The present study as the first study in world aimed to assess the association of PPD and postpartum hypochondriasis with intake of micronutrients in each trimester. The results showed that intake of iron, selenium, iodine, folate, vitamin C, B12, EPA in all trimesters and vitamin c in second trimester was significantly lower in women with PPD rather than women without that.
Iron as the main component of hemoglobin of red blood cells is responsible for transporting oxygen. Iron deficiency induces anemia and results in insufficient oxygen delivery to cells [26, 27]. Also, Iron deficiency anemia with decline of hemoglobin concentration increased significantly risk of depression in an independent dose pattern among old population; as, the lower the level of hemoglobin the worse the severity of depression [28]. Further studies in future are needed to determine the optimal and safe dose of iron supplements for depressive pregnant women.
Regarding selenium, recent studies showed depression symptoms in patients with low level of serum selenium that were treated and improved with selenium supplements [29]. Another study showed that selenium supplements during pregnancy declined depression (based on score of Edinburg questionnaire) in 8 weeks post-partum [30]. It is unknown the mechanism of impact of selenium on mood. Selenium is necessary for synthesis and metabolism of thyroid hormones. Little changes in function of thyroid are associated with depression [31]. Selenium deficiency causes thyroid hormone dysfunction that may mediates impact of selenium on depression [31]. Selenium is a main component of antioxidant enzyme glutathione peroxidase that is involved in antioxidant mechanisms and protects nerves of damages and lipoperoxidation [19]. Based on a randomized clinical trial in patients with HIV, the researchers reported that selenium supplement improved depressive mood and quality of life score 20 times [32]. Also, selenium supplement (100–150 microgram per day) for 5–6 weeks improved depressed–dejected mood state and a trend toward improvement in quality of life scores [32] .
Interaction between selenium and iodine in synthesis of thyroid hormones is a significant concern in Iran due to selenium and iodine sufficiency. Iodine sufficiency is a health problem in Iran. After performing the mandatory fortification program in 1991, many children and adults have optimal iodine intake [33]. Unfortunately, the present study showed that insufficient intake and iodine deficiency continues in pregnant women despite implement of mandatory iodine fortification. Selenium deficiency could worsen the consequences of iodine deficiency among this vulnerable group [34]. Iodine is a trace element that is an essential component of thyroid hormones It was shown that hypothyroidism is associated with mood disorders [35, 36], cognitive and affective disturbances [37] and memory impairment [38]. Also the relationship between depression and subliclinical hypothyroidism in animal model was investigated [39].
The present study showed that insufficient intake of some antioxidants is associated with PPD. Antioxidants (vitamin C/ B12, Folate) could be protective as a defense mechanism against PPD [40]. Antioxidants (vitamin C/ B12, Folate) could be protective as a defense mechanism against brain/vascular damages of oxidative stress related to reactive oxygen species (ROS) [40]. Folate and vitamin B12 have fundamental roles in normal function of central nervous system and could regulate mood through some mechanisms [40]. For example, they are essential for some metabolic process in CNS such as methylation and construction of serotonin and other neurotransmitters, neuroamines, and catecholamines [41, 42]. Also, metabolism of hemosystein depends on sufficient levels of folate and vitamin B12 and the level of hemosystein is a sensitive indicator of deficiency of folate and vitamin B12 [43]. Based on some studies, level of hemosystein is higher and level of vitamin B12 and folate is lower in depressive patients [44]. Higher level of hemosystein could induce a vascular response resulting in depression [45]. A recent meta-analysis showed that folate deficiency is associated with a 55% increased risk of depression disregarding folic acid fortification or method of assessment of folate intake (questionnaire/serum folate measurement) [46]. Also, it was determined that the patients with lower level of folate had weaker response to antidepressants [47, 48]. Several studies indicated improvement of depression symptoms after adding folic acid to antidepressants [49–52]. Previous studies reported that high intake of vitamin B12, selenium, and magnesium was associated with lower depression syndromes in pregnant and non-pregnant women [30, 53–57].
Eicosapentanoic acid (EPA), one of n-3 PUFAs is significant for psychological health. It is mainly/mostly in fish and other sea foods [19]. EPA is a main constructive component of phospholipid membrane and is incorporated into cell membranes in whole body. It determines the biophysical characteristics of membrane of neurons[58]. Fatty acids affect receptors functions, neurotransmitters uptake, and signal transport. Association between EPA, inflammation and vascular disease may have a role in pathogenesis of depression because depression is associated with inflammation and atherosclerosis [59–61]. EPA is a precursor of some prostaglandins and Leukotrienes that are strong vasodilators and inhibitors of platelets aggregation and could decline the risk of vascular diseases [62]. Considering that docosehexaenoic acid (DHA) is essential for normal function of brain and EPA is a significant factor to inhibit inflammation process, a hypothesis poses that increase of fat acids N3 results in improvement of PPD. 1 g/d of EPA has been shown to be an effective adjuvant to antidepressant therapy in resistant depressed patients [63–65]. Peet and Horrobin (2002) determined that addition of low-dose EPA to standard antidepressant therapy in depressed patients achieved a 50% improvement compared to a paraffin placebo with minimal side effects[63]. Therefore, addition of EPA supplementation may be beneficial for the 30–50% of patients resistant to standard depression treatment.
This study indicated that level of iron, iodine, folate, selenium, EPA was lower in hypochondriac participants. Unfortunately, there is no similar study to be compared with the findings of present study. Considering that depression and hypochondriac have significant association [7], deficiency of micronutrients related to hypochondriac or depression could aggravate each other. The present study has some strong points including population-based design, large sample size, and little drop-out rate (only 5 participants) that could prevent selection bias. Also, the study was conducted in whole rural areas of the Hormozgan province and was not limited to some special areas; since, depression and especially nutrition are associated with various factors such as socioeconomic status, education level, and culture that all of them could be influenced by the place of residence (rural or urban). Conducting the study in whole rural areas of the province prevented selection bias and yield a more precise assessment of association of nutrition, PPD and hypochondriasis. Moreover, in this study, potential confounding factors were controlled. For example, nutrition questionnaire was completed in each trimester (not after birth); so, the findings could not be influenced by appetite in various periods of pregnancy. Another strong point was using validated FFQ to assess nutritional status; since, it is a standard tool for assessing long-term nutritional status in cohort and cross-sectional studies. The limitation of present study was applying self-reported questionnaires for post-partum depression (Edinburg) and hypochondriasis. However, both questionnaires are used for screening as valid tools [66, 67].