Across the world, the number of hungry people is still unacceptably high, and approximately 800 million people do not eat enough food to live and an active and healthy life [1
]. Therefore, food insecurity (i.e., uncertainty of having, or inability to acquire, enough food because of insufficient money or other resources) is considered an ongoing public health issue in both developed and developing countries [2
]. The majority of hungry people live in developing countries, and 12.9% of the people in these regions remain chronically undernourished [1
]. Despite remarkable economic development, the prevalence of food insecurity was as high as 14.3% among Americans in 2013 [4
]. In Korea, a recent study using data from The Fifth Korea National Health and Nutrition Examination Survey (KNHANES V-3, 2012, Korea Centers for Disease Control and Prevention) reported that the prevalence of food insecurity was 11.3% among Korean adults [5
Many studies have reported the associations between food insecurity and unfavorable health outcomes [5
]. Food insecurity can cause malnutrition due to inadequate nutrient intake [5
]. In addition, food insecurity is related to various chronic diseases, such as obesity [7
], diabetes [8
], hypertension [8
], asthma [10
], and cancer [11
]. However, most studies have focused on socioeconomically vulnerable groups, such as children or low-income populations [6
]. Therefore, an analysis of nationwide data is needed for a comprehensive understanding of how food insecurity has contributed to chronic diseases.
Recently, it has been proposed that food insecurity is related to mental health problems such as mood disorders and depressive symptoms [12
]. Moreover, food insecurity was significantly more prevalent in adults with mood disorders compared to those without mood disorders (7.3% in the general population vs. 36.1% in those with mood disorders, p
< 0.001) [12
], and a dose–response relationship between food insecurity and depressive symptoms existed (odds ratio (OR) = 3.42, 95% confidence interval (CI): 2.61–4.49) [13
]. The Veterans Aging Cohort Study, which was performed on human immunodeficiency virus (HIV)-infected and uninfected veterans, conducted in 8 regions of the United States of America (Atlanta, Georgia; Baltimore, Maryland; Bronx, New York; Manhattan/Brooklyn, New York; Houston, Texas; Los Angeles, California; Pittsburgh, Pennsylvania; and Washington, District of Columbia) demonstrated that food insecurity was associated with poor medical health, with increases in reported conditions such as depression (OR = 3.00, 95% CI: 2.60–3.46) [14
]. Furthermore, food insecurity was also associated with mental health status in children, adolescents and individuals with the human immunodeficiency virus [15
]. A longitudinal study also suggested that food insecurity affected cognitive performance in elementary students [15
]. Even though food insecurity has emerged as a contributing factor for mental health status, there is limited information regarding the relationship between food insecurity and mental health status in Korean adults. In addition to these mental health associations, several previous studies have demonstrated the relationship between food insecurity and poor quality of life (QOL) in women and ethnic minority patients with cancer [18
]. Since it is a highly competitive society, Korea has a high rate of suicide and depression symptoms [20
]. Therefore, the identification of contributing factors associated with mental health status and QOL is needed to relieve the mental health problems and improve the QOL of Koreans. Consequently, we used representative data from a nationwide survey to investigate whether food insecurity is associated with inadequate nutrient intake, and if it negatively affects the mental health indicators and QOL of young and middle-aged Koreans.
This study was designed to determine the effect of food insecurity on nutrient intake, mental health indicators, and quality of life. The results of this study show that food insecure participants were nutritionally deficient and showed adverse mental health status and lower quality of life. Our results are consistent with earlier findings that reported a dose–response relationship between depression and food security: the OR of depression was higher in the lowest food-secure group than the highest food-secure group (OR = 3.42, 95% CI: 2.61–4.49) [13
]; and the food insecurity co-occurred with maternal depression (OR = 2.82, 95% CI: 1.62–4.93) [40
] assessed by DSM-IV tool. Also, other previous studies revealed that food insecurity status change was positively associated with less depression (estimates: 0.84), assessed by composite international diagnostic interview (CIDI) [19
], and demonstrated that there was strong association between food insecurity and psychological distress, assessed by the Kessler psychological distress scale (K-10) (OR = 3.4, 95% CI: 3.1–3.7) [41
]. We observed that food-insecure young and middle-aged participants showed significantly higher ORs for perceived stress, depression symptoms, and suicidal ideation. A previous cross-sectional study reported an association between food insecurity and psychological distress in healthy men and women [40
] and that food-insecure respondents experienced higher psychological distress compared to food-secure respondents in a clinical study on inpatients in a psychiatric hospital [42
]. In line with this, low-income adults showed dose–response relationships between the level of food insecurity and the prevalence of depressive symptoms [13
]. Additionally, a study using two longitudinal data sets demonstrated the relationships between food insecurity and depression in elderly adults [43
]. Moreover, a cross-sectional survey on mothers of 3-year-old children found a relationship between food insecurity and anxiety disorders [40
]. Another cross-sectional survey showed that food insecurity was more prevalent in adults with mood disorders than those without mood disorders [12
]. Our study corroborated previous findings that food insecurity was associated with mental health indicators, even in healthy adults. Since significant associations between food insecurity and mental health indicators were maintained after adjustment for socioeconomic and lifestyle factors known to affect mental health indicators, the impact of food insecurity on mental health may be independent of these factors in this healthy population.
Food insecurity was also closely associated with lower QOL such as exercise ability and daily activity in the general population. There were relatively limited data on the relationships between food insecurity and QOL; however, an inverse association between food insecurity and QOL has been observed in women [19
]. Recent studies on cancer patients also revealed that self-reported physical, functional, social, emotional well-being scores, and QOL decreased with increased levels of food insecurity [44
]. The relationship between food insecurity and QOL is complicated, because QOL is composed of multilateral factors such as exercise ability, self-management, daily activities, pain/discomfort, and anxiety/depression. However, some previous studies suggested that food insecurity may affect some factors of QOL, like exercise ability and daily activity, through low-quality food intake, essential nutrient deficiencies, and poor nutritional status [45
]. In our study, we found that the “food-insecure household” groups, particularly the “food-insecure household with hunger” group generally showed higher proportions of energy and nutrient deficiencies when compared with the 2015 KDRIs. This significantly affects mental health indicators and lowers QOL more so than it does in the “food-secure household” group.
In line with this, previous studies have documented the relationship between food intake and functional disability such as dressing, bathing, eating, and other activities [44
]. Studies on elderly Koreans proposed that frequent consumption of dairy products, legumes, or soy products were inversely related with functional disability [45
]. Dietary patterns are also associated with activities of daily living (ADL) and instrumental ADL (IADL) disability [47
]. Evidence also exists for the harmful effects of food insecurity on nutrition status. Studies addressing Chinese elementary students and Brazil adolescents showed that food insecurity was closely related to malnutrition risk [6
]. In our study, the proportion of participants who met the dietary reference intake for most nutrients were significantly lower in the “food-insecure household” groups, particularly the “food-insecure household with hunger” group, than the “food-secure household” group. Therefore, insufficient nutrition induced by food insecurity may be partly linked to lower QOL. However, in our study, the associations between food-insecurity, mental health indicators, and QOL were not compared between disabled and nondisabled participants, because we did not distinguish these differences among the KNHANES data.
Our results imply that mental health indicators and QOL are associated with food insecurity and may be improved by resolving food insecurity problems. Considering that Korea has the highest suicide rate and poor mental health status among Organization for Economic Cooperation and Development countries [49
], active intervention by the Korean government is necessary to reduce the food insecurity problem and promote better mental health. Korea has several nutrition assistance programs such as the “NutriPlus Program”, “the healthy fruit basket project”, and “free meal service”, which are provided for vulnerable populations [51
]. Moreover, some previous studies reported the effectiveness of these programs for vulnerable Korean populations [51
]. In our study, participation in the nutrition assistance program did not modify the association between food insecurity, mental health, and QOL.
Our study had several limitations as well. First, this was a cross-sectional study; therefore, we cannot explain causal relationships. Second, there was a possibility of underestimating food insecurity if respondents were reluctant to answer openly to the food insecurity questionnaire. Third, the KNHANES excluded extremely food-insecure people, such as the institution-dwelling or homeless population, because it was difficult to recruit them. Fourth, the associations between food-insecurity, mental health indicators, and QOL were not compared between disabled and nondisabled participants, because we did not distinguish these differences among the KNHANES data. Finally, the questionnaire to assess mental-health problems has not been fully validated [28
], even though several previous studies have used this questionnaire [29
]. Despite these limitations, our results have important strengths when compared to previous studies’ findings. As far as we know, this is the first study demonstrating that food insecurity is a strong factor that results in adverse mental health and lower QOL in the general population of Korean adults. We analyzed a representative, large-scale data set composed of participants with homogeneous characteristics (i.e., young, middle-aged Koreans without chronic diseases). In addition, we considered various sociodemographic and health-related factors in our adjustment to minimize the possibility of confounding factors.
In conclusion, food insecurity was closely associated with insufficient nutrient intake, adverse mental health indicators, and lower QOL in young and middle-aged Korean adults. Our results provide the basic information for a health policy to prepare more effective programs to improve the mental health and QOL of individuals who have an insufficient diet.