Depression is a global public health problem that is listed as the second most serious health problem worldwide, following cardiovascular disease, it approximately effect >300 million individuals around the world, according to the World Health Organization (WHO) (Lancet (London, England), 2018). The global prevalence of major depressive disorder has considerably increased by 27.6 % in 2020 as a result of the COVID-19 pandemic (Lancet Psychiatry, 2020; Lancet (London, England), 2021).

The pathophysiology of depression was thought to be influenced by neurological, psychological, social, and hereditary variables (Raison et al., 2006). For instance, age, sex, race, family history of mood disorders, and chronic illness have been linked to the risk of depression (Sullivan et al., 2000; Kessler et al., 2003). Although the exact pathophysiology of depression is unknown, dietary differences across individuals have a substantial impact on the onset and progression of depression. Currently, increasing research evidence has suggested the relationship between dietary and depression, high amounts of non-refined grains, fruits, vegetables, whole-grain, legumes, and nuts were inversely related to depression (Gibson-Smith et al., 2020; Grases et al., 2019).

SPD is a natural polyamine present in all living organisms. Food items with high SPD content is present durian fruit, soybean, apple, banana and avocado and foods that have been fermented with bacteria and fungi, including natto or a variety of mature cheeses, the veal, beef, chicken, milk and egg are also enriched with SPD (Muñoz-Esparza et al., 2019; Kalač, 2014). Because these foods intake are associated with depression, and these foods are rich in SPD, it is speculated that SPD is closely related to depression.

Previous studies in both people and animals shown higher intake of SPD association with better overall health and mental disorders (Madeo et al., 2018; Pekar et al., 2021; Wirth et al., 2018). Few studies have investigated specifically the connection between dietary SPD and depression. As a result, this research aims to investigate the association between dietary SPD and depression in a cohort of American individuals who were not hospitalized. We proposed a hypothesis that a larger intake of SPD in the diet is associated with increased depression.