Mediterranean style eating and mood: what trials show so far

The Mediterranean style of eating comes up often in talk about food and mood, and a handful of trials have looked at it. The whole body of trials is still small. This note explains what the pattern is, describes one well known trial in some detail, summarises a 2024 review of several trials, and says where the limits lie.

What the pattern is

There is no single Mediterranean diet. The American Heart Association calls the term generic, based on the traditional eating habits of countries bordering the Mediterranean Sea, of which there are at least 16. A Mediterranean style diet typically includes plenty of fruits, vegetables, bread and other grains, potatoes, beans, nuts and seeds, with olive oil as the main fat. Dairy products, eggs, fish and poultry appear in low to moderate amounts, and fish and poultry are more common than red meat. Fruit is a common dessert instead of sweets.

Because the pattern is loosely defined, trials that test it differ in what they actually ask people to eat. That is one reason results are hard to compare.

The SMILES trial

The study most often cited is SMILES, published in 2017 in BMC Medicine. It was a 12 week randomised controlled trial in adults with moderate to severe depression, and the diet was an addition to their existing treatment rather than a replacement for it. One group received seven individual sessions with a clinical dietitian. The comparison group received the same number of sessions of social support, so that both groups had equal attention.

Sixty seven people took part (33 in the diet group and 34 in the comparison group). Remission, defined by the authors as a score under 10 on a standard depression rating scale, was reached by 32.3% of the diet group and 8.0% of the comparison group. The authors calculated that about four people would need to follow the diet programme for one additional person to reach remission, although the confidence interval around that figure is wide (2.3 to 27.8). The trial was described as single blind, and people cannot easily be blind to what they are eating, so expectation may have played some part.

Those are encouraging numbers from a careful design. They also come from 67 people over three months, which is small and short. A trial of that size can point a direction without settling the question.

The wider picture

A 2024 analysis in Nutrition Reviews, described by Harvard Health, brought together five randomised trials involving 1,507 adults aged 22 to 53 with mild, moderate or severe depression. The trials lasted from 6 to 48 weeks, and participants in the intervention groups were advised on how to change their eating habits toward a Mediterranean style. Those who followed the diet had a greater reduction in depression symptoms than those in control groups.

Harvard Health is careful about what this means. The researchers could not prove that a Mediterranean diet eases depression, only that an association exists. Five trials with differing designs, lengths and comparison groups is a thin foundation. It is also worth remembering that people who are asked to change how they eat are often getting more support and structure in their week, which may help mood independently of any single food.

Using this sensibly

Nothing in these studies suggests that food can stand in for treatment. In SMILES, the diet was added to usual care. People already working with a doctor or licensed therapist should keep doing so, and nobody should change or stop prescribed medicine because of an eating plan. A person with a medical condition, food allergies or a history of disordered eating should check with their own clinician or a registered dietitian before changing how they eat.

For readers who simply like the sound of the pattern, the AHA description is a reasonable starting point, and the cost of trying more vegetables, beans and olive oil is low. Eating is one part of a wider picture that includes sleep, company and movement, covered in notes such as exercise and mood, and supplements are a separate question, discussed in the note on omega 3 and mood. The full set of food notes sits on the food and mood shelf.

Anyone in crisis, or thinking about harming themselves, should contact local emergency services or a crisis line immediately.

The short version

A Mediterranean style pattern means mostly plant foods, olive oil, and moderate fish and poultry. A small 12 week trial and a 2024 review of five trials found lower depression symptoms with this way of eating, but the trials were few, short and varied, and the evidence is early. Food can sit alongside treatment, and a reader's own clinician has the final word on both.