Depression in students is a major public health problem. Although several risk 
factors associated with depression have been identified, the cause of depression 
is still not clear. Several studies have demonstrated that physical activity and 
nutrient intake, such as increased levels of B vitamins in serum, decrease 
symptoms of depression. The aim of this study was to investigate the association 
between physical activity and dietary intake of vitamins B₆, B₉, and B₁₂ and 
symptoms of depression among postgraduate students. The results of this study 
suggest that intake of vitamin B9 may modulate the total score of Center for 
Epidemiological Studies Depression Scale (CES-D) and two subscales of the CES-D 
including depressive affect and interpersonal difficulties. This study also 
showed that moderate/high levels of physical activity were inversely and 
significantly associated with symptoms of depression (total scores) and three 
subscales of the CES-D including depressive affect, positive affect, and somatic 
complaints.