Oxidative stress is thought to have some role in etiology of depression . Lycopene is the most powerful antioxidant (100 times potent than vit E) amongst carotenoids. Tomatoes are the natural source of lycopene.Dietary intake of tomatoes/tomato products containing lycopene have been shown to be related to decreased risk of some chronic medical illnesses (De Pablo et al., 2007; Heber and Lu, 2002).One previous study has shown that antioxidants (Vit E) have preventive effect in depression among male elderly patients.(Shibata et al., 1999).
Would a tomato rich diet prevent depressive symptoms ?
Kaijun Niu et al investigated the relationship between a tomato- rich diet and depressive symptoms in a community-dwelling elderly (70 yrs or over) Japanese population.1169 participants completed the (Geriatric Depressive symptoms Scale:GDS). After excluding those with cognitive symptoms and cancer, 986 participants remained.Detailed information on food intake and physical health were collected.
20% had severe depressive symptoms.The mean GDS score was significantly lower across the tomatoes/tomato products groups (p for trend o0.0001). The proportion of male, current smoker, lower educational level, and widowed or divorced status were significantly lower across the tomatoes/tomato products groups . The proportion of subjects who were married was significantly higher across the tomatoes and tomato products groups . Mean total energy intake was significantly higher across the tomatoes/ tomato products groups. The relationship remained significant after the multiple confounding variables were taken in to account.
The study show that high intake of tomatoes/tomato products was independently related to a lower prevalence of depressive symptoms. No relationship was observed between intake of other kinds of vegetables and depressive symptoms.
Limitations: Lycopene concentration was not measured in this study.Frequency of eating tomatoes/tomato products was used to assess the relationship between tomatoes/lycopene and depressive symptoms in this study. This is a cross-sectional study showing an association.( ie not causation).The presence or degree of these chronic medical illnesses may be a potential mechanism linking intake of tomatoes and tomato products to depressive symptoms.
Prospective studies or interventional studies would add more light to this association.
Depression is a common disorder.Depressive symptoms are more common. Research in to diet and mood is a developing area.This study supports the idea that antioxidants might be helpful in keeping our mood steady.
Summary of the article:
A tomato-rich diet is related to depressive symptoms among an elderly population aged 70 years and over: a population-based, cross-sectional analysis.Niu K, Guo H, Kakizaki M, Cui Y, Ohmori-Matsuda K, Guan L, Hozawa A, Kuriyama S, Tsuboya T, Ohrui T, Furukawa K, Arai H, Tsuji I, Nagatomi R.J Affect Disord. 2013 Jan 10;144(1-2):165-70.