It seems like common sense but eating well probably leads to a healthy mind. We know we are a mind-body so how could eating a diet laden with junk lead to a healthy mind? The first study review below looks at supplementation (multivitamin/mineral supplementation) and it's effect on stress and mood states. Supplements do not make up for a poor diet but in this case they were looking at how dietary inadequacies might effect mood states. All the studies ran at least 28 days. Overall supplementation had a beneficial effect on perceived stress and mild psychiatric symptoms. Supplements containing the highest levels of B vitamins may be more effective in improving mood states.
The other studies I find more interesting because they looked at diet not supplements and its effect on depression. In one women who ate a traditional diet were 30% less likely to have major depressive disorder, dysthymia and anxiety compared to their counterparts who consumed a Western diet.
A traditional dietary pattern comprised mainly vegetables, fruit, beef, lamb, fish, and whole-grain foods, while a western pattern comprised foods such as meat pies, processed meats, pizza, chips, hamburgers, white bread, sugar, flavored milk drinks, and beer. A modern pattern consisted of foods such as fruits and salads plus fish, tofu, beans, nuts, yogurt, and red wine.
There was an unexpected finding in women who ate a modern diet but this may have been because those women were trying to improve their depressive symptoms through a healthier diet. In another study a diet of whole foods (heavy in vegetables, fruits and fish) compared to a diet loaded with sweet desserts, fried food, processed meat, refined grains and high fat dairy were compared for odds of developing depression. The highest adherence to the whole foods diet had the lowest odds of depression. In the last study the adherence to a Mediterranean Dietetary pattern was associated with a lower risk of depression and was found to have a protective role in the prevention of depressive disorders.
I am not an advocate of any particular diet. I see each person as an individual and they know best what suites them and every 'diet' can have a time and place in a persons life. A diet based on whole foods, made at home, seasonally respectful and varied will always be the best choice.
Effects of vitamin and mineral supplementation on stress, mild psychiatric symptoms, and mood in nonclinical samples: a meta-analysis.
Psychosom Med. 2013 Feb;75(2):144-53.
OBJECTIVE: Biochemical processes in the brain affect mood. Minor dietary inadequacies, which are responsible for a small decline in an enzyme's efficiency, could cumulatively influence mood states. When diet does not provide an optimal intake of micronutrients, supplementation is expected to benefit mood. This meta-analysis evaluated the influence of diet supplementation on mood in nonclinical samples.
METHODS: Databases were evaluated and studies were included if they considered aspects of stress, mild psychiatric symptoms, or mood in the general population; were randomized and placebo-controlled; evaluated the influence of multivitamin/mineral supplements for at least 28 days. Eight studies that met the inclusion criteria were integrated using meta-analysis.
RESULTS: Supplementation reduced the levels of perceived stress (standard mean difference [SMD]=0.35; 95% confidence interval [CI]=0.47-0.22; p=.001), mild psychiatric symptoms (SMD=0.30; 95% CI=0.43-0.18; p=.001), and anxiety (SMD=0.32; 95% CI=0.48-0.16; p<.001), but not depression (SMD=0.20; 95% CI=0.42-0.030; p<.089). Fatigue (SMD=0.27; 95% CI=0.40-0.146; p<.001) and confusion (SMD=0.225; 95% CI=0.38-0.07; p<.003) were also reduced.
CONCLUSIONS: Micronutrient supplementation has a beneficial effect on perceived stress, mild psychiatric symptoms, and aspects of everyday mood in apparently healthy individuals. Supplements containing high doses of B vitamins may be more effective in improving mood states. Questions about optimal levels of micronutrient intake, optimal doses, and active ingredients arise.
Western Style Diet Associated with Depression
The 12-item General Health Questionnaire (GHQ-12) was used to measure psychological symptoms in 1046 women aged 20-93 years. Using a food frequency questionnaire, women were categorized as eating a traditional diet pattern characterized by vegetables, fruit, meat, fish, and whole grains, or a Western diet pattern of processed or fried foods, refined grains, sugary products, and beer. After adjusting for age, socioeconomic status, education, and health behaviors, women eating a traditional diet were 30% less likely to have major depression, dysthymia, and anxiety disorders compared to their counterparts who consumed a Western diet. The Western diet eating pattern was associated with a 50% increased likelihood of depression. The researchers emphasized that the traditional diet contained high quality lean meat. The study took place in Australia where the beef and lamb are pasture raised, and therefore have a better essential fatty acid profile than all grain raised beef in America. An unexpected finding was that women who ate a 'modern' diet of fruits, salads, fish, tofu, beans, nuts, yogurt, and red wine had a higher, rather than lower, likelihood of depression among younger educated women. This may be due to these women attempting to improve their depressive symptoms by consuming a healthier diet. There was no association between the Western diet and an increased risk of anxiety.
Am J Psychiatry. 2010 Mar;167(3):305-11. Epub 2010 Jan 4.
Association of Western and traditional diets with depression and anxiety in women.
Whole Food Diet Associated with Lower Odds of Depression
Analysis of dietary patterns was collected from 3486 participants (26.6% women, mean age 55.6 years). Participants were either identified as having a whole food diet that was heavily loaded by vegetables, fruits and fish, or a processed food diet heavily loaded by sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products. Self-reported depression was assessed 5 years later. The highest tertile of the whole food eating pattern had the lowest odds of depression (Center for Epidemiologic Studies - Depression) than those in the lowest tertile. A high processed food diet was associated with increased odds of depression. A processed food dietary pattern is a risk factor for depression 5 years later, whereas a whole food pattern is protective.
Br J Psychiatry. 2009 Nov;195(5):408-13.
Dietary pattern and depressive symptoms in middle age.
Mediterranean Dietary Pattern May Prevent Depressive Disorders
A total of 10,094 healthy Spanish participants completed a 136-item food frequency questionnaire to assess their adherence to a Mediterranean Dietary Pattern (MDP). The MDP score was weighted positively for the consumption of vegetables, fruits and nuts, cereal, legumes and fish, monosaturated to saturated fatty acids and moderate alcohol consumption. The median follow-up was 4.4 years. Depression was classified as having a physician-made diagnosis of clinical depression and/or antidepressant medication use during follow-up that was not present as baseline. The adherence to the MDP was associated with lower risk of depression and higher adherence to the MDP was associated with lower risk. The MDP has a potential protective role in the prevention of depressive disorders.
Arch Gen Psychiatry. 2009 Oct;66(10):1090-8.
Association of the Mediterranean dietary pattern with the incidence of depression: the Seguimiento Universidad de Navarra/University of Navarra follow-up (SUN) cohort.