The Effect of Serum 25-Hydroxyvitamin D on Serum Ferritin Concentrations: A Longitudinal Study of Participants of a Preventive Health Program.

Nutrients. 2019;11(3)

Plain language summary

Serum ferritin (SF) is the storage form of iron in the body. SF has been shown to increase as part of the body’s response to inflammation, and is therefore recognised as a marker of inflammation. Vitamin D has a key function in bone metabolism and is increasingly recognised for its anti-inflammatory effect. This longitudinal study looked at the association of serum 25-hydroxyvitamin D (25(OH)D) with levels of SF concentrations, and examined whether changes in serum 25(OH)D concentrations over time were accompanied by a change in SF concentrations. The study analysed data from 6812 Canadian adults who participated in a preventative health program. Just under half the participants were taking vitamin D supplements at a dose of 2000-5000iU per day. Measurements were taken at the start of the study, and at follow-up, which was an average of 12 months later. 25(OH)D levels at baseline were grouped into categories: <50nmol/L, 50 to <75nmol/L, 75 to <100nmol/L, 100 to <125nmol/L and >125nmol/L. During the follow-up, 25(OH)D concentrations increased from 80.7 to 115.0 nmol/L whereas SF concentrations decreased from 122.0 to 92.0 µg/L. Compared to participants with very low 25(OH)D concentrations of <50 nmol/L, those with concentrations of 75 to <100, 100 to <125, and ≥125 nmol/L had SF levels that were 13.00, 23.15, and 27.59 µg/L lower respectively (p < 0.001). Participants who improved their 25(OH)D levels by ≥50 nmol/L over the study period, decreased their SF concentrations by an average of 5.71 µg/L. The authors concluded that interventions aiming to lower SF concentrations through sun-exposure and vitamin D supplementation should aim for increases in 25(OH)D concentrations of at least 50nmol/L. Intervention studies are needed to further establish the beneficial effects of vitamin D on inflammation and cardiovascular health.

Abstract

undefined: Various studies have suggested a role of vitamin D in inflammation. However, its effect on ferritin, a biomarker of inflammation, has received relatively little attention. Therefore, we aimed to assess the association of serum 25-hydroxyvitamin D (25(OH)D) with serum ferritin (SF) concentrations, and to examine whether temporal increases in serum 25(OH)D concentrations are paralleled by a reduction in SF concentrations. Data from a community sample of Canadian adults who participated in a preventive health program ( = 6812) were analyzed. During the follow-up, serum 25(OH)D concentrations increased from 80.7 to 115.0 nmol/L whereas SF concentrations decreased from 122.0 to 92.0 µg/L (median follow-up time was 11.67 months). Cross-sectional analyses revealed that compared to participants with 25(OH)D concentrations of <50 nmol/L, those with 25(OH)D concentrations of 75 to <100, 100 to <125, and ≥125 nmol/L had SF concentrations that were 13.00, 23.15, and 27.59 µg/L lower respectively ( < 0.001). Compared to those without temporal improvements in 25(OH)D concentrations between baseline and follow-up, participants who improved their 25(OH)D concentrations with ≥50 nmol/L decreased their SF concentrations with 5.71 µg/L. For participants for whom the increase in 25(OH)D concentrations was less than 50 nmol/L, decreases in SF concentrations were less pronounced and not statistically significant. These observations suggest that despite strong associations between 25(OH)D and SF concentrations, interventions aiming to lower SF concentrations through sun-exposure and vitamin D supplementation should target substantial increases in 25(OH)D concentrations.

Lifestyle medicine

Fundamental Clinical Imbalances : Immune and inflammation
Patient Centred Factors : Mediators/Vitamin D
Environmental Inputs : Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood
Bioactive Substances : Ferritin ; Vitamin D ; Calcidiol

Methodological quality

Allocation concealment : Not applicable
Publication Type : Journal Article

Metadata

Nutrition Evidence keywords : Iron ; Ferritin ; Calcidiol ; Anti-inflammatory