Association between depression and fruit and vegetable consumption among adults in South Asia
Depression represents a major public health concern worldwide and it is often referred as the common cold in the field of psychiatry. This analogy may provide a good understanding of the frequency of occurrence, however its significance goes far deeper with repercussions on academic and professional performance, Quality of Life (QoL), familial and Social Well Being (SWB). Global Burden of Disease (GBD) 2010 Study reported a global prevalence of Major Depressive Disorder (MDD) of 4.7% (4.4–5.0%) with an incidence of 3.0% (2.4–3.8%) [1]. Moussavi et al. reported a lifetime prevalence of depression of 15 to 20% globally [2]. Another Global Burden of Disease (GBD) 2010 study reported that MDD ranked 11th among the leading causes of Disability Adjusted Life Years (DALYs) worldwide in 2010, a 37% increase since 1990 (15th in 1990) [3]. Worldwide, about 25% of individuals develop one or more mental or behavioral disorders during their lifetime [4]. In 2002, depression was the third leading cause of disease burden (equivalent to 4.3% of all DALYs), and also the leading cause of disability responsible for 13.4% of Years Lived with Disability (YLDs) in women and 8.3% in men [5]. According to the World Health Organization, depression is projected to be a leading cause of disability worldwide by 2020, second only to ischemic health disease [6].
There is a growing volume of research dedicated to investigating the epidemiology and rising prevalence of depression, the risk factors, and devising preventive and intervention measures. Some have attributed the increasing prevalence to the changing lifestyle brought by modernity and to the depressiogenic/stressogenic environment it has brought along e.g. dietary changes, urbanization, social inequality and isolation, loneliness, sedentary lifestyle, sleep-deprivation [7–9]. Certain lifestyle related issues and adoption of unhealthy behaviours function as contributing factors to poor physical health outcomes and give rise to higher incidence of psychological disorders [7–10]. Pharmacological treatments of depressive disorders have experienced remarkable progress over the course of past 4–5 decades and constitutes to be the main therapeutic approach for depression. However, non-pharmacological management (e.g. dietary behaviour, physical activity) of psychological disorders are also gaining increasing attention. For instance, there has been a renewed interest in the potential role of dietary management such as fruit and vegetables consumption in preventing Non-communicable Chronic Disease (NCDs) including mental illnesses [11, 12]. According to some estimates, inadequate fruit consumption is the most prominent dietary risk factor for global disease burden and responsible for about 4.9 million (95% CI 3.8–5.9) deaths and 4.2% (95% CI 3.3–5.0) of global DALYs [13].
Fruits and vegetables are regarded as essential components of a healthy diet for their low energy content and rich sources of micronutrients, fiber, and other large number of bioactive compounds with potential effect on brain and overall health [14]. One widely accepted mechanism for higher fruits and vegetables consumption on better mental health is that antioxidants defend against the negative effects of oxidative stress, which is associated with depression [15, 16]. Moreover, antioxidants are shown to have beneficial effects on inflammatory markers which are associated with elevated levels of depression [17]. Regular consumption of fruits and vegetables can help body fight against the causative agents and cope up with depressive syndromes. Dietary guidelines by WHO/FAO recommends a minimum of 5 servings (400 g) of FV/day that provides a reasonable amount of micronutrients which may contribute to favorable cardiometabolic outcomes [18]. However, in many Low and Middle-Income Counties (LMICs) the level of FV intake is far lower than this level. In South Asia for instance, FV intake among adults in India and Pakistan was reported at about 100 g per capita per day or less, compared to 300 g in Europe and the USA [19]. Country level data on FV consumption are not available, however different sources suggest that average number of vegetable servings on the days when vegetable was consumed were of 3–3.4 servings in Matlab, and 1.3-1.5 servings in Vadu, India [19]. A multi-country study reported 74% lower than recommended level of FV consumption among adult population in India [20]. Though several researches have provided evidence on the role of FV consumption in the prevention of chronic diseases on South Asian population, there is no study so far conducted in the context of psychological disorders. With an aim to address this gap, we conducted this study exploring the association between the frequency of FV consumption and Self-Reported Depression. It should be noted that data on dietary pattern and mental illness are very limited in this region. We utilised datasets from the World Health Survey (2002–04) which is the first to provide country representative data on these indicators in South Asia.