Mediterranean diet linked to lower anxiety and stress levels, but no effect on depression, study shows

By Neha MathurJan 30 2024Reviewed by Danielle Ellis, B.Sc.

In a recent study published in Nutrients, researchers explored the association between adherence to a Mediterranean diet (MedDiet) and the severity of symptoms of depression, anxiety, and stress in adults aged ≥60 years independently living in Australia.

Background

Literature on the benefits associated with the maintenance of physical and mental function with age is compelling. Mental health disorders, especially depression and anxiety, show marked heterogeneity in clinical presentation, multiple etiologies, and complex pathophysiology.

Diet is a modifiable risk factor for mental health issues. Research has endorsed the MedDiet to reduce chronic disease(s) risk and support healthy aging.

Studies have found that adherence to any anti-inflammatory diet has an inverse relationship with depression in younger and middle-aged adults; however, these findings remain inconsistent. This may be due to the heterogeneity in the study designs used (e.g., longitudinal, cross-sectional), differences in the outcomes (anxiety vs. depression) evaluated, modalities used to identify depression or depressive symptoms, or population subgroups studied (young, middle-aged, older).

Overall, there is a lack of evidence regarding mental health etiology and its association with lifestyle habits, such as diet, especially in older adults.

Study methodology

Researchers conducted a 75-item online survey among older adults from Australia to understand the potential association between MedDiet adherence, including its dietary constituents, and the severity of depression, anxiety, and stress symptoms.

Further, they used the DASS-21, a screening tool with seven items each for measuring the severity of depression, anxiety, and stress symptoms. In previous works, it has demonstrated good psychometric properties in older adults, including good internal consistency and high convergent validity.

Next, the team evaluated the MedDiet Adherence using the 14-item MEDAS, where they scored each question as zero or one, with a higher score indicating higher adherence.

The statistical analysis involved the use of linear regression to examine the association between MedDiet adherence and symptoms of depression, anxiety, and stress while controlling for covariates (e.g., cognitive status). They also adjusted for cognitive status (a potential confounder) using validated tools, such as Lawton's iADLs scale and AD8 dementia screening intervention.

Furthermore, the team presented continuous variables as means/medians, conducted t-tests to compare demographic characteristics between genders, and performed regression diagnostics.

Results

Of 303, 294 older Australians completed components of the questionnaire used in the final analysis, of which 201 were females, 91 were males, and two were unspecified.

A significant number of participants reported mild symptoms of depression (n=99), anxiety (n=80), and stress (n=47), according to the DASS-21. However, there were no significant differences in these symptoms across genders in the study sample.

The adherence to the MedDiet in the entire sample was moderate, with females showing greater adherence than males.

While adherence to MedDiet was inversely associated with the severity of anxiety and stress symptoms in community-dwelling older Australians, it was unrelated to any depressive symptomatology in them.

Depression is multidimensional, involving biological, psychological, and social risk factors. Thus, it is unlikely that following a healthy dietary pattern alone can attenuate its symptoms. 

Further, the results revealed the effect(s) of specific dietary components of a MedDiet, as defined by the MEDAS.

Higher vegetable intake was inversely associated with symptoms of depression, while fruit intake was inversely associated with stress-related symptoms. Additionally, nut consumption was inversely associated with anxiety and stress symptoms, legume intake was inversely related to anxiety symptoms' severity, and low consumption of sugar-sweetened beverages (less than 250mL per day) was associated with less severe anxiety symptoms. 

Conclusion

Overall, the study results contribute to the literature in support of adherence to a healthy dietary pattern to combat mental health disorders, especially in older adults. 

Prospective studies and robust clinical trials with adequate samples, particularly in older adults with established mental health disorders, should further investigate these findings. Studies should also explore the inconsistencies in results between participants of different ages.

In the future, this will help position MedDiet interventions as an adjunctive treatment in psychiatric practice for the management of mental health symptomology, allowing practitioners to adopt evidence-based nutritional medicine for the treatment of mental health disorders in older adults.