Selenium intake and status of postpartum women and postnatal depression during the first year after childbirth in New Zealand – Mother and Infant Nutrition Investigation (MINI) study
Introduction
Selenium (Se) is essential in human health because selenoproteins play antioxidant and anti-inflammatory roles, and contribute to optimal levels of thyroid hormones [1]. Iodothyronine deiodinases are required for conversion of the inactive form of thyroid hormone (thyroxine, T4) to the active form (triiodothyronine, T3) [2]. Selenium as a component of the selenocysteine-containing proteins, glutathione peroxidase (GPx), protects the thyroid from oxidative damage [3]. Extremely low selenium intake has been associated with Keshan disease [4]. Selenium is thought to play a key role in optimal brain functioning [5]. Adequate dietary selenium intake has been found to improve mood among the general population, while low selenium intake is associated with low mood and an increased risk of de novo major depressive disorder in women [6,7]. This suggests that pregnant and postpartum women with low selenium intake may more at risk of experiencing postnatal depression, which affects 13 % of postpartum women globally [8].
In New Zealand, low levels of selenium in the food supply, and low selenium intakes have been reported in women of childbearing age [9] and postmenopausal women [10]. Low plasma selenium concentration among postpartum women and their infants resident in South Island of New Zealand (1998–1999) suggest inadequate status [11]. More recently, inadequate dietary selenium intake was reported in breastfeeding women three months after birth; however, selenium status from blood was not measured [12]. There are no current data describing selenium status among breastfeeding women in New Zealand. Given changes in dietary habits, food product availability and agricultural practices, continual monitoring of both selenium intake and status in this vulnerable postpartum population is essential. This study aims to investigate maternal and infant selenium intake and status during the first year postpartum. Furthermore, the relationship between selenium status and postnatal depression and anxiety will be investigated.
Section snippets
Study population
The Mother and Infant Nutrition Investigation (MINI) study is an observational longitudinal cohort study spanning the first year postpartum. Healthy breastfeeding women were recruited, in the Manawatu region, New Zealand, from June 2016 to December 2017. Women aged 16 years and older, who had given birth to a healthy term singleton infant aged less than three months were invited to join the study. Women were excluded: (1) if they developed significant health problems, such as metabolic disease
Results
In total, 87 breastfeeding women were recruited at three months postpartum, and most were followed up at six months (n = 78) and twelve months (n = 71). The mean age was 32 years, and 83 % were exclusively breastfeeding at three months after birth (Table 1). Most participants were Caucasian and achieved tertiary education. The majority had a vaginal delivery (78 %) and 44 % were delivering their first infant. In addition, 23 women reported that they had been smoking but most stopped for this
Sufficiency and deficiency
Suboptimal levels of dietary selenium intake were observed in our study participants. Maternal estimated selenium intake from the 4DDD was higher than previously reported from breastfeeding women (51 μg/day) from Palmerston North in 2009 and 2011 [12], and from Dunedin (South Island) between 2012 and 2013 [29]. The increase could be due to different dietary methods used in these studies. Weighed food records are suggested to be most precise dietary method in measuring usual nutrient intakes of
Conflict of interest
The authors declare no conflict of interest.
Funding
This work was supported by the Massey University Research Fund [no number, 2018], School of Food and Advanced Technology Postgraduate Fund [no number, 2016], and Oakley Mental Health Fund [no number, 2017]. The funding bodies played no role in the design of the study and collection, analysis, and interpretation of data or in the writing of the manuscript.
CRediT authorship contribution statement
Ying Jin: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Visualization, Writing - original draft, Writing - review & editing. Jane Coad: Conceptualization, Methodology, Funding acquisition, Supervision, Writing - review & editing. Rachael Pond: Resources, Writing - review & editing, Funding acquisition. Nick Kim: Resources, Writing - review & editing, Funding acquisition. Louise Brough: Conceptualization, Methodology, Funding acquisition, Formal analysis,
Acknowledgements
We thank the MINI team, including Ms. Anne Broomfield for her technical support and Ms. Rose Allen for her expertise in postnatal depression area. We would like to thank the women and their infants who volunteered for this study.
References (55)
Selenium and human health
Lancet
(2012)- et al.
Dietary selenium and major depression: a nested case-control study
Complement. Ther. Med.
(2012) - et al.
Dietary and biochemical selenium status of urban 6- to 24-month-old South Island New Zealand children and their postpartum mothers
J. Nutr.
(2004) - et al.
Using the Edinburgh postnatal depression scale to screen for anxiety disorders: conceptual and methodological considerations
J. Affect. Disord.
(2013) - et al.
Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial
Am. J. Clin. Nutr.
(2010) - et al.
Dietary selenium intake and selenium concentrations of plasma, erythrocytes, and breast milk in pregnant and postpartum lactating and nonlactating women
Am. J. Clin. Nutr.
(1987) - et al.
An evaluation of urinary measures of iodine and selenium status
J. Trace Elem. Med. Biol.
(1996) - et al.
Measurement and estimation of glomerular filtration rate in children
Adv. Chronic Kidney Dis.
(2017) - et al.
How much does low socioeconomic status increase the risk of prenatal and postpartum depressive symptoms in first-time mothers?
Women’s Heal. Issues.
(2010) - et al.
Optimal serum selenium concentrations are associated with lower depressive symptoms and negative mood among young adults 1 – 3
J. Nutr.
(2015)