The Association of Potato Consumption and Psychological Disorders in Women: A Cross-Sectional Study
 
Manije Darooghegi Mofrad; MSc¹, Fereydoun Siassi; PhD¹ , Bijan Guilani; PhD² & Leila Azadbakht; PhD^{*1, 3, 4
 
1}Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran.
² Department of Clinical Psychology, University of Tehran, Tehran, Iran.
³ Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
⁴ Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Science, Isfahan, Iran.
 

 
Introduction

ccording to the World Health Organization, the prevalence of mental disorders is increasing (Murphy et al., 2004). Mental disorders, like anxiety and depression are associated with heavy economic costs, disability, and early death (Olesen et al., 2012). Depression and anxiety with prevalence rate of 10-20% are the most common psychological disorders (Davis et al., 2003). Based on a meta-analysis, the prevalence of depression in Iran is about 25%. On average, mental disorders occur in Iranian women 1.95 times higher than men (Sadeghirad et al., 2010). The prevalence of anxiety was estimated at 15-35% in the general population (Kessler et al., 1994). Based on the epidemiological studies, the prevalence of the anxiety changed from 11.9% to 30.2% in Iran (Mohammadi et al., 2005).
The response rate of depressive persons to medical therapy was about 60-80%. In addition, 25% of the depressive patients received medication. Due to the poor reception of medical treatment and the possibility of the  disease recurrence, nutritional factors may have an important role in the prevention and treatment of depression (Penckofer et al., 2010). Several studies indicated the relationship between diet, depression, anxiety, and stress (Jacka et al., 2010). Studies reported that consumption of fruit, vegetables (Saghafian et al., 2018), and micronutrients such as vitamin C, B, D, E, and mineral such as calcium, potassium, magnesium, zinc, iron, and chromium as well as bioactive compounds such as phenolic compounds can reduce mental diseases (Kaplan et al., 2007).
Potato is known as one of the most popular foods all over the world. This starchy vegetable is a fundamental part of the most nation’s food supplies because of its fruitfulness properties and favorable taste (Zaheer and Akhtar, 2016). Traditionally, potatoes are identified as a vegetables; however, they are best classified as a refined starch because of their large amount of starch and unfavorable impact on the risk of diseases (Chiuve and Willett, 2007). Potato is a rich source of potassium and vitamin C; both play a role in reducing blood pressure (Camire et al., 2009). It also contains other minerals including magnesium, phosphorus, as well as dietary fiber (King and Slavin, 2013). Due to its high amounts of water, potato is considered as a food with low energy density (Anderson et al., 2013). However, high glycemic index and glycemic load of potato have caused some concerns about its growing consumption (Pagidipati and Gaziano, 2013). Several studies showed significant associations between potato consumption and risk of cardiovascular disease, diabetes, high blood pressure, obesity, and some cancers (Asli et al., 2017, Pietinen et al., 1996, Schwingshackl et al., 2018). However, potato consumption had no significant association with mortality (Darooghegi Mofrad et al., 2019, Osella et al., 2018).
In a cross-sectional study, Azadbakht et al. investigated 205 Iranian girls and found a significant relationship between potato consumption and obesity. However, potato consumption had no significant association with blood pressure (Heidari-Beni et al., 2015). In another study over 4774 Iranian women, potatoes were associated with an increased risk of diabetes. However, no relationship was observed between potato and other cardiovascular risk factors, such as high blood lipids and metabolic syndrome (Khosravi-Boroujeni et al., 2012). Another study conducted by Farhadnejad et al. demonstrated that potato consumption reduced the risk of diabetes in Iranian women (Farhadnejad et al., 2018).
According to our knowledge, no study has ever examined the relationship between potato consumption and mental disorders in the world. Due to the increasing prevalence of mental disorders in Iran, especially in women, the purpose of this study was to investigate the relationship of potato consumption with depression, anxiety, and stress in Iranian women.
Materials and Methods
Study design and participants: This cross-sectional study was conducted on 488 women who referred to the health centers affiliated to Tehran University of Medical Sciences. The participants were selected by multistage cluster sampling method in 2018. The health centers were randomly selected from 29 health centers in the south of Tehran. In each selected health center, we defined the number of required participants in proportion to the total number of persons attending the center. Women who were in the age range of 20-50 years old, Iranian, healthy, not pregnant and lactating, non-menopausal, not on any particular diet, and filled the consent forms entered the study. Furthermore, the participants were required to have no history of diabetes, cardiovascular, cancer, depression, lung, thyroid, kidney, liver, hypertension, multiple sclerosis (MS), and epilepsy disease and should not have the history of using anti-anxiety and anti-depressant drugs. The participants who did not complete the consent forms, did not cooperate in completing the questionnaires, and consumed less than 500 or more than 3500 kilo calorie of the energy were excluded from the study.
Assessment of dietary intake and potato consumption: Dietary intake was evaluated using a semi-quantitative food frequency questionnaire (FFQ) containing 168 food items that had already been validated (Esfahani et al., 2010). Potatoes in this questionnaire included boiled potato, fried potato, and potato chips. In dietary assessment, a subtitle should be devoted to potato consumption. Grilled, steamed, backed, and microvawed potatoes were not included in the questionnaire. Therefore, we did not consider these kinds of potato in our study. All questionnaires were completed by trained dietitians. Dietary behaviors on food preparation (especially in potato preparation) were asked from participants.
 Participants were asked to report the frequency of each food during the past year on a daily, weekly, monthly, and annually basis. The amount of each food was converted to gram using household measures. Later, the consumed gram of each food item was converted to daily intake. Each food item was coded and nutrients were analyzed using the NUTRITIONIST IV software for Iranian foods (version 7.0; N-Squared Computing, Salem, OR, USA).
Assessment of psychological profile: Psychiatric disorders were assessed using the Depression, Anxiety and Stress Scale (DASS-21), which reliability was previously confirmed (Samani and Joukar, 2007). To complete the questionnaire, one should identify the status of a symptom during the past week. Each of the three DASS subscales consists of 7 questions and its final score is obtained as the total score of the three subscales. The answers are divided into four categories of zero, low, medium, and high within the range of 0–3, respectively. Since the DASS-21 is the short-form of the original scale (42 questions), the final score achieved from each of these subscales should be doubled (Lovibond and Lovibond, 1995). Based on the total score, participants were ranked into five groups of normal, mild, moderate, severe, and very severe regarding their depression, anxiety, and stress status. However, due to the limited number of cases in some groups, they were divided into two groups of normal and mild/moderate/ severe/very severe. Depressive, anxiety, and stress symptoms were defined as score of equal or higher than 10, 8, and 15, respectively.
Assessment of other variables: General information was collected and recorded: age, marital status, socioeconomic status (home and welfare status), frequency of travels abroad, occupational status, education status, head of family educational status, number of family members, number of employed family members, number of children, head of family occupational status, number of deliveries, smoking, number of rooms, number of hours out of the home, satisfaction with the physical form, using supplementation or medication, adherence specific diet, having history of diabetes, cancer, cardiovascular, pulmonary, kidney, liver, high blood pressure, depression, thyroid, epilepsy, MS disease, and  family history of the mentioned disease.
The participants' height was measured in standing position without shoes by an inflexible meter to the nearest 0.5 cm. The participants' weight was measured by a digital scale (SECA, Hamburg, Germany) without shoes with a minimum of clothes and accuracy of 0.1 kg. Body mass index (BMI) was calculated by dividing the weight (kg) by height squared (m²). Physical activity was determined based on metabolic equivalents × h/d (Met.h/d) by recording physical activity over 24 hours. Moreover, the individuals' level of physical activity was calculated as Met.h/d (Ainsworth et al., 2000).
Data analysis: The variables' distributions were checked for normality using the Kolmogorov-Smirnov test. General characteristics across tertiles of potato intake were expressed as means ± SDs for continuous variables as well as numbers and percentages for the categorical variables. To examine the differences across tertiles, we used ANOVA for continuous variables and Chi-square test for categorical variables. Dietary intakes of study participants across tertiles of potatoes were compared using ANCOVA and all values were adjusted for energy intake. We used binary logistic regression to estimate ORs considering 95% CIs for psychological profile across tertiles of potatoes in crude and multivariable-adjusted models. In these analyses, age and total energy intake were controlled in the first model. Further adjustment was made for age, energy intake, socioeconomic status (low, medium and high), marital status (married, single), physical activity, supplement use (yes/no), drug use (yes/no), family history of chronic disease (yes/no), sleep time, out of home time, and body size image (normal, abnormal). In the final model, BMI was added to the adjustment. The P for trend was determined by considering tertiles of potatoes as ordinal variables in the logistic regression analysis. All statistical analyses were performed using the Statistical Package for Social Sciences (version 21; SPSS Inc.). in addition, P-value < 0.05 was considered to be statistically significant.
Ethical considerations: This study was approved by the Research Council and Ethics Committee of the School of Nutrition and Food Science, Tehran University of Medical Sciences, Tehran, Iran. All participants declared their willingness to participate in the study by providing written informed consent forms.
Results
In this study, 488 women aged 20-50 years with a mean age of 31.85 ± 7.67 years were included. The average BMI was 24.46 ± 4.10 kg / m². The prevalence of depression, anxiety, and psychological stress among participants was 34, 40, and 42%, respectively. In the third tertile of potato intake, women were younger than the first tertile. No significant difference was observed with regard to other demographic factors among potato intake tertiles. The distribution of demographic variables among potato tertiles can be seen in Table 1.
The average dietary intakes in each potato tertile showed that energy intake, thiamine, vitamin B6, and refined grains were significantly higher in the third terile than the first tertile of potato intake. In addition, consumption of the calcium, protein, vitamin C, fruit, dairy, sweet beverages, and red meat reduced significantly in the third tertile than the first tertile of potatoes. Dietary intakes of study participants across tertiles of potato are provided in Table 2.
Tables 3-5 show the odds ratio of depression, anxiety, and stress among potato tertiles. After adjustment of confounding variables, consuming potatoes had no significant association with depression (P = 0.12), anxiety (P = 0.19), and stress (P = 0.63). Furthermore, no significant association was found between eating boiled potatoes and depression (P = 0.59), anxiety (P = 0.19), and stress (P = 0.37).  Fried potatoes had no relationship with depression (P = 0.16), anxiety (P = 0.27), and stress (P = 0.97).

 Discussion