Iron deficiency in young women : causes, consequences and solutions : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, New Zealand
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Date
2013
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Massey University
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Abstract
Background:
Iron deficiency is the most common nutritional deficiency worldwide and premenopausal
women are at particular risk. Iron deficiency without anaemia is associated with a number
of health consequences, including impaired work performance and possible impairments
to self-perceived health and well-being, and increased fatigue. Research into iron
deficiency and possible causes, consequences and solutions could help to improve the
quality of life for many premenopausal women.
Objectives:
This research aimed to investigate the causes, some of the consequences and a possible
solution to iron deficiency in premenopausal women. Objectives were to determine the
relative validity and reproducibility of an iron food frequency questionnaire (FeFFQ)
developed to identify iron-related dietary patterns; to identify the most important
determinants of suboptimal iron status and investigate the relative importance of dietary
patterns among these determinants; to determine the relationship between iron status and
self-perceived health, well-being and fatigue; and to investigate the effectiveness of a
dietary intervention using an iron-fortified breakfast cereal and milk consumed with either
high or low ascorbic acid, lutein and zeaxanthin-rich fruit to improve iron status in women
with low iron stores.
Method:
In a validation study, premenopausal women (n=115) completed the FeFFQ twice, one
month apart to assess reproducibility and a four-day weighed diet record (4DDR) to
assess validity. Dietary patterns from both FeFFQs and the 4DDR were identified using
factor analysis and agreement between diet pattern scores were compared using
correlation coefficients, Bland and Altman analysis, cross-classification and the weighted
κ- statistic. In a cross-sectional study, 375 premenopausal women completed the FeFFQ
(from which dietary patterns were identified) and a dietary practices questionnaire. They
also completed a health and demographic questionnaire including questions regarding
possible determinants of iron status, as well as a validated blood loss questionnaire. In a
second cross-sectional study, 233 female university students completed the SF-36v2
General Health Survey and Multidimensional Fatigue Symptom Inventory-Short Form
(MFSI-SF) questionnaire to investigate self-perceived health, well-being and fatigue. In
both cross-sectional studies, a blood sample was taken to determine iron status (serum
ferritin (SF), haemoglobin (Hb), C-reactive protein (CRP)). In a randomised controlled trial
(RCT), 69 women with low iron stores (SF≤25μg/L, Hb≥115g/L) received an iron-fortified
breakfast cereal (16 mg iron as ferrous sulphate) meal and either kiwifruit (intervention) or
banana (control) every day for 16 weeks. Iron status (SF, Hb, CRP, and soluble
transferrin receptor) was assessed at baseline and end.
Results:
Two dietary patterns (‘healthy’; ‘sandwich & drinks’) were identified from the FeFFQs and
4DDR. Correlation coefficients between the FeFFQ and 4DDR diet pattern scores
(validity) were 0.34 (‘healthy’), and 0.62 (‘sandwich & drinks’), both P<0.001. Correlation
coefficients between the two FeFFQs (reproducibility) were 0.76 for both dietary patterns
(P<0.001). Determinants of suboptimal iron status (SF<20μg/L) included blood donation
in the past year (odds ratio (OR) 6.7, [95% confidence interval (CI) 3.1, 14.7]; P<0.001),
being Asian (5.2 [2.4, 11.2]; P<0.001), having children (2.7 [1.4, 5.3]; P=0.003), previous
iron deficiency (2.1 [1.1, 3.9]; P=0.027), longer duration of menstrual period (1.3 [1.1, 1.6];
P=0.01), and following either a ‘milk & yoghurt’ (1.4 [1.1, 1.9]; P=0.014), or a ‘meat &
vegetable’ (0.6 [0.4, 0.8]; P=0.002) dietary pattern. Current iron status was not a
determinant of self-perceived health, well-being or fatigue after controlling for other
variables. In the RCT, iron status improved significantly (P<0.001) in the kiwifruit group
(SF from baseline to end (median [25th, 75th percentile]) (17.0 [10.5, 22.0]μg/L to 25.0
[20.0, 32.0]μg/L; P<0.001)) compared to the banana group (16.5 [10.0, 20.8]μg/L to 17.5
[12.3, 22.8)]μg/L; P=0.086).
Conclusions:
The FeFFQ was found to be a reproducible and reasonably valid tool for identifying ironrelated
dietary patterns. Following a ‘meat & vegetable’ dietary pattern reduced the risk,
while following a ‘milk & yoghurt’ dietary pattern increased the risk of suboptimal iron
status. The strongest predictors of suboptimal iron status were blood donation and Asian
ethnicity, followed by parity and previous iron deficiency. Both dietary patterns were
stronger predictors of suboptimal iron status than duration of menstrual period. Iron status
had no effect on self-perceived health, well-being or fatigue. Consumption of an ironfortified
breakfast cereal with kiwifruit compared to banana improved iron status in women
with low iron stores. Modification of dietary patterns and blood donation practices, as well
as the consumption of an iron-fortified breakfast cereal with an ascorbic acid, lutein,
zeaxanthin-rich fruit may contribute to improved iron status in women with low iron stores.
Description
Appendix 4 has been removed due to copyright restrictions:
Beck, K., Conlon, C., Kruger, R., Coad, J., Stonehouse, W. (2010), "The effect of gold kiwifruit
consumed with an iron fortified breakfast cereal meal on iron status in women with low iron
stores: a 16 week randomised controlled intervention study", BMC Public Health, 10:36
http://www.biomedcentral.com/1471-2458/10/36
Keywords
Iron deficiency in women, Nutrition in women, Iron in nutrition, Iron deficiency, Pre-menopausal women, Dietary requirements, Iron deficiency causes