Impact of obesity on biomarkers of iron and vitamin D status in children and adolescents: The risk of misinterpretation

Patterns of 25-Hydroxyvitamin D3, Calcium Status, and Anemia in the Saudi Population: A Cross-Sectional Study

BACKGROUND

Emerging evidence suggests an intricate relationship between vitamin D, Ca²⁺, and inflammation-driven anemia. We, thus, investigated the patterns of serum 25(OH)D₃, Ca²⁺, ferritin, and iron in healthy and anemic members of the Saudi population.

METHODS

A population-based, retrospective, cross-sectional study was designed to analyze data for 14,229 subjects, aged 3-110 years, obtained from Al-Borg Medical Laboratories, over a six-year period (2014-2020). Gender and age differences were analyzed for 25(OH)D₃, Ca²⁺, hemoglobin, ferritin, and iron.

RESULTS

Vitamin D deficiency was extremely prevalent (98.47%) irrespective of age or gender, despite an increasing trend with age, in clear contrast to serum Ca²⁺. Ferritin was significantly lower in young adult and adult females, compared to elderly females, whereas iron was significantly reduced in females; in particular, adult females compared to young adults or elderly adults. Only anemic adult males had significantly lower 25(OH)D₃, while Ca²⁺ was consistently significantly diminished in anemics of all age groups, independent of gender. Notably, hypocalcemic subjects were 2.36 times more likely to be anemic. Moreover, ferritin, but not iron, was significantly diminished in anemics, which was only evident in young adults and adults. However, both ferritin and iron showed positive correlation with hematocrit, hemoglobin, MCH, MCHC, and MCV.

CONCLUSIONS

Despite being significantly lower in anemics, 25(OH)D₃ is not particularly associated with anemia, while hypocalcemia is associated with an increased risk for anemia. Assessment of vitamin D and Ca²⁺ status may be valuable in the clinical management of anemia in the Saudi population.

Dietary Approaches to Iron Deficiency Prevention in Childhood—A Critical Public Health Issue

Iron is an essential nutrient, and individual iron status is determined by the regulation of iron absorption, which is driven by iron requirements. Iron deficiency (ID) disproportionately affects infants, children, and adolescents, particularly those who live in areas with unfavorable socioeconomic conditions. The main reason for this is that diet provides insufficient bioavailable iron to meet their needs. The consequences of ID include poor immune function and response to vaccination, and moderate ID anemia is associated with depressed neurodevelopment and impaired cognitive and academic performances. The persistently high prevalence of ID worldwide leads to the need for effective measures of ID prevention. The main strategies include the dietary diversification of foods with more bioavailable iron and/or the use of iron-fortified staple foods such as formula or cereals. However, this strategy may be limited due to its cost, especially in low-income countries where biofortification is a promising approach. Another option is iron supplementation. In terms of health policy, the choice between mass and targeted ID prevention depends on local conditions. In any case, this remains a critical public health issue in many countries that must be taken into consideration, especially in children under 5 years of age.

Religious dietary rules and their potential nutritional and health consequences

BACKGROUND

The vast majority of the world population declares affiliation to a religion, predominantly Christianity and Islam. Many religions have special dietary rules, which may be more or less strictly adhered to.

METHODS

Religious food rules were collected from holy books and religious websites as well as their translation into dietary practices. The literature was searched for potential associations between these rules and potential nutritional consequences.

RESULTS

Jewish, Islamic and Indian religions support prolonged breastfeeding. Religious avoidance of alcohol is probably beneficial to health. When strictly applied, a few rules may lead to nutritional inadequacies, mainly in populations living in unfavourable socio-economic or environmental conditions. In Jewish and Muslim observants, animal slaughtering procedures may increase the risk of iron deficiency. Jews may be at risk of excess sodium intake related to home-prepared foods. A vegan diet, as observed by some believers, often by drifting from original precepts, or by some Hindus or Buddhists, may result in vitamin B12, calcium, iron, zinc, selenium and n-3 fatty acids deficiencies.

CONCLUSION

When implemented in accordance with the rules, most religious food precepts are not detrimental to health, as suggested by the fact that they have more or less been followed for millennia. Nevertheless, some practices may lead to nutritional inadequacies, such as iron, calcium, vitamin D and vitamin B12 deficiencies. Patients with low socio-economic status, children and women of childbearing age are of particular risk of such deficiencies. Being aware of them should help health professionals to take an individualized approach to decide whether to supplement or not.

Relationship between Obesity and Iron Deficiency in Healthy Adolescents

The relationship between overweight/obesity (excess of weight [EW]) and iron deficiency (ID) is not well defined. Objective: To analyze the relationship between EW and ID in healthy adolescents, assessing the contribution of new diagnostic measures of iron status and erythropoietic activity. Method: A cross-sectional study was made of 405 healthy adolescents, 12-16 years of age. A total of 289 were normal weight (NW) and 116 were otherwise healthy EW. Epidemiological, socioeconomic, diet, BMI Z-score, CRP (C-reactive protein), hematological, iron status, and erythropoietic activity parameters were measured. Statistical tests were Student's, analysis of variance (ANOVA), Chi-square, Pearson's correlation, and odds ratio. Results: ID prevalence in the EW group was 22.6% vs. 29.5% in the NW group (p: 0.3). Greater body weight was associated with lower reticulocyte hemoglobin content (CHr) (NW: 31.3 ± 1.7 pg vs. OW: 30.2 ± 1.7 pg, p: 0.007) and greater CRP (NW: 0.1 ± 0.2 mg/dL vs. OW: 0.2 ± 0.18 mg/dL, p < 0.001), leukocytes (NW: 6.69 ± 1.57 × 10³/L vs. OW: 7.43 ± 1.63 × 10³/L, p < 0.02), platelets (NW: 265.6 ± 58.9 × 10³/L vs. OW: 291.8 ± 54.4 × 10³/L, p < 0.002), ferritin (NW: 32.1 ± 17.9 ng/mL vs. OW: 42.8 ± 20.3 ng/mL, p: 0.01), serum transferrin receptor (sTfR) (NW: 1.39 ± 0.4 mg/L vs. OW: 1.73 ± 0.45 mg/L, p: 0.008), sTfR-F index (sTfR/log Ferritin) (NW: 1.06 ± 0.7 vs. OW: 1.33 ± 0.85, p: 0.036) and reticulocyte count (NW: 54.2 ± 18 × 10³/L vs. OW: 65.4 ± 24.2 × 10³/L, p: 0.003). A positive correlation was observed between the BMI Z-score and CRP, ferritin, sTfR, leukocytes, platelets, and reticulocyte count, and a negative one between the BMI Z-score and CHr and medium corpuscular volume. Conclusions: The prevalence of ID in otherwise healthy EW adolescents was no higher than in NW. The effect of obesity on iron status was low. The findings reveal the concomitant low-grade inflammation, and probably the effect of adiposity on erythropoietic activity. Specific cutoff values for ID in adolescents with OW need to be defined.

The Effect of Vitamin D Supplementation on Hepcidin, Iron Status, and Inflammation in Pregnant Women in the United Kingdom

Iron and vitamin D deficiencies are common during pregnancy. Our aim was to identify whether antenatal vitamin D₃ supplementation affects iron status (via hepcidin suppression) and/or inflammation. Using a subset of the UK multicenter Maternal Vitamin D Osteoporosis Study (MAVIDOS)-a double-blinded, randomized, placebo-controlled trial (ISRCTN82927713; EudraCT2007-001716-23)-we performed a secondary laboratory analysis. Women with blood samples from early and late pregnancy (vitamin D₃ (1000 IU/day from ~14 weeks gestation n = 93; placebo n = 102) who gave birth in the springtime (March⁻May) were selected as we anticipated seeing the greatest treatment group difference in change in 25-hydroxyvitamin D (25OHD) concentration. Outcomes were hepcidin, ferritin, C-reactive protein, and α1-acid glycoprotein concentration in late pregnancy (25OHD concentration was measured previously). By late pregnancy, 25OHD concentration increased by 17 nmol/L in the vitamin D₃ group and decreased by 11 nmol/L in the placebo group; hepcidin, ferritin, and inflammatory markers decreased but no treatment group differences were seen. In late pregnancy, positive relationships between 25OHD and hepcidin and 25OHD and ferritin in the placebo group were observed but not in the treatment group (group × 25OHD interaction, p < 0.02). Vitamin D₃ supplementation had no effect on hepcidin, ferritin, or inflammatory status suggesting no adjunctive value of vitamin D₃ in reducing rates of antenatal iron deficiency.