Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers

ABSTRACT

The effectiveness of a morning versus evening oral iron supplement strategy to increase iron stores was explored. Ballet and contemporary dancers with serum ferritin (sFer) < 50μg/L (n = 14), were supplemented daily with 105 mg elemental oral iron in either the morning (Fe_AM) or evening (Fe_PM) for 8 weeks. A control group (n = 6) with sFer >50μg/L were given no supplement over the same period. Dancers’ sFer were measured at baseline and post-intervention. Assessment of daily training load, dietary intake, and menstruation were made. A significant interaction (p < 0.001) showed the within group sFer change over the 8-week intervention in Fe_AM (+25.9 ± 10.5μg/L) and Fe_PM, (+22.3 ± 13.6μg/L) was significantly different to CON (−30.17 ± 28.7μg/L; both p = 0.001). This change was not different between Fe_AM and Fe_PM (p = 0.778). sFer levels within Fe_AM and Fe_PM significantly increased over the 8-weeks; however, they significantly decreased in the CON group (all p < 0.05). Post-intervention sFer levels were no longer different between the three groups (p > 0.05). Training load, dietary intake, and number of menstrual cycles incurred were similar between Fe_AM and Fe_PM (p > 0.05). Oral iron supplementation in either the morning or evening appears equally effective in increasing sFer levels in dancers with sub-optimal iron status.

Highlights

• 8 weeks of oral iron supplements increases serum ferritin levels in elite dancers.

• Dancers not consuming an iron supplement showed a decline in serum ferritin over the 8-week period.

• Consuming the iron supplement in either the morning or the evening appeared equally effective in improving serum ferritin stores.

KEYWORDS:

• Iron supplement
• iron deficiency
• nutrition
• minerals

Acknowledgements

The authors would like to thank all dancers and their associated dance schools for their participation in this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Marc Sim is supported by a Royal Perth Hospital Research Foundation Fellowship (RPHRF CAF 00/21) and an Emerging Leader Fellowship from the Western Australian Future Health Research and Innovation Fund, Department of Health, WA.