Read: Nutrition and Mental Health

A magnifying glass focused on a sticky note with the text mental health

Mental health is an intrinsic part of everyone's well-being and quality of life throughout the lifespan — from childhood and adolescence through adulthood.

The CDC states that mental health includes our emotional, psychological, and social well-being. It affects how we think, feel, and act. It also helps determine how we handle stress, relate to others, and make healthy choices.

Conditions such as depression increase the risk for many types of physical health problems, particularly long-lasting conditions like stroke, Type 2 diabetes, heart disease, cancer, dementia, hypertension, chronic pain, and substance use. Similarly, the presence of chronic conditions can increase the risk for mental health issues. The good news is that nutrition can be a powerful ally as we strive toward taking good care of our mental health.

Research on Fruits and Vegetables

In a study of nearly 300,000 Canadians, greater fruit and vegetable consumption was associated with lower odds of depression, psychological distress, self-reported mood and anxiety disorders, and poor perceived mental health. Researchers conclude that since a healthy diet consisting of a high intake of fruits and vegetables is rich in antioxidants, it may consequently dampen the detrimental effects of oxidative stress on mental health.

A common criticism in this area of research is that maybe there’s some inherent personality trait or type of family upbringing that might lead people to simultaneously eat in a healthy way and have better mental well-being, so that diet is then merely correlated with — but incorrectly gives the appearance of helping to cause — the level of well-being. Researchers in Australia circumvented this problem, however, by seeing if “changes in diet are correlated with changes in mental well-being,” in effect studying the “Evolution of Well-Being and Happiness After Increases in the Consumption of Fruit and Vegetables.” Increased fruit and vegetable consumption was predictive of increased happiness, life satisfaction, and well-being.

This study was repeated in the United Kingdom, and researchers there found the same thing. Using the same data set but instead looking for mental disorders, the UK researchers found that eating fruit and vegetables may help to protect against future risk of clinical depression and anxiety as well.

Research on Animal Foods

In an interventional study on diet and depression, anxiety, and stress, researchers split meat eaters up into three groups:

The control group maintained regular intake of animal foods.
The second group ate fish but no other meat.
The third group was put on a vegetarian diet with no eggs.

Researchers found that the egg-free vegetarian group significantly improved, meaning greater reductions in both the Depression/Anxiety/Stress scale and in the Profile of Mood States, a measurement of mood disturbance. Though the fish group did marginally better than the control group, the difference was not statistically significant.

The authors' conclusion: “The complete restriction of flesh foods significantly reduced mood variability in omnivores… Our results suggest that a vegetarian diet can reduce mood variability in omnivores. Perhaps eating less meat can help protect mood in omnivores, particularly important in those susceptible to [mood] disorders.”

Nutrition and BDNF

There is accumulating evidence that brain-derived neurotrophic factor (BDNF) may be playing a role in human depression. BDNF controls the growth of new nerve cells, and low levels may explain the atrophy of specific brain areas among depressed patients.

The Harvard Nurses’ Study followed tens of thousands of women for years and found that those who were eating the most flavonoids appeared to reduce their risk of depression. Flavonoids occur naturally in plants, especially fruits, vegetables, and legumes. In a randomized controlled trial, after 18 weeks, the high-flavonoid group got a significant boost in BDNF levels, which corresponded with an improvement in cognitive performance. The BDNF boost may help explain why each additional daily serving of fruits or vegetables is associated with a 3% decrease in the risk of depression.

A single high-fat meal can drop BDNF levels within hours; perhaps that helps explain why increased consumption of saturated fats in a high-fat diet may contribute to brain dysfunction such as neurodegenerative diseases, long-term memory loss, and cognitive impairment. This might also help explain why the Standard American Diet (SAD) has been linked to a higher risk of depression; dietary factors may be modulating the levels of BDNF in people who consume the SAD diet.

CDC. About Mental Health. https://www.cdc.gov/mentalhealth/learn/index.htm
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