A Study to Investigate the Effect of Vitamin D3 Supplementation on Iron Status in Iron Deficient Women
Condition: Iron Deficiency; Anemia; Deficiency, Nutritional, With Poor Iron Absorption; Vitamin D Deficiency
MeSH terms: Anemia, Iron-Deficiency; Iron Deficiencies; Vitamin D Deficiency
Study type: Interventional

Summary: 
      Iron is one of the most vital elements in humans as it plays a role in physiological
      functions such as transferring and storing oxygen, transporting electrons and catalysing
      numerous reactions, from oxidative metabolism to cellular proliferation. Iron deficiency can
      be attributed to poor absorption that leads to insufficient iron to meet body requirements.
      Oral iron supplements have been extensively used to treat iron deficiency and iron deficiency
      anaemia. However, the use of iron compounds in fortifying foods is one of the best practical
      approach to combat iron deficiency, while improving diet and food pattern involves long-term
      goal which can be challenging. Vitamin D has recently been shown to affect hepcidin levels,
      which in turn has effects on iron status but there are a limited number of studies
      investigating the hepcidin profile in humans following iron supplementation, and few data are
      available, especially in humans, despite its role as a primary iron absorption and
      homeostasis regulator. Although several studies have been carried out using iron fortified
      products, there is limited data on the potential effect of vitamin D on iron metabolism
      amongst iron deficient women in particular. Therefore, the present study aims to investigate
      the effect of vitamin D3 supplementation (1500 IU) consumed with iron fortified breakfast
      cereals on haematological indicators and hepcidin response in iron deficient women.
    

Detailed description: 
      Recruitment And Sampling Strategy :

      Participants will be recruited within the University of Chester, UK only. Emails and
      posters/leaflets will be used as a medium of advertisement to the target group (staff and
      students). A total of 62 pre-menopausal women aged between 19 to 40 years old will be
      included in the study based on criteria described below. Eligibility will be based upon serum
      ferritin and also vitamin D concentrations at screening before the start of the study.
      Participants will be required to complete a screening questionnaire which will provide
      information about participant's health status, drugs/medication/supplement usage, and recent
      occurrences of illness/trauma/injury. A 6 ml venous blood will be drawn to assess
      concentrations of plasma ferritin vitamin D, haemoglobin and full blood counts, Participants
      with plasma ferritin concentrations below 20.0 µg/L and vitamin D concentration below 250
      nmol/l will be included in the study. If the levels of haemoglobin are found to be in severe
      stage of anaemia, the potential participant will be notified and advised to consult their
      General Practitioner (GP) (haemoglobin levels < 8.0 g/dL). All eligible participants will be
      briefed on the study protocol before the beginning of the study, and the eligible
      participants will be given a Participant Information Sheet (PIS) and asked to provide written
      informed consent.

      An 8 week, double blind, randomised controlled trial will be carried out in Chester, United
      Kingdom (UK). The 8 week intervention period was selected since more than 1 month is
      appropriate to generally enlarge the erythropoietic marrow and observe changes in red blood
      cell indices, especially in non-anaemic groups. Most vitamin D studies have used a supplement
      concentration of 1000 IU and reported no adverse effects in the participants. Some studies
      have used higher doses of 1600 or 4000 IU with no reported adverse outcomes in the
      participants.

      Participants will be randomly allocated to 2 groups:

        1. Fe group (iron fortified breakfast cereals and placebo)

        2. Vitamin D group (iron fortified breakfast cereals and vitamin D3).

      Each participant will consume 60 grams of iron fortified breakfast cereals containing a total
      of 9 mg of iron daily for 8 weeks with either vitamin D3 placebo or vitamin D3 (1500 IU)
      according to their assigned group. The participants will consume the iron fortified breakfast
      cereals in the morning, with 200 ml of semi-skimmed milk daily for a period of 8 weeks. The
      participants will consume the vitamin D or placebo in the evening with 200 ml of water.
      Participants will be asked to maintain their dietary habits and physical activity during the
      course of study. Participants will also be asked not to donate blood during the course of the
      study. The remaining supplements will be returned at the final clinic (week 8), and
      compliance will be estimated.

      Participants will be required to attend 3 clinics in total over a period of 8 weeks, and they
      will be assessed at baseline (Day 0), interim (Week 4) and post intervention (Week 8).
      Participants will be requested to fast overnight for approximately 8 hours before all
      clinics. At each clinic, a 30 ml blood sample will be taken and both height (cm) and weight
      (kg) will be measured. Before the start and the end of the study, participants will be
      required to keep a 3-day food diary which includes 2 weekdays and 1 weekend day to represent
      the habitual dietary intake of the participant. Blood samples will be batch analysed at the
      end of the intervention to assess all biomarkers of iron status and vitamin D metabolism.

      Sample size and justification :

      Sample size was estimated using iron supplementation data from a study carried out by
      Scholz-Ahrens et al. (2004) in which a serum ferritin concentration post intervention at 8
      weeks (mean ± S.D) of 17.7 ± 11.8 ug/l (Fe fortified milk group) and 10.6 ± 8.1 ug/l (non
      fortified milk group) was reported. With an effect size of 0.7015447, the total sample size
      required for each group in the proposed study is 26. Taking into account a 20% drop out rate,
      the total sample size required is 31 (Power = 0.80). Therefore, the total sample size needed
      for the whole study is 62. Sample size was estimated using of G Power Software Version 3.1.7.

      Statistical Analysis:

      All statistical analyses will be conducted with International Business Machines (IBM)
      Statistical Package for the Social Sciences (SPSS) Statistic Data Editor Software (Version
      21). Assuming that the data is normally distributed after performing a Shapiro Wilks
      normality test, one-way analysis of variance (ANOVA) with repeated measures will be conducted
      to compare the mean differences for all measured parameters within each group at baseline,
      interim and post intervention. The changes in the measured parameters between the periods of
      the study will be analysed using paired t-test. Pearson's correlation test will be performed
      to investigate the relationship between hepcidin profile and iron status biomarkers. A
      non-parametric approach will be adopted if the data is not normally distributed for all
      analyses. Differences will be considered significant with a p value ≤ 0.05.
    

Intervention name(s): Vitamin D3 supplement; Placebo
Intervention type(s): Dietary Supplement; Other
Intervention description(s): 1500 IU (37.5 mcg) Vitamin D3 capsules daily over 8 weeks (56 days); 65% olive oil capsules daily over 8 weeks (56 days)
Other intervention name(s): Cholecalciferol; Non active ingredient
Intervention MeSH terms: Vitamin D; Cholecalciferol
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: Iron deficiency; Vitamin D; Iron absorption; Hepcidin