How solid is the science behind the so-called "healthy brain" diet?

Researchers from around the world have served the scientific community with new data recently that help explain why a Mediterranean diet is good for brain health, Scientific American reports. While there is no single ingredient that is sure to boost your mood or keep you sharp well into your old age, the correlation between mental well-being and a diet that is rich in fruits, vegetables, lean protein, and olive oil gets stronger every year. Here are some of the strongest conclusions to date cited by Scientific American.

  • Fish and other foods with high levels of omega-3 fatty acids may fight depression.
  • Fermented foods such as pickles and sauerkraut may decrease anxiety.
  • Antioxidant-rich fruits and green tea may prevent dementia.

One of the newest studies in the field of brain health shows why Western diets (typically higher in sugar and fatty meat than a Mediterranean diet) can be bad for the brain. In September, University of Melbourne nutritional psychiatry researcher Felice Jacka discovered that Western diets can literally shrink your brain. Jacka and her colleagues studied a group of adults and determined through MRI scans that after eating a Western diet for four years they had a significantly smaller left hippocampus, a part of the brain that is essential for memory formation. The subjects also experienced higher levels of mood disorders.

"[T]he data show that the main constituents of a healthy brain diet include fruits, vegetables, legumes, nuts, fish, lean meats, and healthy fats such as olive oil," Jacka told Scientific American.

Also last summer, nutritional epidemiologist Martha Morris of Rush University in Chicago found that combining the Mediterranean diet with a high-nutrient, low-salt diet designed to help avoid hypertension may delay cognitive decline and prevent Alzheimer's. Morris and her colleagues tested the cognitive ability of nearly 1,000 adults and discovered that those who had followed the combination diet had the same cognitive scores of people who were seven years younger. 

The results came shortly after a summer study conducted by neuroscientists at the University of Bordeaux, who drew a connection between a Mediterranean diet and the preservation of the brain's neuronal connections. The neuroscientists identified the connection by using a technique called voxel-based morphometry that can detect small changes in brain anatomy.

While the science supporting healthy brain diets is growing every year, Harvard Medical School psychiatrist Emily Deans offered a necessary caveat: Humans have "a long way to go before we fully understand the brain-diet relation," she told Scientific American.