Diet and depression

Research has shown that eating a diet rich in fruits, vegetables, legumes, olive oil and fish can help to reduce the risk of cancer, heart disease, diabetes and even Alzheimer's disease. And now a new study indicates that it may also help to prevent depression.

The Mediterranean diet has long been thought to explain the long life expectancy of southern Europeans. And because Mediterranean countries also have lower rates of depression and suicide than many other countries, researchers were curious about whether their diet might also affect mental health.

For the study, published in Archives of General Psychiatry, researchers looked at 10,000 healthy Spanish university graduates. Participants were asked to complete a food questionnaire at the start of the study, and they were then followed over the next four and a half years. In particular, they were asked if their diets contained the following components of a traditional Mediterranean diet:

-- A high ratio of monounsaturated fatty acids (such as those found in olive oil) to saturated fatty acids (found in animal fats like butter and meat).

-- Moderate use of alcohol and dairy products.

-- Low intake of meat.

-- High intake of legumes, fruits, nuts, cereals, vegetables and fish.

The results? Those who ate 'Mediterranean-style' were about 30 per cent less likely to be diagnosed with depression.

Researchers say that the fatty acids in olive oil may play a role in lowering the rates of depression. "However, the role of the overall dietary pattern may be more important than the effect of single components," writes lead study author Almudena Sánchez-Villegas of University of Las Palmas de Gran Canaria.

"It is plausible that the synergistic combination of a sufficient provision of omega-three fatty acids together with other natural unsaturated fatty acids and antioxidants from olive oil and nuts, flavonoids and other phytochemicals from fruit and other plant foods and large amounts of natural folates and other B vitamins in the overall Mediterranean dietary pattern may exert a fair degree of protection against depression."

More studies are needed to show a direct cause and effect from eating a Mediterranean-style diet and lowering depression, researchers say.

Make your diet more Mediterranean

So what is the Mediterranean diet exactly? Over a dozen countries border the Mediterranean Sea, making it difficult to designate one official 'Mediterranean diet'. Diets vary between countries and regions and often reflect differences in culture, ethnic background, religion, economy and agricultural production. But the common Mediterranean-inspired menu generally adheres to these principles:

-- A high consumption of fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds.

-- Olive oil is used as an important source of monounsaturated fat.

-- Dairy products, eggs and poultry are consumed in low to moderate amounts.

-- Little red meat is eaten.

-- Herbs and spices are used to flavour foods, which either replaces or reduces salt.

-- Red wine is consumed in moderate amounts.

Sources: Archives of General Psychiatry, October 2009; American Medical Association news release; American Heart Association; The Mayo Clinic.

Photo ©iStockphoto.com/ Steve Debenport Photography

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