Low vitamin D levels are associated with both iron deficiency and anemia in children and adolescents

Improvement of vitamin D status through consumption of either fortified food products or supplement pills increased hemoglobin concentration in adult subjects: Analysis of pooled data from two randomized clinical trials

Background: It is documented that vitamin D may have a role in erythropoiesis as its deficiency is accompanied by an increased risk of anemia. Aim: This study aimed to examine whether improvement of vitamin D status through daily consumption of either fortified foods or supplements could impinge on certain hematologic parameters in adults. Methods: We pooled data from our two separate clinical trials and made five experimental groups. As part of their usual diet, one group consumed 500 mL/day of yogurt drink fortified with 1000 IU of vitamin D (D-yogurt, n = 27) whereas one group consumed 500 mL/day of the plain yogurt drink (P-yogurt, n = 27). In addition three other groups consumed either 50 g/day bread fortified with 1000 IU of vitamin D (D-bread) or supplement containing 1000 IU vitamin D (D-supplement, n = 27) or placebo (placebo, n = 27). Biochemical measurements were performed before and after the intervention. Results: In all three vitamin D-supplemented groups, serum 25(OH)D concentration increased after the intervention period, which was interestingly accompanied by a significant increment of hemoglobin (D-yogurt, p < 0.001, D-bread, p = 0.003, D-supplement, p < 0.001). Analyses indicated that among participants in vitamin D-intervention groups, being in D-yogurt group was more favourable predictor of improvement in hemoglobin concentrations compared with the placebo (p < 0.001), D-bread (p = 0.045) and P-yogurt (p = 0.001). Conclusion: Improvement of vitamin D status via regular intake of either vitamin D-fortified food products or supplements can result in a significant increment of hemoglobin in adult subjects. This finding has very important clinical as well as public health implications.

Effects of vitamin D prophylaxis on oral irontreatments of iron deficiency anemia

BACKGROUND

Iron deficiency anemia causes a decrease in immune response to infections, physical working capacity and response to metabolic stress. It also causes behavioral, perceptual and cognitive disorders. Therefore, as soon as iron deficiency anemia is diagnosed, it should be treated immediately. In this study, it was investigated retrospectively whether there was a difference in treatment efficacy between the administration of oral ferrous or ferric iron and vitamin D at the same time and at different time.

METHODS

A total of sixty patients under 1 year who attended the pediatrics outpatient clinic for pale and diagnosed with iron deficiency anemia. Patients were randomly divided into 4 groups. Anemia was defined as hemoglobin below <2 SD according to age and gender. Iron deficiency was definied with serum iron, iron-binding capacity, ferritin and transferin saturation below the range for age and gender appropriates. All patients were seen at the outpatient clinic for 1st, 3rd month of the treatment.

RESULTS

There were statistically significant differences between the groups in terms of increase in Hb values according to time (1^st month, 3^rd month, 1^st and 3^rd month). There was no statistically significant difference between the groups in terms of the recovery of anemia after treatment.

CONCLUSIONS

It was concluded that iron treatment in babies with iron deficiency anemia is not affected by the administration of vitamin D prophylaxis at the same time or at different times, and therefore both treatments can be administered at the same time to increase drug compliance.

Vitamin D levels among children, adolescents, adults, and elders in Pakistani population: a cross-sectional study

Background

Vitamin D is not only an essential part of a healthy diet but it is also known as the sunshine hormone. It helps to absorb calcium and phosphate within the body and is essential for the development of teeth and bones in growing children. Deficiency in vitamin D causes weak bones, osteoporosis in older individuals, and osteomalacia in children. It also causes loss of alveolar bone around the teeth, increased dental cavities, and other problems associated with gum disease. It can cause depression, fatigue, and appetite loss. This study aims to observe vitamin D deficiency, insufficiency, and sufficiency among children, adults, adolescents, and elders in the Pakistani population.

Methods

A cross-sectional survey was conducted with 27,880 individuals referred from the general out-patient-department (OPD) to Dow Diagnostic Research and Reference Laboratory (DDRRL) units at Dow University of Health Sciences (DUHS) Karachi, Pakistan, for a period of three months from January to March 2017. They were examined for laboratory findings of serum 25 hydroxyvitamin D levels to determine vitamin D deficiency, insufficiency, and sufficiency among all age groups of both male and female genders.

Results

A total of 26,750 individuals with a mean age of 38 ± 18 years were statistically examined for laboratory findings of serum vitamin D levels. Vitamin D deficiency was observed in 56% of individuals with a mean log of 1.01 ± 0.18 ng/ml serum vitamin D levels, vitamin D insufficiency in 20% of individuals with a mean log of 1.38 ± 0.05 ng/ml serum vitamin D levels and vitamin D sufficiency in 24% individuals with a mean log of 1.63 ± 0.12 ng/ml serum vitamin D levels. The highest percentage of individuals deficient in vitamin D were children and adolescents of age ranging between 6 to 18 years.

Conclusion

The findings of vitamin D deficiency in children and adolescents direct higher authorities in the public health sector to take immediate steps to screen, intervene and educate high-risk populations incorporating vitamin D supplements to establish preventive and therapeutic measures.

Vitamin D Deficiency Association with Comorbid Diseases in Palestine: "A Cross-Sectional Observation Study"

BACKGROUND

Vitamin D deficiency (VDD) is a global health concern. This study aimed to determine the prevalence of vitamin D deficiency and its associated comorbidities in Palestine, such as diabetes mellitus, hypertension, hyperlipidemia, and cardiovascular and autoimmune diseases.

METHODS

A retrospective, descriptive study retrieved medical data from the Nat Health insurance processor database from 2014 to 2020. Patient information included age, sex, vitamin D laboratory order, symptoms, and comorbidities. This study included patients prescribed vitamin D at a dose of 50000IU for vitamin D deficiency confirmed by a serum vitamin D laboratory test. The collected data were analyzed using IBM SPSS. In addition, a chi-square test was conducted to assess the association between vitamin D deficiency, symptoms, and comorbidities.

RESULTS

Data of 3011 patients were collected; 639 patients were diagnosed with osteoporosis, and 39 patients prescribed vitamin D without a laboratory test were excluded. Approximately, 1837 (78%) participants had vitamin D deficiency. A total of 1330 women (81.3%) were significantly more likely to have vitamin D deficiency than males, 507 (72.7%; P < 0.001). Joint pain, back pain, and cervicalgia were significantly associated with vitamin D deficiency (P < 0.001). Asymptomatic participants (2.1%) were significantly less likely to have vitamin D deficiency than symptomatic participants (9.5%, p < 0.001). Hypothyroidism is significantly associated with vitamin D deficiency (p = 0.048).

CONCLUSION

In this retrospective study, the prevalence of vitamin D was high and alarming. There was a significant association between VDD, patients who presented with back pain, arthritis, and cervicalgia symptoms, and patients diagnosed with hypothyroidism. Therefore, health initiative programs are warranted to increase awareness regarding screening, prevention, and treatment. Further studies are needed to confirm the relationship between vitamin D supplementation and the reduced risk of comorbid diseases.

Influences of Vitamin D and Iron Status on Skeletal Muscle Health: A Narrative Review

There is conflicting evidence of the roles vitamin D and iron have in isolation and combined in relation to muscle health. The purpose of this narrative review was to examine the current literature on the roles that vitamin D and iron have on skeletal muscle mass, strength, and function and how these nutrients are associated with skeletal muscle health in specific populations. Secondary purposes include exploring if low vitamin D and iron status are interrelated with skeletal muscle health and chronic inflammation and reviewing the influence of animal-source foods rich in these nutrients on health and performance. PubMed, Scopus, SPORT Discus, EMBAE, MEDLINE, and Google Scholar databases were searched to determine eligible studies. There was a positive effect of vitamin D on muscle mass, particularly in older adults. There was a positive effect of iron on aerobic and anaerobic performance. Studies reported mixed results for both vitamin D and iron on muscle strength and function. While vitamin D and iron deficiency commonly occur in combination, few studies examined effects on skeletal muscle health and inflammation. Isolated nutrients such as iron and vitamin D may have positive outcomes; however, nutrients within food sources may be most effective in improving skeletal muscle health.

Iron-Deficiency in Atopic Diseases: Innate Immune Priming by Allergens and Siderophores

Although iron is one of the most abundant elements on earth, about a third of the world's population are affected by iron deficiency. Main drivers of iron deficiency are beside the chronic lack of dietary iron, a hampered uptake machinery as a result of immune activation. Macrophages are the principal cells distributing iron in the human body with their iron restriction skewing these cells to a more pro-inflammatory state. Consequently, iron deficiency has a pronounced impact on immune cells, favoring Th2-cell survival, immunoglobulin class switching and primes mast cells for degranulation. Iron deficiency during pregnancy increases the risk of atopic diseases in children, while both children and adults with allergy are more likely to have anemia. In contrast, an improved iron status seems to protect against allergy development. Here, the most important interconnections between iron metabolism and allergies, the effect of iron deprivation on distinct immune cell types, as well as the pathophysiology in atopic diseases are summarized. Although the main focus will be humans, we also compare them with innate defense and iron sequestration strategies of microbes, given, particularly, attention to catechol-siderophores. Similarly, the defense and nutritional strategies in plants with their inducible systemic acquired resistance by salicylic acid, which further leads to synthesis of flavonoids as well as pathogenesis-related proteins, will be elaborated as both are very important for understanding the etiology of allergic diseases. Many allergens, such as lipocalins and the pathogenesis-related proteins, are able to bind iron and either deprive or supply iron to immune cells. Thus, a locally induced iron deficiency will result in immune activation and allergic sensitization. However, the same proteins such as the whey protein beta-lactoglobulin can also transport this precious micronutrient to the host immune cells (holoBLG) and hinder their activation, promoting tolerance and protecting against allergy. Since 2019, several clinical trials have also been conducted in allergic subjects using holoBLG as a food for special medical purposes, leading to a reduction in the allergic symptom burden. Supplementation with nutrient-carrying lipocalin proteins can circumvent the mucosal block and nourish selectively immune cells, therefore representing a new dietary and causative approach to compensate for functional iron deficiency in allergy sufferers.

Is There An Association Between Vitamin B12 Level and Vitamin D Status in Children?

Vitamin B12 (vit B12) or cobalamin is a water-soluble vitamin that acts as a coenzyme and is effective in the formation of a healthy nervous system and erythrocytes. In its deficiency, except fatigue and weakness, may cause serious signs and symptoms such as macrocytic anemia, cognitive-developmental delay, irreversible neurological damage. In this study, hemoglobin, leukocyte, thrombocyte, iron, iron-binding, ferritin, and vit B12 levels were evaluated retrospectively during the routine controls of 689 children 5 to 18 years old without any complaints. In addition, the relationship between serum 25-Hydroxyvitamin D (vit D) levels and vit B12 levels, which were evaluated in 487 of the cases, was investigated. Vit B12 deficiency was diagnosed in a total of 160 (23.2%) cases, 99 (24.4%) girls and 61 (21.4%) boys. Vit B12 level was significantly lower in children over 12 years old. Vitamin D deficiency was found to be 49.3% in 487 cases and was significantly higher in the group under 12 years and girls. The frequency of anemia was 7.2% in this group. There was a significant relationship between vit D deficiency and vit B12 deficiency. In conclusion, vit B12 deficiency is common in school-age children, especially in the adolescent age group. It should be known that vit D deficiency may also be present in vit B12 deficiency cases. More comprehensive studies are needed to reveal the relationship between B12 and vit D deficiency.

Vitamin D Deficiency and Its Association with Iron Deficiency in African Children

Vitamin D regulates the master iron hormone hepcidin, and iron in turn alters vitamin D metabolism. Although vitamin D and iron deficiency are highly prevalent globally, little is known about their interactions in Africa. To evaluate associations between vitamin D and iron status we measured markers of iron status, inflammation, malaria parasitemia, and 25-hydroxyvitamin D (25(OH)D) concentrations in 4509 children aged 0.3 months to 8 years living in Kenya, Uganda, Burkina Faso, The Gambia, and South Africa. Prevalence of iron deficiency was 35.1%, and prevalence of vitamin D deficiency was 0.6% and 7.8% as defined by 25(OH)D concentrations of <30 nmol/L and <50 nmol/L, respectively. Children with 25(OH)D concentrations of <50 nmol/L had a 98% increased risk of iron deficiency (OR 1.98 [95% CI 1.52, 2.58]) compared to those with 25(OH)D concentrations >75 nmol/L. 25(OH)D concentrations variably influenced individual markers of iron status. Inflammation interacted with 25(OH)D concentrations to predict ferritin levels. The link between vitamin D and iron status should be considered in strategies to manage these nutrient deficiencies in African children.

Ameliorating Atopy by Compensating Micronutritional Deficiencies in Immune Cells: A Double-Blind Placebo-Controlled Pilot Study

BACKGROUND

Functional iron deficiency facilitates allergy development and amplifies the symptom burden in people experiencing allergies. Previously we selectively delivered micronutrients to immune cells with β-lactoglobulin as carrier (holoBLG), resulting in immune resilience and allergy prevention.

OBJECTIVE

The clinical efficacy of a food for special medical purposes-lozenge containing β-lactoglobulin with iron, polyphenols, retinoic acid, and zinc (holoBLG lozenge) was assessed in allergic women.

METHODS

In a randomized, double-blind, placebo-controlled pilot study, grass- and/or birch pollen-allergic women (n = 51) were given holoBLG or placebo lozenges over 6 months. Before and after dietary supplementation, participants were nasally challenged and the blood was analyzed for immune and iron parameters. Daily symptoms, medications, pollen concentrations, and well-being were recorded by an electronic health application.

RESULTS

Total nasal symptom score after nasal provocations improved by 42% in the holoBLG group versus 13% in the placebo group. The combined symptom medication score during the birch peak and entire season as well as the entire grass pollen season improved in allergic subjects supplemented with the holoBLG lozenge by 45%, 31%, and 40%, respectively, compared with the placebo arm. Participants ingesting the holoBLG lozenge had improved iron status with increased hematocrit values, decreased red cell distribution width, and higher iron levels in circulating CD14⁺ cells compared with the placebo group.

CONCLUSIONS

Targeted micronutrition with the holoBLG lozenge seemed to be effective in elevating the labile iron levels in immune cells and reducing the symptom burden in allergic women in this pilot study. The underlying allergen-independent mechanism provides evidence that dietary nutritional supplementation of the immune system is one of the ways to combat atopy.

Dietary intake and nutritional status of Korean children and adolescents: a review of national survey data

In Korea, several national cross-sectional surveys monitor the diet, nutritional status, and health status of children. This continual dedicated national surveillance system contributes to the identification of nutritional and health issues, establishment of public health policies, and development of nutrition recommendations. This paper provides recent information about the Korea National Health and Nutrition Examination Survey and the Korean Youth Risk Behavior Web-based Survey and describes key nationwide survey findings published in the last 5 years on infant feeding practices and the dietary intake and nutritional status of Korean infants, children, and adolescents. There have been increasing trends in children, and teenagers who skip breakfast, eat fast food, consume sugary drinks, have vitamin D deficiency, and are obese. This review will inform pediatricians, nutritionists, and other health care practitioners who track children's growth and development. It may also help researchers and policymakers identify diet-related policies and strategies for chronic disease prevention in Korean infants, children, and adolescents.

Pulse Probiotic Superfood as Iron Status Improvement Agent in Active Women-A Review

Active women or women of reproductive age (15–49 years old) have a high risk of suffering from anaemia. Anaemia is not solely caused by iron deficiency, however, the approaches to improve iron status in both cases are greatly related. Improving the iron status of active women can be done by dietary intervention with functional food. This review aims to provide insights about the functional food role to increase iron absorption in active women and the potency of pulse probiotic superfood development in dry matrices. Results showed that the beneficial effect of iron status is significantly improved by the synergic work between probiotic and prebiotic. Furthermore, chickpeas and lentils are good sources of prebiotic and the consumption of pulses are related with 21st century people’s intention to eat healthy food. There are wide possibilities to develop functional food products incorporated with probiotics to improve iron status in active woman.

The Association Between Ferritin and Vitamin D Levels in Premenopausal Fibroid Uterus Cases With Anemia

Objective

The present study aimed to evaluate the association between serum ferritin and vitamin D levels in fibroid uterus cases presenting with anemia.

Methods

Sixty premenopausal women with uterine fibroids (30 associated with anemia and 30 without anemia) were enrolled as cases and control. All participants were evaluated on the basis of a questionnaire, which included queries related to obstetric, medical, and sociodemographic history. Peripheral blood smear, complete blood count (CBC), hemoglobin (Hb), and serum ferritin concentration were measured by a fully automated analyzer, and 25(OH) vitamin D level was measured by enzyme-linked immunosorbent assay (ELISA).

Results

There was a significant difference in ferritin levels between cases and control (p<0.001). The exposure to sunlight was moderate (one-hour exposure) in all subjects, eliminating the confounding effect of sunlight exposure influencing vitamin D levels. The median vitamin D level in cases was 5.0 ng/ml [interquartile range (IQR): 4.8], and that in control was 18.4 ng/ml (IQR: 7.9; p<0.001). A strong positive correlation of (r)=0.616 (p<0.001) was found between serum ferritin and vitamin D levels.

Conclusion

Fibroid uterus cases with anemia are more prone to vitamin D deficiency as compared to cases without anemia. Vitamin D estimation in fibroid uterus cases presenting with anemia would be useful for better patient management.

Vitamin D Deficiency in Middle Childhood Is Related to Behavior Problems in Adolescence

BACKGROUND

Vitamin D deficiency (VDD) is associated with depression and schizophrenia in adults. The effect of VDD in childhood on behavioral development is unknown.

OBJECTIVES

We aimed to study the associations of VDD and vitamin D binding protein (DBP) in middle childhood with behavior problems in adolescence.

METHODS

We quantified plasma total 25-hydroxyvitamin D [25(OH)D] and DBP in 273 schoolchildren aged 5-12 y at recruitment into a cohort study in Bogota, Colombia. Externalizing and internalizing behavior problems were assessed after a median 6-y follow-up by parental report [Child Behavior Checklist (CBCL)] and self-report [Youth Self-Report (YSR)]. We estimated mean problem score differences with 95% CIs between exposure categories using multivariable linear regression. We also compared the prevalence of clinical behavior problems (score >63) between exposure groups. We assessed whether the associations between DBP and behavior problems were mediated through VDD.

RESULTS

Mean ± SD CBCL and YSR externalizing problems scores were 56.5 ± 9.3 and 53.2 ± 9.5, respectively. Internalizing problems scores averaged 57.1 ± 9.8 and 53.7 ± 9.8, respectively. VDD [25(OH)D <50 nmol/L] prevalence was 10.3%. VDD was associated with an adjusted 6.0 (95% CI: 3.0, 9.0) and 3.4 (95% CI: 0.1, 6.6) units higher CBCL and YSR externalizing problems scores, respectively, and an adjusted 3.6 (95% CI: 0.3, 6.9) units higher CBCL internalizing problems scores. The prevalence of clinical total externalizing problems was 1.8 (95% CI: 1.1, 3.1) times higher in children with VDD than that in children without VDD. DBP concentration below the population median was related to higher YSR aggressive behavior and anxious/depressed subscale scores and to higher prevalence of clinical total externalizing problems. The associations between DBP and behavior problems were not mediated through VDD.

CONCLUSIONS

VDD and low DBP in middle childhood are related to behavior problems in adolescence.

Vitamin D Decreases Hepcidin and Inflammatory Markers in Newly Diagnosed Inflammatory Bowel Disease Paediatric Patients: A Prospective Study

BACKGROUND AND AIMS

The role of hepcidin in inflammatory bowel disease [IBD] in children with anaemia is poorly understood. However, it has been shown that vitamin D suppresses hepcidin expression. We aimed to assess serum hepcidin levels and the effect of vitamin D treatment on those levels in newly diagnosed IBD paediatric patients.

METHODS

Eighty-five children were prospectively recruited in the Dana-Dwek Children's Hospital [40 newly diagnosed IBD, 45 healthy controls, 47% female, mean age 13.5 ± 3.4 years]. Blood samples for measurement of interleukin 6 [IL-6], C-reactive protein [CRP], hepcidin, iron parameters and 25-hydroxyvitamin D [25-(OH)-D] levels were obtained at baseline. Patients with mild-to-moderate signs and symptoms of IBD were treated with 4000 units of vitamin D daily for 2 weeks, after which the blood tests were repeated.

RESULTS

Basal hepcidin, IL-6, CRP and platelet counts were significantly higher, and haemoglobin, serum iron and transferrin levels were significantly lower in the IBD children compared to controls [p < 0.001]. Eighteen patients completed 2 weeks of treatment with vitamin D. Following treatment, serum 25-(OH)-D concentrations increased by 40% [from 22.5 to 32.5 ng/mL], and serum hepcidin, CRP and ferritin levels decreased by 81%, 81% and 40% [from 33.9 to 6.7 ng/mL, from 23.9 to 4.7 mg/L, and from 27 to 16 ng/mL, respectively] [p ≤ 0.001].

CONCLUSION

Serum hepcidin levels were significantly higher in IBD paediatric patients compared to controls. Following vitamin D treatment, serum hepcidin concentration decreased significantly. These findings suggest a potential role for vitamin D in treating anaemia in IBD children.

CLINICALTRIALS.GOV NUMBER

NCT03145896.

Vitamin D Status in Egyptian Adolescent Females with Iron Deficiency Anemia and Its Correlation with Serum Iron Indices

Background:

In Egypt, it seems that adolescent girls are a candidate for Vitamin D Deficiency (VDD), mostly due to inadequate sun exposure as a result of the culture and social dress codes and dietary factors. Currently, there is growing evidence that VDD is associated with Iron Deficiency Anemia (IDA).

Aim:

To investigate the frequency of VDD in adolescent females with IDA in comparison to healthy control and demonstrate whether VD level was correlated with serum iron indices.

Subjects and Methods:

Forty adolescent females with known cases of IDA (group 1) and 30 healthy females matched for age as a control (group 2) were selected. We compared the differences between the two groups to determine the degree of VD level; where VDD was defined as 25-hydroxyvitamin D [25(OH)D] ≤20 ng/mL, vitamin D insufficiency (VDI) as 25(OH) D of 20-30 ng/mL, and vitamin D sufficiency (VDS) as 25(OH)D >30 ng/mL. Body mass index (BMI), complete blood count (CBC), serum iron, total iron binding capacity (TIBC), serum ferritin, serum creatinine, ionized calcium and 25(OH)D were measured for all participants.

Results:

We found that subnormal vitamin D (VDD and VDI) was more frequent in the IDA group (75%) than control (40%), (p = 0.025); where 19 adolescent female patients (47.5%) were VDD, 11 (27.5%) were VDI and 10 (25%) were VDS, while in the control group, VDD was present in 4 (20%), VDI in 4 (20%) and VDS in 12 (60%) respectively. There was not any significant correlation between serum VD and serum iron indices (r =0.168, p < 0.05) and Hb (r = 0.360, p < 0.001). There was no significant difference in serum hemoglobin level between IDA patients with subnormal VD and those with VDS. The mean level of serum 25(OH) D was significantly lower in winter months than summer in both groups; (16.87 vs. 31.57 mg/dL, p < 0.001) and (31.9 vs. 35.04 mg/dL, p < 0.001) respectively. BMI, Iron, TIBC and seasonal variation were not predictors of 25(OH) D levels in adolescent girls with IDA.

Conclusion:

VDD has a higher frequency in Egyptian adolescent females with IDA than healthy control. However, vitamin D levels were not significantly correlated with iron indices. Our result might direct the attention for measuring vitamin D level in patients with IDA with the possibility of VD supplementation with iron.

The association of serum 25-hydroxyvitamin D concentrations with elevated serum ferritin levels in normal weight, overweight and obese Canadians

In light of the growing body of literature suggesting a beneficial effect of vitamin D on inflammatory response, we hypothesized that vitamin D affects serum ferritin (SF), a biomarker of inflammation. The objective of the present study is to examine the association of serum 25-hydroxyvitamin D [25(OH)D] with elevated SF concentrations indicative of inflammation as no earlier study has done so. Data from 5550 Canadian adults who participated in the 2012/2013 and the 2014/2015 Canadian Health Measures Surveys were analysed. We observed that 9.4% of Canadian adults have elevated SF concentrations and that 35.6% were vitamin D insufficient. Among Canadians with under/normal body weights, those with serum 25(OH)D ≥ 75 nmol/L relative to those with serum 25(OH)D < 50 nmol/L, were substantially less at risk for elevated SF concentrations (OR = 0.24; 95% CI = 0.06, 0.89; p = 0.034). We did not observe this association for overweight and obese Canadians. Canadians of older age, non-white ethnicity, males, those with income above $100,000, those who consumed alcohol, and those with high total cholesterol concentrations and elevated blood pressures were more likely to have elevated SF concentrations. Serum 25(OH)D ≥ 75 nmol/L is likely to provoke anti-inflammatory benefits, but intervention studies that achieve high 25(OH)D concentrations and with long follow up are needed to establish the role of vitamin D on SF.

The interrelationship between hepcidin, vitamin D, and anemia in children with acute infectious disease

BACKGROUND

Hepcidin is a master regulator of iron metabolism. Recently, it has been shown that vitamin D suppresses hepcidin expression. Our hypothesis was that hepcidin levels inversely correlate with vitamin D levels in anemic children during acute infection.

METHODS

A prospective study was performed on 90 patients (45 females, 45 males, mean age 7.3 ± 5 years) who were admitted to the pediatric ward. Sixty-two patients had infectious disease (32 with coexisting anemia, 30 without anemia), and 28 patients were hospitalized for noninfectious causes. Blood samples for IL-6, hepcidin, iron status parameters, and 25-hydroxyvitamin D (25-OHD) were obtained within 72 h after admission.

RESULTS

Serum concentrations of IL-6 and hepcidin were significantly higher and 25-OHD, iron, and transferrin were significantly lower in anemic children with infectious disease compared with controls. Children with a serum 25-OHD level < 20 ng/ml had significantly increased odds of having anemia than those with a level > 20 ng/ml (OR: 6.1, CI: 1.15-32.76). Correlation analyses found positive associations between hepcidin levels and ferritin (R² = 0.47, P < 0.001) and negative associations between hepcidin and transferrin (R² = 0.57, P < 0.001).

CONCLUSION

Higher IL-6 and lower 25-OHD levels may lead to higher hepcidin levels and subsequently to hypoferremia and anemia in children with acute infection.

Correlates and predictors of paediatric leg pain: a case-control study

Paediatric leg pains, long described as 'growing pains', frequently present to clinicians, are prevalent in early childhood, disrupt sleep, and distress affected children and parents. There are many cited associations, but no defined leg pain sub-types, nor revealed predictive factors. We explored the implicated factors (viz. foot arches, foot strength, joint mobility, vitamin D, iron) in children with leg pain versus a control group. Leg pain sub-groups-growing pains (GP), restless legs (RLS), both (mixed)-are defined for the first time. A case controlled study design, in a primary care setting, Mumbai, India. A total of 77 children with leg pains (n = 64) and controls (n = 13), aged 3-12 years, identified by paediatricians, completed data collection. Blood assays for iron and vitamin D, pain, Beighton score, foot arch, foot strength and anthropometrical data were collected. All outcome measures were validated, with standardised protocols. Leg pain (all groups) was predicted by increased joint mobility and increased ankle dorsiflexion strength (β = 0.56, P < 0.05). GP sub-group was predicted by increased ankle dorsiflexion strength (β = - 0.06, P < 0.05). Mixed (GP/RLS) and RLS sub-groups were predicted by increased ankle dorsiflexion strength (β = 0.66, P < 0.05) and pain questionnaire (β = 0.11, P < 0.05). Hypovitaminosis D was detected in 87% of the sample, and anaemia in 13%. Increased strength of ankle dorsiflexors and joint flexibility were each found predictive for leg pain. Increased body weight, waist girth, and BMI were all associated with leg pain.

Reference values for serum ferritin and percentage of transferrin saturation in Korean children and adolescents

Background

Ferritin reference values vary by age, gender, and ethnicity. We aimed to determine reference values of serum ferritin (SF) and the percentage of transferrin saturation (TSAT) for Korean children and adolescents.

Methods

We analyzed data from 2,487 participants (1,311 males and 1,176 females) aged 10-20 years from the Korea National Health and Nutrition Examination Survey (2010-2012). We calculated age- and gender-stratified means and percentile values for SF and TSAT.

Results

We first plotted mean SF and TSAT by gender and according to age. In males, mean SF tended to be relatively constant among participants aged 10 to 14 years, with an upward trend thereafter. Mean SF trended downward among female participants until the age of 15 years and remained constant thereafter. Thus, significant gender differences in ferritin exist from the age of 14 years. High levels of SF were associated with obesity, and lower SF levels were associated with anemia and menarche status.

Conclusion

We established reference values of SF and TSAT according to age and gender. The reference values for SF calculated in this study can be used to test the association between SF values and other defined diseases in Korean children and adolescents.

The Association between Iron and Vitamin D Status in Female Elite Athletes

Vitamin D may influence iron metabolism and erythropoiesis, whereas iron is essential for vitamin D synthesis. We examined whether vitamin D deficiencies (VDD) are associated with reduced iron status and whether progressive iron deficiency (ID) is accompanied by inferior vitamin D status. The study included 219 healthy female (14–34 years old) athletes. VDD was defined as a 25(OH)D concentration < 75 nmol/L. ID was classified based on ferritin, soluble transferrin receptor (sTfR), total iron binding capacity (TIBC) and blood morphology indices. The percentage of ID subjects was higher (32%) in the VDD group than in the 25(OH)D sufficient group (11%) (χ² = 10.6; p = 0.001). The percentage of VDD subjects was higher (75%) in the ID than in the normal iron status group (48%) (χ² = 15.6; p = 0.001). The odds ratios (ORs) for VDD increased from 1.75 (95% CI 1.02–2.99; p = 0.040) to 4.6 (95% CI 1.81–11.65; p = 0.001) with progressing iron deficiency. ID was dependent on VDD in both VDD groups (25(OH)D < 75 and < 50 nmol/L). The ID group had a lower 25(OH)D concentration (p = 0.000). The VDD group had lower ferritin (p = 0.043) and iron (p = 0.004) concentrations and higher values of TIBC (p = 0.016) and sTfR (p = 0.001). The current results confirm the association between vitamin D and iron status in female athletes, although it is difficult to assess exactly which of these nutrients exerts a stronger influence over the other.

Poor vitamin D status increases the risk of anemia in school children: National Food and Nutrition Surveillance

OBJECTIVES

This study aimed to investigate the association between 25-hydroxyvitamin D (25[OH]D) concentrations and the risk of anemia in a large cohort of children with consideration for the effects of sex, body mass index (BMI), serum intact parathyroid hormone (iPTH) concentrations, and iron level status.

METHODS

A total of 937 children (493 boys, 444 girls) ages 9 to 12 y were enrolled in a cross-sectional study. The children underwent various examinations including anthropometric measurements and blood sampling.

RESULTS

Overall, 13.3% of the children were anemic and 64.2% and 28.1% of the subjects had a vitamin D deficiency (<25 nmol/L) and insufficiency (25-50 nmol/L), respectively. Approximately 13% of the children had concurrent low hemoglobin and hypovitaminosis D levels. The prevalence of hypovitaminosis D in the group of children with anemia was 96.8% compared with 91.6% in the non-anemic group (P = 0.046). Mean 25(OH)D concentrations were significantly lower in the anemic children compared with the non-anemic children (19.6 ± 13.3 vs. 24.0 ± 23.1 nmol/L; P = 0.003). After controlling for sex and BMI, children with a vitamin D deficiency were almost 3.45 times more likely to be anemic compared with children with a vitamin D sufficiency (95% confidence interval [CI], 1.21-9.81). The increased risk of anemia was found to start significantly at 25(OH)D < 44 nmol/L (17.6 ng/mL; odds ratio: 2.29; 95% CI, 1.07-4.91, P = 0.032).

CONCLUSIONS

These findings strongly suggest an association between low circulating concentrations of 25(OH)D and anemia in a large, representative sample of children, even after adjustment for sex, age, BMI, and iPTH.

The association between serum ferritin and 25-hydroxyvitamin D and metabolic syndrome in Korean women: the Korea National Health and Nutrition Examination Survey 2010-2012

The present study was conducted to assess the association between serum ferritin and 25-hydroxyvitamin D [25(OH)D] and metabolic syndrome (MetS) in Korean women. The data of a total of 9,256 adults (6,960 women without MetS and 2,296 women with MetS) aged ≥20 years from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES V) (2010–2012) were analyzed. A covariance test adjusted for covariates was performed for serum ferritin levels in relation to vitamin D (vitamin D deficiency, 25(OH)D <10.0 ng/ml; vitamin D insufficiency, 25(OH)D ≥10.0, <20.0 ng/ml; vitamin D sufficiency, 25(OH)D ≥20.0 ng/ml). The key study results were as follows: First, in women without MetS, after adjusting for related variables (smoking, alcohol drinking, regular exercise, current menstruation, hormonal contraceptives, hormone-replacement therapy, SBP, DBP, BMI, WM, TC, TGs, HDL-C, FPG, AST, ALT, and age), vitamin D was positively associated with serum ferritin levels (p<0.001). Second, in women with MetS, after adjusting for related variables (except age), vitamin D was positively associated with serum ferritin levels (p = 0.041). However, when further adjusted for age, vitamin D was not associated with serum ferritin levels (p = 0.293). In conclusion, vitamin D was positively associated with serum ferritin levels in women without MetS but not in women with MetS.

The association between serum ferritin and 25-hydroxyvitamin D and metabolic syndrome in Korean women: the Korea National Health and Nutrition Examination Survey 2010-2012

The present study was conducted to assess the association between serum ferritin and 25-hydroxyvitamin D [25(OH)D] and metabolic syndrome (MetS) in Korean women. The data of a total of 9,256 adults (6,960 women without MetS and 2,296 women with MetS) aged ≥20 years from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES V) (2010-2012) were analyzed. A covariance test adjusted for covariates was performed for serum ferritin levels in relation to vitamin D (vitamin D deficiency, 25(OH)D <10.0 ng/ml; vitamin D insufficiency, 25(OH)D ≥10.0, <20.0 ng/ml; vitamin D sufficiency, 25(OH)D ≥20.0 ng/ml). The key study results were as follows: First, in women without MetS, after adjusting for related variables (smoking, alcohol drinking, regular exercise, current menstruation, hormonal contraceptives, hormone-replacement therapy, SBP, DBP, BMI, WM, TC, TGs, HDL-C, FPG, AST, ALT, and age), vitamin D was positively associated with serum ferritin levels (p<0.001). Second, in women with MetS, after adjusting for related variables (except age), vitamin D was positively associated with serum ferritin levels (p = 0.041). However, when further adjusted for age, vitamin D was not associated with serum ferritin levels (p = 0.293). In conclusion, vitamin D was positively associated with serum ferritin levels in women without MetS but not in women with MetS.

Gender difference in relationship between serum ferritin and 25-hydroxyvitamin D in Korean adults

BACKGROUND

The present study was conducted to assess the gender difference in the relationship between serum ferritin and 25-hydroxyvitamin D [25(OH)D] in Korean adults.

METHODS

A total of 5,147 adults (2,162 men, 1,563 premenopausal women, and 1,422 postmenopausal women) aged ≥ 20 years from the Korean National Health and Nutrition Examination Survey (KNHANES) data (2012) were analyzed. A covariance test adjusted for covariates was performed for serum ferritin levels in relation to vitamin D status (vitamin D deficiency, 25(OH)D < 10.0 ng/mL; vitamin D insufficiency, 25(OH)D ≥ 10.0, < 20.0 ng/mL; vitamin D sufficiency, 25(OH)D ≥ 20.0 ng/mL).

RESULTS

The key study results were as follows: First, in men, in terms of serum ferritin levels by serum 25(OH)D level after adjusting for age, smoking, alcohol drinking, regular exercise, SBP, DBP, WM. TC, TGs, HDL-C, FPG, Hb, Hct, MCV, and Fe, serum ferritin levels were inversely increased with the increasing of serum 25(OH)D level (P = 0.012). Second, in premenopausal women, after adjusting for related variables, serum ferritin levels were increased with the increasing of serum 25(OH)D level (P = 0.003). Third, in postmenopausal women, after adjusting for related variables, serum ferritin levels were not significantly increased with the increasing of serum 25(OH)D level (P = 0.456).

CONCLUSION

Serum 25(OH)D level was inversely associated with the serum ferritin levels in men, but was positively associated with the serum ferritin levels in premenopausal women, and was not associated with the serum ferritin levels in postmenopausal women.

Vitamin D deficiency and anemia risk in children: a review of emerging evidence

There has been renewed scientific interest in the sequelae of vitamin D deficiency, given the emerging evidence on the diverse biologic functions of vitamin D, besides its fundamental role in bone and mineral metabolism. For the past decade, the evidence in the medical literature pointing to a relationship between anemia risk and vitamin D deficiency has been accumulating. This paper critically reviews the current evidence linking vitamin D deficiency to anemia risk in children. The synthesized evidence indicates that the studies, which were preponderantly conducted among the adult population, not only reported a bidirectional relationship between vitamin D deficiency and anemia but also showed a racial effect. In studies conducted among children, similar results were reported. Although the causal association of vitamin D deficiency with anemia risk (especially iron-deficiency anemia) remains debatable, the noncalcemic actions of the vitamin and its analogs hold prospects for several novel clinical applications. There is, however, unanimity in many reports suggesting that vitamin D deficiency is directly associated with anemia of chronic disease or inflammation. Despite the advances in unraveling the role of vitamin D in iron homeostasis, further research is still required to validate causality in the relationship between vitamin D deficiency and anemia, as well as to determine its optimal dosing, the ideal recipients for therapeutic intervention, and the preferred analogs to administer.

A micronutrient-fortified young-child formula improves the iron and vitamin D status of healthy young European children: a randomized, double-blind controlled trial

BACKGROUND

Iron deficiency (ID) and vitamin D deficiency (VDD) are common among young European children because of low dietary intakes and low compliance to vitamin D supplementation policies. Milk is a common drink for young European children. Studies evaluating the effect of milk fortification on iron and vitamin D status in these children are scarce.

OBJECTIVE

We aimed to investigate the effect of a micronutrient-fortified young-child formula (YCF) on the iron and vitamin D status of young European children.

DESIGN

In this randomized, double-blind controlled trial, healthy German, Dutch, and English children aged 1-3 y were allocated to receive either YCF (1.2 mg Fe/100 mL; 1.7 μg vitamin D/100 mL) or nonfortified cow milk (CM) (0.02 mg Fe/100 mL; no vitamin D) for 20 wk. Blood samples were taken before and after the intervention. The primary and secondary outcomes were change from baseline in serum ferritin (SF) and 25-hydroxyvitamin D [25(OH)D], respectively. ID was defined as SF <12 μg/L in the absence of infection (high-sensitivity C-reactive protein <10 mg/L) and VDD as 25(OH)D <50 nmol/L. Statistical adjustments were made in intention-to-treat analyses for sex, country, age, baseline micronutrient status, and micronutrient intake from food and supplements (and sun exposure in the case of vitamin D outcomes).

RESULTS

The study sample consisted of 318 predominantly Caucasian (∼95%) children. The difference in the SF and 25(OH)D change between the treatment groups was 6.6 μg/L (95% CI: 1.4, 11.7 μg/L; P = 0.013) and 16.4 nmol/L (95% CI: 9.5, 21.4 nmol/L; P < 0.001), respectively. The probability of ID (OR 0.42; 95% CI:0.18, 0.95; P = 0.036) and VDD (OR 0.22; 95% CI: 0.01, 0.51; P < 0.001) after the intervention was lower in the YCF group than in the CM group.

CONCLUSION

Micronutrient-fortified YCF use for 20 wk preserves iron status and improves vitamin D status in healthy young children in Western Europe. This trial was registered at www.trialregister.nl as NTR3609.

Association of maternal serum 25-hydroxyvitamin D concentrations in second and third trimester with risk of gestational diabetes and other pregnancy outcomes

OBJECTIVES

To evaluate the maternal serum 25(OH)D concentrations and its association with gestational diabetes and other pregnancy outcomes.zMethods:In our nested case-control study, 4718 pregnancy women were included, who were attending second- and third-trimester screening in Nanjing, China. Serum 25(OH)D concentrations were tested by enzyme-linked immunoassay, and the pregnancy and birth outcomes were obtained via electronic medical record collection and information extraction. The associations of 25(OH)D concentrations with gestational diabetes and other pregnancy outcomes were assessed by logistic regression analysis. And receiver-operator characteristic curve analysis was also conducted.

RESULTS

For the total population, the median (IQR) concentrations of 25(OH)D was 43.7 (35.5-57.9) nmol l^-1, and 63.1% of women had concentrations <50.0  nmol l^-1. The 25(OH)D concentrations was significantly lower in gestational diabetes patients than in controls. Moreover, after adjustment for confounders, women with low 25(OH)D concentrations had significantly increased risks of gestational diabetes and some adverse pregnancy outcomes (anemia, macrosomia, abnormal amniotic fluid, and miscarriage or stillbirth). We also observed a threshold for 25(OH)D of 50.0 nmol l^-1 for gestational diabetes and a nice predictive accuracy of the 25(OH)D concentrations included panel, with an area under the curve of 0.625 for gestational diabetes.

CONCLUSIONS

Low 25(OH)D concentrations (<50.0 nmol l^-1) in pregnancy was significantly associated with gestational diabetes risk, and it may serve as biomarkers for the surveillance of high-risk pregnant women.

Vitamin D3 transactivates the zinc and manganese transporter SLC30A10 via the Vitamin D receptor

Vitamin D3 regulates genes critical for human health and its deficiency is associated with an increased risk for osteoporosis, cancer, diabetes, multiple sclerosis, hypertension, inflammatory and immunological diseases. To study the impact of vitamin D3 on genes relevant for the transport and metabolism of nutrients and drugs, we employed next-generation sequencing (NGS) and analyzed global gene expression of the human-derived Caco-2 cell line treated with 500nM vitamin D3. Genes involved in neuropeptide signaling, inflammation, cell adhesion and morphogenesis were differentially expressed. Notably, genes implicated in zinc, manganese and iron homeostasis were largely increased by vitamin D3 treatment. An ∼10-fold increase in ceruloplasmin and ∼4-fold increase in haptoglobin gene expression suggested a possible association between vitamin D and iron homeostasis. SLC30A10, the gene encoding the zinc and manganese transporter ZnT10, was the chiefly affected transporter, with ∼15-fold increase in expression. SLC30A10 is critical for zinc and manganese homeostasis and mutations in this gene, resulting in impaired ZnT10 function or expression, cause manganese intoxication, with Parkinson-like symptoms. Our NGS results were validated by real-time PCR in Caco-2 cells, as well as in duodenal biopsies taken from healthy human subjects treated with 0.5μg vitamin D3 daily for 10 days. In addition to increasing gene expression of SLC30A10 and the positive control TRPV6, vitamin D3 also increased ZnT10 protein expression, as indicated by Western blot and cytofluorescence. In silico identification of potential vitamin D responsive elements (VDREs) in the 5'-flanking region of the SLC30A10 promoter and dual-luciferase reporter assay showed enhanced promoter activity in the presence of vitamin D receptor (VDR) and retinoid X receptor (RXR) constructs, as well as vitamin D3, but not when one of these factors was absent. Electrophoretic mobility shift assay (EMSA) and competition EMSA revealed binding of select sequences, namely, nt -1623/-1588 and nt -1758/-1723 relative to the transcription start site, to VDR-containing nuclear extracts. In conclusion, we have shown that vitamin D3 transactivates the SLC30A10 gene in a VDR-dependent manner, resulting in increased ZnT10 protein expression. Because SLC30A10 is highly expressed in the small intestine, it is possible that the control of zinc and manganese systemic levels is regulated by vitamin D3 in the intestine. Zinc, manganese and vitamin D are important for bone metabolism and brain health. Future examination of a possible role for supplementation or chelation of zinc and manganese, alongside vitamin D3 administration, will further our understanding of its potential benefit in the treatment of specific illnesses, such as osteoporosis and Parkinson's disease.

Serum Zinc Is a Major Predictor of Anemia and Mediates the Effect of Selenium on Hemoglobin in School-Aged Children in a Nationally Representative Survey in New Zealand

BACKGROUND

Zinc, selenium, and vitamin D status of New Zealand (NZ) school-aged children was examined in a national survey in 2002. To our knowledge, however, the role of these micronutrients as predictors of hemoglobin has not been explored despite plausible mechanisms for such relations.

OBJECTIVE

We examined the relations of iron, zinc, selenium, and vitamin D status with hemoglobin and anemia in children of New Zealand European and other (NZEO) ethnicity enrolled in the 2002 Children's Nutrition Survey and explored whether zinc mediated the relation between selenium and hemoglobin.

METHODS

Multivariate regression was performed to examine the relations of serum micronutrient biomarkers, acute inflammation, socioeconomic status, and body mass index (BMI) with hemoglobin and anemia of NZEO children aged 5-15 y (n = 503). A mediation analysis also investigated direct and indirect (through zinc) relations between selenium and hemoglobin.

RESULTS

In total, 4.6% of the children were anemic, 3.2% had depleted iron stores, and none had iron deficiency anemia. The prevalence of low serum zinc (<8.7-10.1 μmol/L depending on age and sex), selenium (<0.82 μmol/L), and 25-hydroxyvitamin D (<50 nmol/L) was 14.1%, 22.9%, and 48.5%, respectively. Major predictors of hemoglobin were serum zinc, age, and BMI-for-age z score (P < 0.001); log ferritin and being female were also statistically significant (P < 0.05). Selenium had an indirect effect that was mediated by zinc, with a significant effect of selenium on zinc (P = 0.002) and zinc on hemoglobin (P < 0.001). Zinc was the only variable associated with anemia risk (OR: 5.49; 95% CI: 1.95, 15.46).

CONCLUSIONS

Low serum zinc was an independent risk factor for anemia in NZEO school-aged children and mediated the effect of low selenium on hemoglobin. These findings emphasize the importance of considering multiple micronutrient deficiencies in addition to iron when interpreting anemia and of appreciating the mechanistic interactions that underlie these associations.

Effect of vitamin D3 supplementation on iron status: a randomized, double-blind, placebo-controlled trial among ethnic minorities living in Norway

BACKGROUND

Both vitamin D and iron deficiencies are widespread globally, and a relationship between these deficiencies has been suggested. However, there is a paucity of randomised controlled trials assessing the effect of vitamin D supplementation on iron status.

PURPOSE

We aimed to investigate whether 16 weeks of daily vitamin D3 supplementation had an effect on serum ferritin, haemoglobin, serum iron and transferrin saturation.

METHODS

Overall, 251 participants from South Asia, Middle East and Africa aged 18-50 years who were living in Norway were randomised to receive daily oral supplementation of 10 μg vitamin D3, 25 μg vitamin D3, or placebo for 16 weeks during the late winter. Blood samples from baseline and after 16 weeks were analysed for serum 25-hydroxyvitamin D (s-25(OH) D), serum ferritin, haemoglobin and serum iron. In total, 214 eligible participants completed the intervention (86 % of those randomised). Linear regression analysis were used to test the effect of vitamin D3 supplementation combined (10 or 25 μg) and separate doses 10 or 25 μg compared to placebo on change (T2-T1) in each outcome variable adjusted for baseline s-25(OH)D values.

RESULTS

There was no difference in change in the levels of s-ferritin (1.9 μg/L, 95 % CI: -3.2, 7.0), haemoglobin (-0.02 g/dL, 95 % CI: -0.12, 0.09), s-iron (0.4 μg/L, 95 % CI: -0.5, 1.3) or transferrin saturation (0.7 %, 95 % CI: -0.6.1, 2.0) between those receiving vitamin D3 or those receiving placebo. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after the intervention, with little change in the placebo group.

CONCLUSIONS

In this population of healthy ethnic minorities from South Asia, the Middle East and Africa who had low vitamin D status, 16 weeks of daily supplementation with 10 or 25 μg of vitamin D3 did not significantly affect the haemoglobin levels or other markers of iron status.

Independent associations of vitamin D metabolites with anemia in patients referred to coronary angiography: the LURIC study

PURPOSE

Anemia and vitamin D deficiency are both frequent in adult patients. Whether low vitamin D metabolite levels are an independent risk factor for different subtypes of anemia remains to be studied in detail.

METHODS

In 3299 patients referred for coronary angiography, we investigated the association of 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D [1,25(OH)₂D] with anemia [hemoglobin (Hb) <12.5 g/dl] of specific subtypes.

RESULTS

Compared with patients with 25OHD levels in the adequate range (50-125 nmol/l), patients with deficient 25OHD concentrations (<30 nmol/l; 33.6 % of patients) had 0.6 g/dl lower Hb levels. Hb values were 1.3 g/dl lower in patients with 1,25(OH)₂D levels <40 pmol/l (5.4 % of patients), compared with patients in the highest 1,25(OH)₂D category (>70 pmol/l). Of the participants, 16.7 % met the criteria for anemia. In multivariate-adjusted regression analyses, the odds ratios for anemia in the lowest 25OHD and 1,25(OH)₂D categories were 1.52 (95 % CI 1.15-2.02) and 3.59 (95 % CI 2.33-5.52), compared with patients with 25OHD levels in the adequate range and patients with 1,25(OH)₂D levels >70 pmol/l. The probability of anemia was highest in patients with combined 25OHD and 1,25(OH)₂D deficiency [multivariable-adjusted odds ratio 5.11 (95 % CI 2.66-9.81)]. Patients with anemia of chronic kidney disease had the highest prevalence of 25OHD deficiency and 1,25(OH)₂D concentrations of <40 pmol/l.

CONCLUSIONS

Low 25OHD and 1,25(OH)₂D concentrations are independently associated with anemia. Patients with poor kidney function are most affected. Interventional trials are warranted to prove whether administration of plain or activated vitamin D can prevent anemia.

Prevalence and Relationships of Iron Deficiency Anemia with Blood Cadmium and Vitamin D Levels in Korean Women

Anemia, iron deficiency (ID), and iron deficiency anemia (IDA) are common disorders. This study was undertaken to determine the prevalence of anemia, ID, and IDA in Korean females. We examined the associations between IDA, heavy metals in blood, vitamin D level and nutritional intakes. The study was performed using on data collected from 10,169 women (aged ≥ 10 yr), including 1,232 with anemia, 2,030 with ID, and 690 with IDA during the fifth Korea National Health and Nutrition Examination Survey (KNHANES V; 2010-2012). Prevalence and 95% confidence intervals were calculated, and path analysis was performed to identify a multivariate regression model incorporating IDA, heavy metals in blood, vitamin D level, and nutritional intakes. The overall prevalence of anemia, ID and IDA was 12.4%, 23.11%, and 7.7%, respectively. ID and IDA were more prevalent among adolescents (aged 15-18 yr; 36.5% for ID; 10.7% for IDA) and women aged 19-49 yr (32.7% for ID; 11.3% for IDA). The proposed path model showed that IDA was associated with an elevated cadmium level after adjusting for age and body mass index (β=0.46, P<0.001). Vitamin D levels were found to affect IDA negatively (β=-0.002, P<0.001). This study shows that the prevalence of anemia, ID, and IDA are relatively high in late adolescents and women of reproductive age. Path analysis showed that depressed vitamin D levels increase the risk of IDA, and that IDA increases cadmium concentrations in blood. Our findings indicate that systematic health surveillance systems including educational campaigns and well-balanced nutrition are needed to control anemia, ID, and IDA.

Vitamin D Supplementation and Hemoglobin Levels in Hypertensive Patients: A Randomized Controlled Trial

Epidemiological evidence suggests that circulating 25-hydroxyvitamin D (25OHD) levels are inversely associated with hemoglobin (Hb) levels and anemia risk. We evaluated whether vitamin D supplementation improves Hb levels and reduces anemia risk in hypertensive patients. Two hundred patients with 25OHD levels <75 nmol/L who attended the Styrian Vitamin D Hypertension Trial were included, of whom 188 completed the trial. Patients randomly received 2800 IU vitamin D3 daily or a matching placebo for eight weeks. Initially, the prevalence of anemic status (Hb levels <12.5 g/dL) and deficient 25OHD levels (<30 nmol/L) was 6.5% and 7.5%, respectively. All anemic patients had 25OHD levels >50 nmol/L. The mean (95% confidence interval) vitamin D effect on Hb levels was 0.04 (-0.14 to 0.22) g/dL (P = 0.661). Moreover, vitamin D treatment did not influence anemic status significantly (P > 0.999). Likewise, vitamin D had no significant effect on Hb levels in the subgroups of anemic patients or in patients with initial 25OHD levels <30 nmol/L. In conclusion, a daily vitamin D supplement of 2800 IU for eight weeks did not improve Hb levels or anemic status in hypertensive patients. Future trials should focus on anemic patients with deficient 25OHD levels (e.g., <30 nmol/L). This trial is registered with clinicaltrials.gov [NCT02136771].

Vitamin D and anemia: insights into an emerging association

PURPOSE OF REVIEW

The current review highlights recent findings in the emerging association between vitamin D and anemia through discussion of mechanistic studies, epidemiologic studies, and clinical trials.

RECENT FINDINGS

Vitamin D has previously been found to be associated with anemia in various healthy and diseased populations. Recent studies indicate that the association may differ between race and ethnic groups and is likely specific to anemia of inflammation. The mechanism underlying this association involves the reduction of proinflammatory cytokines by vitamin D and the direct suppression of hepcidin mRNA transcription. There is also evidence that vitamin D may be protective against anemia by supporting erythropoiesis. Other calciotropic hormones including fibroblast growth factor 23, and parathyroid hormone have also been found to be associated with iron homeostasis and erythropoiesis.

SUMMARY

Recent advances in our understanding of the association between vitamin D and anemia suggest that maintenance of sufficient vitamin D status may be important in preventing anemia, particularly in diseases characterized by inflammation. Early clinical trials have been promising, but further research is needed to define the efficacy of vitamin D as a future approach for the treatment of anemia.

Vitamin D Status and the Risk of Anemia in Community-Dwelling Adults: Results from the National Health and Nutrition Examination Survey 2001-2006

Low vitamin D status has been implicated in several chronic medical conditions and unfavorable health outcomes. Our goal was to investigate whether serum 25-hydroxyvitamin D (25OHD) levels are a potentially modifiable risk factor for anemia in a nationally representative cohort of community-dwelling individuals in the United States. We performed a cross-sectional study of 5456 individuals (≥17 years) from the National Health and Nutrition Examination Survey from 2001 to 2006. Locally weighted scatterplot smoothing (LOWESS) was used to graphically depict the relationship between serum 25OHD levels and the cumulative frequency of anemia. Multivariable logistic regression models were then used to assess the independent association of 25OHD levels with anemia, while controlling for age, sex, race, body mass index, chronic kidney disease, as well as serum levels of C-reactive protein, ferritin, iron, vitamin B12, and folic acid. The mean (standard error) 25OHD and hemoglobin levels in the analytic group were 23.5 (0.4) ng/mL and 14.4 (0.1) g/dL, respectively. Prevalence of anemia was 3.9%. Locally weighted scatterplot smoothing analysis demonstrated a near-linear relationship between vitamin D status and cumulative frequency of anemia up to 25OHD levels of approximately 20  ng/mL. With increasing 25OHD levels, the curve flattened out progressively. Multivariable regression analysis demonstrated an inverse association of 25OHD levels with the risk of anemia (adjusted odds ratio 0.97; 95% confidence interval 0.95-0.99 per 1  ng/mL change in 25OHD). Compared to individuals with ≥20  ng/mL, individuals with 25OHD levels <20  ng/mL were more likely to be anemic (adjusted odds ratio 1.64; 95% confidence interval 1.08-2.49). In a nationally representative sample of community-dwelling individuals in the United States, low 25OHD levels were associated with increased risk of anemia. Randomized controlled trials are needed to determine whether optimizing vitamin D status can reduce the burden of anemia in the general population.