A team of Iranian researchers found that women who adhered to healthy eating guidelines had a 49% lower risk of anxiety and a 45% lower risk of depression, and healthy eaters aged 40 or younger were 58% less likely to suffer from anxiety and 51% less likely to suffer from depression.
“We found evidence indicating that greater adherence to AHEI (Alternative Healthy Eating Index-2010) was associated with lower odds of anxiety and depression. More adherence to AHEI-2010 was associated with a reduced risk of mental disorders in women, as well as in those who were 40 years or younger,” wrote the researchers in the British Journal of Nutrition.
B vitamins, antioxidants and omega-3s were singled out as potentially important nutrients for cognitive health.
First large Middle Eastern study
Whilst several studies in western countries have shown a protective association between adherence to healthy eating guidelines and mental disorders, there is limited data in this respect for Middle Eastern populations. To fill this knowledge gap, the Iranian researchers examined the association between adherence to healthy eating guidelines, as measured by AHEI-2010, in a sample of 3663 adults.
The two-phase, cross-sectional study was carried out within the framework of the ‘Study on the Epidemiology of Psychological-Alimentary Health and Nutrition’, a project that involved Iranian adults working in 50 healthcare centres affiliated to Isfahan University of Medical Sciences.
Participants completed two questionnaires, one on dietary behaviours, such as the frequency of consumption of foods and portion sizes, and the other on psychological distress and mental disorders.
Alternative Healthy Eating Index
AHEI-2010 evaluates the ‘healthiness’ of a diet by measuring intakes of 11 food groups: fruit, vegetables, whole grains, nuts and legumes, omega-3s (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)), polyunsaturated fats (PUFA), alcohol, sugar-sweetened drinks and fruit juice, red and processed meat, trans-fat and sodium.
Individuals who ate the most fruit, vegetables, whole grains, nuts and legumes, omega-3s and PUFA were given a score of 10, and those who ate the lowest amount of these foods were given a score of 1.
Those who ranked highest on this scale were more likely to be women, older and more educated, compared with those at the bottom of the scale.
In the second phase, the Iranian version of the Hospital Anxiety and Depression Scale (HADS) was used to screen participants for anxiety and depression. The data from both phases was merged.
The prevalence of anxiety was 15.2% (10.8% men and 18.3% women), whilst depression was recorded in 30% of participants (22.9% men and 35.1% women).
Gender divide
Greater adherence to the healthy eating guidelines was associated with a lower prevalence of anxiety and depression among women, but not men.
“After controlling for potential confounders, there were no significant associations between adherence to AHEI-2010 and frequency of anxiety or depression in men,” wrote the researchers.
They found that women in the highest categories of AHEI-2010 had 49% and 45% lower odds of having anxiety and depression respectively compared with those in the lowest category - even after adjustment for potential confounders.
They suggested that lower prevalence of anxiety and depression in male participants might explain this apparent disparity.
Whilst no significant associations were found between adherence to AHEI-2010 and mental disorders in the over 40s, those who were aged 40 or under and ate healthily were shown to have a 58% and 51% lower chance of suffering from anxiety and depression respectively.
Why?
The researchers offered several explanations for the link between healthy eating and better mental health: “High content of folate, B vitamins and antioxidants in the healthy eating pattern might reduce neuronal damage of oxidative stress. Because of the high levels of inflammatory biomarkers and depressive symptoms, anti-inflammatory properties of foods included in AHEI have been shown to reduce concentrations of monoamines. Moreover, high levels of PUFA and n-3 fatty acids presented in oily fish and other components of AHEI are possible mechanisms.”
They noted a large cohort study was required to provide evidence of a “causal relationship” between healthy eating and mental health.
Source: British Journal of Nutrition
2016, 116, 335–342 doi:10.1017/S0007114516001926
“Adherence to Alternative Healthy Eating Index in relation to depression and anxiety in Iranian adults”
Authors: Parvane Saneei, Maryam Hajishafiee, Ammar Hassanzadeh Keshteli, Hamid Afshar, Ahmad Esmaillzadeh and Peyman Adibi