Likewise, an unhealthy dietary pattern observed in Australian women was associated with higher levels of depressive symptoms, but not men.
Researchers from Australia published their findings on the British Journal of Nutrition.
The study wanted to examine the association between current and past dietary patterns and depression in people aged 55 years and over, because previous studies had focused on the general adult population aged from 21 years, or older adults 65 years and over.
Researchers said: “These studies may have excluded the decade prior to age 65 when changes to depressive symptoms may be occurring,
“Understanding these associations is important as this knowledge can inform the development of evidence-based, appropriately timed dietary strategies to prevent poor mental health.”
In the current study, a total of 2142 participants completed the Wellbeing, Eating and Exercise for a Long Life study in Victoria, Australia.
Data from self-administered questionnaires were collected at three phases, T1 (2010), T2 (2012), and T3 (2014).
Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). A GDS score of 11 or greater may be an indicator of depression.
Dietary intake was assessed at T1 and T3 using a food frequency questionnaire over the previous six months.
Current diet and mental health
The findings suggested that a current healthy dietary pattern (characterised by frequent intake of vegetables, fruit and fish) was significantly associated (β = -0.260, 95% CI -0.451, -0.070) with lower levels of depressive symptoms in women.
A current unhealthy dietary pattern in women (characterised by frequent intake of red and processed meat, potatoes, hot chips, cakes, desserts and ice cream) was associated with higher levels of depressive symptoms (β = 1.367, 95% CI 0.679, 2.056).
In men, the healthy dietary pattern (characterised by frequent consumption of vegetables, fish and other seafood, oil and vinegar salad dressings, rice, legumes and beans, cottage or ricotta cheese and fruit saw a higher score for the association with lower levels of depressive symptoms, however the association was not significant.
The unhealthy dietary pattern (characterised by red, processed and cured meat, pizza or hamburgers, white bread, fried or battered fish, high energy drinks, hot chips or roast potatoes and muesli or porridge) was also not significantly associated with depressive symptoms.
Past diet and depression
The researchers also wanted to examine longitudinal associations of past dietary patterns at T1 and depressive symptoms at T3 (present).
In women, past healthy dietary patterns were associated with lower levels of depressive symptoms (β = -0.201, 95% CI -0.390, -0.013).
In men, no associations were found between dietary patterns and depressive symptoms.
The researchers said healthy dietary patterns in this study was similar to that of the Mediterranean diet in that vegetables, fruit, legumes, seafood are primary constituents of the diet.
Healthy dietary patterns have been associated with lower levels of inflammatory biomarkers including C-reactive protein and interleukin-6 indicating lower levels of inflammation.
Conversely, unhealthy dietary patterns have been linked to increased levels of the same inflammatory biomarkers indicating higher levels of inflammation.
Another explanation for why diet may be related to depressive symptoms may be related to fibre intake. A higher intake of dietary fibre has been associated with lower levels of the inflammatory biomarker C-reactive protein which may also decrease systemic inflammation.
No association in men
However, researchers were puzzled on why the association was not seen in men.
They postulated, “It is also possible the different findings by sex reflect differences in how dietary data collection methodologies are perceived and completed by both men and women,
The present study identified slightly different dietary patterns for men and women in that the healthy dietary pattern was the same except for men it also included oil and vinegar salad dressings, rice and cottage or ricotta cheese,
The unhealthy dietary patterns were also similar with the exception that this pattern in men also contained pizza and hamburgers, fried or battered fish, hot chips or roast potatoes and muesli or porridge,
The difference in dietary patterns may be due to differences in actual intakes or potentially a difference in the accuracy of the FFQ recall between men and women.”
They said future studies were needed to confirm these findings and to understand why differences may occur by sex and potential implications in nutritional epidemiology.
They concluded that their findings could add onto the growing body of evidence that a healthy dietary pattern was associated with better mental health in older people.
Source: British Journal of Nutrition
“Dietary patterns are associated with depressive symptoms in older Australian women but not men”
Authors: Michael J. Hart, et al.