Dr Amanda Patterson: Iron deficiency in women of childbearing age.
The current prevalence of iron deficiency for Australian women of childbearing age is unknown, but baseline data from the Australian Longitudinal Study of Women's Health (ALSWH) suggest that one in three women have had diagnosed iron deficiency by the age of 45-50 years. Despite this, dietary and lifestyle factors which are important in the development of iron deficiency have not yet been clearly defined for Australian women, and the public health impact of this condition remains unclear. In addition, while the Australian Iron Status Advisory Panel (AISAP) currently recommends dietary intervention as the first line of treatment for iron deficiency in adults, the efficacy of dietary treatment has not been evaluated. The thesis resulting from this PhD research describes a series of studies which examine the development, implications and treatment of iron deficiency for Australian women of childbearing age. A detailed literature review provides background information on the physiology of iron, the biochemical and haematological variables used to assess iron status, and the current definitions used for the diagnosis of iron deficiency. Iron deficiency has been shown to adversely affect work performance, immunity, thermoregulation and cognitive functioning, and the research describing these relationships is reviewed. Dietary and lifestyle factors thought to be important determinants of iron status, and the current strategies used in the prevention and treatment of iron deficiency are also discussed.
The PhD work included two preliminary studies. The first was a general practitioner (GP) survey and pathology audit which examined the knowledge, attitude and behaviour of GPs in relation to the diagnosis and treatment of iron deficiency. While diagnosis practices were generally in accordance with AISAP recommendations, treatment practices were not. Supplementation was the preferred treatment option in even mild cases of iron deficiency, and this preference may reflect the poor dietary knowledge of GPs in relation to enhancers and inhibitors of iron absorption. The second preliminary study was an epidemiological analysis of baseline and follow-up data from the ALSWH to determine the impact of self-reported iron deficiency on general health and well-being (measured using the Short Form-36 General Health and Well-being questionnaire; SF-36) for two large cohorts of Australian women. Baseline and longitudinal analysis of these data showed reduced vitality and physical and mental health for women who reported iron deficiency. The major component of this research was a randomised control trial which compared dietary and supplement treatment for iron deficiency. Baseline dietary, lifestyle and morbidity data were examined for iron deficient and iron replete women. Multivariate analyses were used to investigate the relative importance of dietary and lifestyle factors in the development of iron deficiency for women of childbearing age. Iron status was positively associated with oral contraceptive pill use and alcohol consumption and negatively associated with phytate intake.
The effects of iron deficiency on general health and well-being, fatigue and cognitive functioning were examined using the SF-36 general health questionnaire, the Piper Fatigue Scale and four sub-scales of Wechsler Adult Intelligence Scale-Revised (WAIS-R), respectively. Iron deficiency was associated with decreased mental health, vitality and cognitive functioning, and increased fatigue in the baseline data. Dietary and supplement treatment for iron deficiency and the relative effects of each on general health and well-being, fatigue and cognitive functioning were compared. Both dietary and supplement treatment resulted in significant improvements in haemoglobin and serum ferritin, but changes in serum ferritin were seen more quickly for the supplement group. Women in both the diet and the supplement intervention groups showed significant improvements in general health and well-being, fatigue and cognitive functioning during the trial.
Improvements in mental health were more marked among women in the diet intervention group, while vitality and fatigue improved similarly for women in both groups. Women in both groups also improved similarly on two sub-scales of the WAIS-R which assess reasoning and perceptual organisation. From this research it is clear that women who suffer from iron deficiency experience major morbidity in terms of vitality, fatigue and general health and well-being. Dietary intakes of alcohol and phytate have been highlighted as possible factors in the determination of iron status, and dietary treatment of iron deficiency has been shown to be effective