyvitamin D (25(OH)D) concentration and to reduce the prevalence of vitD deficiency among healthy children.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the use of vitD fortified food products compared to no fortification among healthy children aged 1-18 years old. We searched Medline, Embase, Global Health, and Cochrane (CENTRAL) databases from database inception until May 2019. Independently, six reviewers in pairs screened titles and abstracts, assessed the full text for eligibility, and performed data extraction and quality assessment. The primary outcome is the impact of fortification on 25(OH)D concentration. The secondary outcomes included the impact of fortification on the prevalence of vitD deficiency, school performance, cognitive function, school absences, infection rate, hospital admission length, and compliance with fortified food product consumption.

RESULTS

We identified 2229 articles. After assessing eligibility, 20 RCTs met the inclusion criteria. The eligible RCTs assessed the fortification of milk, cereal, juice, bread, yogurt, and cheese compared with no fortification. All RCTs, except for three, had a low risk of bias. Food fortification improved 25(OH)D concentration by a mean difference (MD) of 15.51 nmol/L (95% confidence interval (CI) 6.28, 24.74; I² = 99%), which resulted in a mean increase of 3 nmol/l for every 100 IU of vitD, when adjusted for baseline 25(OH)D concentration and country latitude. Additionally, the prevalence of vitD deficiency decreased by a risk ratio of 0.53 (95% CI 0.41, 0.69; I² = 95%), and cognitive function improved by a MD of 1.22 intelligence quotient (IQ) points (95% CI 0.65, 1.79; I² = 0%). The overall evidence quality was high.

CONCLUSION

VitD food fortification is an effective way to improve 25(OH)D concentration, prevent vitD deficiency, and improve IQ levels.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017057631.

DEFINITION OF VITAMIN D DEFICIENCY IN SCHOOLCHILDREN: SYSTEMATIC REVIEW WITH META-ANALYSIS

BACKGROUND

Vitamin D deficiency is being recognized as a pandemic due to the volume of people affected by the deficiency and the number of illnesses generated or stimulated by the deficiency. There is a lack of consensus in the literature on what is considered vitamin D deficiency [25(OH)D].

OBJECTIVE

This review brings together the most common levels of 25(OH)D found in healthy schoolchildren and what is considered deficient.

METHODS

This systematic review was based on the literature accessed from the electronic databases: MEDLINE, EMBASE, LILACS, SCOPUS and WEB OF SCIENCE. The following descriptors were used in English, Portuguese and Spanish: "Vitamin D"; "Vitamin D deficiency"; "Nutritional Supplements" as well as all their synonyms. The meta-analysis was performed considering the random model. Inclusion criteria: healthy children aged 6 to 12 years, studies that had vitamin D levels, defined vitamin D deficiency.

RESULTS

Of the 191 potentially eligible articles, only six articles were included, with 2618 students in total. The mean value of 25(OH)D was estimated at 18.11 ng/mL with 95% confidence interval. Among the articles found, three were considered deficiency levels below 20 ng/mL, one considered below 18 ng/mL, another below 15 ng/mL, and the latter below 11 ng/ mL. The prevalence of vitamin D deficiency among the articles was 48.6%, 7%, 98%, 64.63%, 19.5%, 28.4%, according to each classification used by the same.

CONCLUSION

The most common definition in the literature of 25(OH)D deficiency in schoolchildren was at levels below 20 ng/mL. No side effects have been reported in studies that used fortification and/or vitamin D supplementation. Daily supplementation is more effective than seasonal supplementation. However, more studies are needed to define what can be considered as optimal levels of 25(OH)D in children.

Vitamin D-fortified cooking oil is an effective way to improve vitamin D status: an institutional efficacy trial

PURPOSE

High prevalence of vitamin D deficiency (VDD) justifies a cost-effective and sustainable strategy to combat VDD in the community. This study was undertaken for the first time to evaluate the efficacy of daily consumption of vitamin D fortified sunflower oil with a meal.

METHODS

This single-blind trial was conducted in two separate institutions: one as intervention (D-fortified sunflower oil) group (DO, n₁ = 39) and the other as control (unfortified sunflower oil) group (SO, n₂ = 33). Participants consumed their lunches cooked either with D-fortified or unfortified cooking sunflower oil (500 IU/30 g) for 12 weeks. Dietary, anthropometric and biochemical assessments were done for all participants before and after the intervention.

RESULTS

A total of 65 subjects from both sexes aged 32.5 ± 4 years completed the intervention period. Serum 25(OH)D showed a significant increase in DO and a decrease in SO group (8.8 ± 9.3 vs. - 7.4 ± 6.4 ng/mL, p < 0.001). The rise in serum 25(OH)D in DO group was accompanied by a significant decrease in iPTH (DO: - 10.2 ± 29.4 vs. SO: + 9.2 ± 29.5 pg/mL; p = 0.009). A significant reduction in weight (p = 0.004), BMI (p = 0.029), waist girth (p < 0.001), serum total cholesterol (p = 0.0290) and LDL-C (p = 0.010) was observed in DO, as compared with SO group.

CONCLUSIONS

Cooking oil can be considered as an efficacious vehicle for mass fortification program to combat VDD. The improvement of vitamin D status may bring about betterment of certain cardiometabolic risk factors.

REGISTRATION NUMBER

Clinicaltrials.gov: NCT03826654.

Health effects of micronutrient fortified dairy products and cereal food for children and adolescents: A systematic review

INTRODUCTION

Micronutrient (MN) deficiencies cause a considerable burden of disease for children in many countries. Dairy products or cereals are an important food component during adolescence. Fortification of dairy products or cereals with MN may be an effective strategy to overcome MN deficiencies, but their specific impact on health in this age group is poorly documented.

METHODS

We performed a systematic review and meta-analysis (registration number CRD42016039554) to assess the impact of MN fortified dairy products and cereal food on the health of children and adolescents (aged 5-15 years) compared with non-fortified food. We reviewed randomised controlled trials (RCT) using electronic databases (MEDLINE, EMBASE, Cochrane library; latest search: January 2018), reference list screening and citation searches. Three pairs of reviewers assessed 2048 studies for eligibility and extracted data. We assessed the risk of bias and applied GRADE to rate quality of evidence.

RESULTS

We included 24 RCT (often multi MN fortification) with 30 pair-wise comparisons mainly from low- and middle income countries. A very small and non-significant increase of haemoglobin values emerged (0.09 g/dl [95%-CI: -0.01 to 0.18]; 13 RCT with iron fortification; very low quality of evidence). No significant difference was found on anaemia risk (risk ratio 0.87 [95%-CI: 0.76 to 1.01]; 12 RCT; very low quality), but a significant difference in iron deficiency anaemia favouring fortified food was found (risk ratio 0.38 [95%-CI: 0.18 to 0.81]; 5 RCT; very low quality). Similar effects were seen for fortified dairy products and cereals and different fortification strategies (mono- vs. dual- vs. multi-MN). Follow-up periods were often short and the impact on anthropometric measures was weak (low quality of evidence) Very low quality of evidence emerged for the improvement of cognitive performance, functional measures and morbidity.

CONCLUSIONS

Fortification of dairy products and cereal food had only marginal health effects in our sample population from 5-15 years. Further evidence is needed to better understand the health impact of fortified dairy products and cereals in this age group.

SYSTEMATIC REVIEW REGISTRATION

The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 26 May 2016 (registration number CRD42016039554).

Effect of Vitamin D Supplementation on Bone Turnover Markers in Children and Adolescents from North India

OBJECTIVES

Vitamin D is known to play an important role in bone mineral metabolism. Its deficiency may affect growth and status of bone markers in children. Hence, we undertook to study the status of bone markers in children with vitamin D deficiency (VDD) and impact of vitamin D3 supplementation on them.

MATERIALS AND METHODS

Total 468 out of 615 children and adolescents with VDD, who were given either of the three doses (600, 1000, and 2000) of vitamin D supplementation, were included in the study. These 468 children with pre- and postsupplementation preserved samples with available anthropometry, serum biochemistry, 25-hydroxy-vitamin D, and parathormone were evaluated for bone formation (procollagen type 1 amino-terminal propeptide [P1NP]) and resorption (β-cross laps [CTx]) markers.

RESULTS

The mean age and body mass index of these children were 11.3 ± 2.3 years (boys: 11.5 ± 2.4; girls: 12.2 ± 1.2 years; P = 0.03) and 18.1 ± 3.8 kg/m² (boys: 18.2 ± 3.9; girls: 17.6 ± 3.2 kg/m²; P = 0.208), respectively. There were 8.8% subjects with severe, 42.7% with moderate, and 48.5% with mild VDD. There was a significant decline in serum P1NP (from 691 ± 233 ng/ml to 640 ± 259 ng/ml, P < 0.001) and CTx (from 1.67 ± 0.53 ng/ml to 1.39 ± 0.51 ng/ml, P < 0.001) following supplementation. Though decline in serum P1NP and CTx levels was observed in both boys and girls, among all three supplementation groups and VDD categories, the effect was more marked in serum CTx than P1NP levels.

CONCLUSIONS

Vitamin D supplementation in VDD children resulted in decrease in both bone formation (P1NP) and resorption (CTx). The impact, however, was more marked on bone resorption than bone formation.

Effect of Vitamin D Supplementation, Food Fortification, or Bolus Injection on Vitamin D Status in Children Aged 2-18 Years: A Meta-Analysis

Meta-analyses on the effect of vitamin D intake on status in children are lacking, especially those focused on vitamin D-fortified foods. The objective of this meta-analysis was to investigate the effect of vitamin D interventions (fortified foods, supplements, bolus injections) on vitamin D status in children 2-18 y of age. Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, literature searches were conducted up to December 2016. Randomized placebo-controlled vitamin D interventions in healthy children aged 2-18 y were included. A random-effects model was used with I2 assessing heterogeneity. We included 26 trials (5403 children) with interventions (n = 9 fortified foods, n = 15 supplements, n = 2 bolus injections) from 100-4000 IU vitamin D/d over 4 wk to 2 y. The serum 25-hydroxyvitamin D [25(OH)D] weighted mean difference for all 26 trials (23.5 nmol/L; 95% CI: 20.7, 26.3 nmol/L; I2 = 99.9%) resulted in a mean increase of 1.0 nmol/L (95% CI: 0.3, 1.7 nmol/L) for each increase of 100 IU vitamin D/d (per 1 µg/d : 0.4 nmol/L; 95% CI: 0.1, 0.7 nmol/L). The response per 100 IU vitamin D/d was greater in trials with a mean baseline serum 25(OH)D <30 nmol/L, with the use of fortified foods and with baseline vitamin D intakes <100 IU/d. In conclusion, the serum 25(OH)D response to vitamin D intake differs on the basis of baseline status, intakes, and delivery mode, but not age, sex, or latitude.

Vitamin D in the Middle East and North Africa

PURPOSE

The Middle East and North Africa (MENA) region registers some of the lowest serum 25‑hydroxyvitamin D [25(OH)D] concentrations, worldwide. We describe the prevalence and the risk factors for hypovitaminosis D, completed and ongoing clinical trials, and available guidelines for vitamin D supplementation in this region.

METHODS

This review is an update of previous reviews published by our group in 2013 for observational studies, and in 2015 for randomized controlled trials (RCTs) from the region. We conducted a comprehensive search in Medline, PubMed, and Embase, and the Cochrane Library, using MeSH terms and keywords relevant to vitamin D, vitamin D deficiency, and the MENA region, for the period 2012-2017 for observational studies, and 2015-2017 for RCTs. We included large cross-sectional studies with at least 100 subjects/study, and RCTs with at least 50 participants per arm.

RESULTS

We identified 41 observational studies. The prevalence of hypovitaminosis D, defined as a 25‑hydroxyvitamin D [25(OH)D] level below the desirable level of 20 ng/ml, ranged between 12-96% in children and adolescents, and 54-90% in pregnant women. In adults, it ranged between 44 and 96%, and the mean 25(OH)D varied between 11 and 20 ng/ml. In general, significant predictors of low 25(OH)D levels were female gender, increasing age and body mass index, veiling, winter season, use of sun screens, lower socioeconomic status, and higher latitude.We retrieved 14 RCTs comparing supplementation to control or placebo, published during the period 2015-2017: 2 in children, 8 in adults, and 4 in pregnant women. In children and adolescents, a vitamin D dose of 1000-2000 IU/d was needed to maintain serum 25(OH)D level at target. In adults and pregnant women, the increment in 25(OH)D level was inversely proportional to the dose, ranging between 0.9 and 3 ng/ml per 100 IU/d for doses ≤2000 IU/d, and between 0.1 and 0.6 ng/ml per 100 IU/d for doses ≥3000 IU/d. While the effect of vitamin D supplementation on glycemic indices is still controversial in adults, vitamin D supplementation may be protective against gestational diabetes mellitus in pregnant women. In the only identified study in the elderly, there was no significant difference between 600 IU/day and 3750 IU/day doses on bone mineral density. We did not identify any fracture studies.The available vitamin D guidelines in the region are based on expert opinion, with recommended doses between 400 and 2000 IU/d, depending on the age category, and country.

CONCLUSION

Hypovitaminosis D is prevalent in the MENA region, and doses of 1000-2000 IU/d may be necessary to reach a desirable 25(OH)D level of 20 ng/ml. Studies assessing the effect of such doses of vitamin D on major outcomes, and confirming their long term safety, are needed.

Healthy changes in some cardiometabolic risk factors accompany the higher summertime serum 25-hydroxyvitamin D concentrations in Iranian children: National Food and Nutrition Surveillance

OBJECTIVE

To investigate seasonal variations of vitamin D status at different latitudes and if these changes are accompanied by corresponding variations in certain health parameters in children living in a broad latitudinal range in Iran.

DESIGN

Longitudinal study.

SUBJECTS

In total, 530 apparently healthy children aged 5-18 years were randomly selected from six regions of Iran with a latitudinal gradient from 29°N to 37·5°N. All anthropometric and biochemical assessments were performed twice during a year (summer, winter). High BMI (Z-score >1), low HDL cholesterol (150 mg/dl) were considered cardiometabolic risk factors.

RESULTS

Serum 25-hydroxyvitamin D (25(OH)D) showed between-season variation, with significantly higher concentrations (mean (sd)) in summer v. winter (43 (29) v. 27 (18) nmol/l; P33°N v. <33°N: 4·5; 0·09, 9·0; P=0·04) were predictors of change of serum 25(OH)D between two seasons.

CONCLUSIONS

Summertime improvement of vitamin D status was accompanied by certain improved cardiometabolic risk factors, notably serum TAG, total cholesterol and BMI, in children.

Dairy products and bone health: how strong is the scientific evidence?

The relevance of dairy produce for the diminishment of osteoporotic risk is still a matter of scientific debate due to the outcome of a few single observational studies. This review will address the most robust point estimate on the role of dairy products, as reported in systematic reviews and meta-analyses on randomised controlled trials in the case of bone mineralisation or prospective studies in the case of fracture risk. Plain dairy products or those fortified with Ca and/or vitamin D improve total body bone mineral content (BMC) by 45-50 g over 1 year when the daily baseline Ca intake is lower than 750 mg in Caucasians and Chinese girls. In Caucasian and Chinese women, Ca from (fortified) dairy products increases bone mineral density (BMD) by 0·7-1·8 % over 2 years dependent on the site of measurement. Despite the results on BMC, there are currently no studies that have investigated the potential of dairy products to reduce fracture risk in children. In adult Caucasian women, daily intake of 200-250 ml of milk is associated with a reduction in fracture risk of 5 % or higher. In conclusion, the role of dairy products for BMC or BMD has been sufficiently established in Chinese and Caucasian girls and women. In Caucasian women, drinking milk also reduces fracture risk. More research on the role of dairy products within the context of bone health-promoting diets is needed in specific ethnicities, other than Chinese and Caucasians, and in men.

Vitamin D replacement in children, adolescents and pregnant women in the Middle East and North Africa: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Hypovitaminosis D affects one-third to two-thirds of children and pregnant women from the Middle East and North Africa (MENA) region.

OBJECTIVE

To evaluate in infants, children, adolescents and pregnant women, from the MENA region, the effect of supplementation with different vitamin D doses on the change in 25-hydroxyvitamin D [25(OH)D] level reached, and other skeletal and non-skeletal outcomes.

METHODS

This is a systematic review of randomized controlled trials of vitamin D supplementation conducted in the MENA region. We conducted a comprehensive literature search in 7 databases, without language or time restriction, until November 2016. Two reviewers abstracted data from the included studies, independently and in duplicate. We calculated the mean difference (MD) and 95% CI of 25(OH)D level reached when at least 2 studies were eligible in each comparison (low (<800IU), intermediate (800-2000IU) or high (>2000IU) daily dose of vitamin D, or placebo). We pooled data using RevMan version 5.3.

RESULTS

We identified a total of 15 eligible trials: one in infants, 4 in children and adolescents and 10 in pregnant women. In children and adolescents, an intermediate vitamin D dose (1901IU/d), resulted in a mean difference in 25(OH)D level of 13.5 (95% confidence interval (CI) 8.1-18.8) ng/ml, compared to placebo, favoring the intermediate dose (p<0.001). The proportion of children and adolescents reaching a 25(OH)D level≥ 20ng/ml was 74% in the intermediate dose group. In pregnant women, four trials started supplementation at 12-16weeks of gestation and continued until delivery, and six trials started supplementation at 20-28weeks' gestation and stopped it at delivery. The MD in 25(OH)D level reached was 8.6 (95% CI 5.3-11.9) ng/ml (p<0.001) comparing the high dose (3662IU/d) to the intermediate dose (1836IU/d), and 12.3 (95% CI 6.4-18.2) ng/ml (p<0.001), comparing the high dose (3399IU/d) to the low dose (375IU/d). Comparing the intermediate (1832IU/d) to the low dose (301IU/d), the MD in 25(OH)D level achieved was 7.8 (95% CI 4.5-10.8) ng/ml (p<0.001). The proportion of pregnant women reaching a 25(OH)D level≥20ng/ml was 80%-90%, 73% and 27%-43% in the high, intermediate, and low dose groups, respectively. The risk of bias in the included studies, for children, adolescents and pregnant women, ranged from low to high across all doamins.

CONCLUSION

In children, adolescents and pregnant women from the MENA, an intermediate vitamin D dose of 1000-2000IU daily may be necessary to allow for the majority of the population to reach a desirable 25(OH)D level of 20ng/ml. Further high quality RCTs are required to confirm/refute the beneficial impact of vitamin D supplementation on various clinically important outcomes.

Effects of vitamin D-fortified low fat yogurt on glycemic status, anthropometric indexes, inflammation, and bone turnover in diabetic postmenopausal women: A randomised controlled clinical trial

BACKGROUND & AIMS

Low levels of serum 25-hydroxy vitamin D (25(OH)D) are common in type 2 diabetic patients and cause several complications particularly, in postmenopausal women due to their senile and physiological conditions. This study aimed to assess the effects of vitamin D-fortified low fat yogurt on glycemic status, anthropometric indexes, inflammation, and bone turnover in diabetic postmenopausal women.

METHODS

In a randomized, placebo-controlled, double-blind parallel-group clinical trial, 59 postmenopausal women with type 2 diabetes received fortified yogurt (FY; 2000 IU vitamin D in 100 g/day) or plain yogurt (PY) for 12 weeks. Glycemic markers, anthropometric indexes, inflammatory, and bone turnover markers were assessed at baseline and after 12 weeks.

RESULTS

After intervention, in FY group (vs PY group), were observed: significant increase in serum 25(OH)D and decrease of PTH (stable values in PY); significant improvement in serum fasting insulin, HOMA-IR, HOMA-B, QUICKI, and no changes in serum fasting glucose and HbA1c (significant worsening of all indexes in PY); significant improvement in WC, WHR, FM, and no change in weight and BMI (stable values in PY); significant increase of omentin (stable in PY) and decrease of sNTX (significant increase in PY). Final values of glycemic markers (except HbA1c), omentin, and bone turnover markers significantly improved in FY group compared to PY group. Regarding final values of serum 25(OH)D in FY group, subjects were classified in insufficient and sufficient categories. Glycemic status improved more significantly in the insufficient rather than sufficient category; whereas the other parameters had more amelioration in the sufficient category.

CONCLUSIONS

Daily consumption of 2000 IU vitamin D-fortified yogurt for 12 weeks improved glycemic markers (except HbA1c), anthropometric indexes, inflammation, and bone turnover markers in postmenopausal women with type 2 diabetes.

TRIAL REGISTRATION

www.irct.ir (IRCT2013110515294N1).