The aim of this study was to assess whether self-reported mental health status, measured using the SF-36 questionnaire, was associated with fish consumption, assessed using a food-frequency questionnaire.

The cross-national data were collected in the 1996/97 New Zealand Health Survey and 1997 Nutrition Survey, which were conducted using the same sampling frame. Survey respondents were categorised into those who consumed no fish of any kind and those who consumed some kind of fish, at any frequency. Data were adjusted for age, household income, eating patterns, alcohol use and smoking. Other demographic variables and potential confounding nutrients were included in the preliminary analyses but were not found to have a significant relationship with fish consumption.

Data from a nationally representative sample of 4644 New Zealand adults aged 15 years and over were used in this analysis.

Fish consumption was significantly associated with higher self-reported mental health status, even after adjustment for possible confounders. Differences between the mean scores for fish eaters and those who never eat fish were 8.2 for the Mental Health scale (P = 0.005) and 7.5 for the Mental Component score (P = 0.001). Conversely, the association between fish consumption and physical functioning was in the opposite direction (P = 0.045).

This is the first cross-sectional survey to demonstrate a significant relationship between fish intake and higher self-reported mental health status, therefore offering indirect support for the hypothesis that ω-3 polyunsaturated fatty acids may act as mood stabilisers.