• The Mediterranean diet is associated with decreased feelings of stress and mental distress, according to new research.
• Conversely, components of the Western diet, which include fast food and sugary (high-glycemic index) foods, were positively associated with negative feelings.
• The Mediterranean diet is widely considered one of the best on the planet and has been linked to numerous benefits, including improved heart and brain health.

If you’ve spent any amount of time online reading about diet, you’ve encountered the Mediterranean diet, rich in vegetables, whole grains, and heart-healthy fats like fish. Its myriad benefits include improvements to heart health, blood sugar, and cognitive functioning.

Now, researchers in the field of nutritional neuroscience, which examines nutrition through the lens of neurochemistry, have found that the Mediterranean diet also appears to play a role in improving mood and dealing with stress. On the other hand, the Western diet, known for highly processed foods, red meat, and high-glycemic index foods, appears to exacerbate negative feelings associated with stress.

The findings were published in the journal Nutrition and Health.

Lina Begdache, PhD, RDN, an Associate Professor of Nutritional Neuroscientist, Registered Dietitian, and Senior Author of the research, told Healthline, “We closed a gap in the literature by looking at the impact of diet quality on [the] perception of stress.”

“Our results showed that the Mediterranean diet reduced feelings of distress as well as increased feelings of eustress [positive stress]. Whereas the Western diet lowered the perception of the positive stress and promoted distress,” she said.

Kristin Kirkpatrick, MS, RD, a nutritionist at the Cleveland Clinic, and co-author of Regenerative Health, who wasn’t affiliated with the study, told Healthline, “This research is aligned with others looking at a Mediterranean dietary pattern and its association with depression and anxiety.”

She pointed out that trials including the AMMEND, SMILES, and HELFIMED have all found similar results. They focused specifically on the effects of the diet on depression.

How the study was conducted

The study involved 1591 participants who answered a series of surveys and questionnaires about diet and mood. More than 70% of the participants (1,117) were female. Nearly all participants (1,412) were between the ages of 18-29, while a few were 30 years or older.

Researchers used a validated tool, the food-mood questionnaire (FMQ), which Begdache developed, to explore how food makes someone feel.

They also used a standard measurement for feelings of distress known as the Kessler Scale, which asks respondents to give a numerical rating to indicate the frequency of certain feelings, like “nervous,” “hopeless,” and “worthless.” The Perceived Stress Scale (PSS), which has been used since 1983, asks respondents how frequently they feel various feelings like being able to “control irritations” or whether things were “going your way.”

Begdache and her team then linked how specific components of the Mediterranean and Western diets affected these feelings.

Dark leafy greens, a staple of the Mediterranean diet, were inversely correlated with nearly all of the negative feelings of the Kessler Scale. Meanwhile, components of the Western diet, like fast food and sugary (high-glycemic index) foods, were positively correlated with these negative feelings.

Not only that but many of the same components that were inversely associated with negative feelings were also positively associated with positive feelings. For example, leafy vegetables, whole grains, exercise, nuts, and oats all correlated with feelings like “confident to handle problems” and “able to control irritations.”

“This suggests that these foods not only promoted the positive outlook regarding stress but reduced the negative perception of stress,” said Begdache.

The Western diet wasn’t all bad either.

White meat, eggs, and even red meat, for the most part, showed negative associations with feelings of stress and mental distress and positive associations with positive feelings like confidence.

How food can affect your mood

Nutritional neuroscience takes nutrition science to a new level by investigating the chemistry and neuroscience of how certain foods affect mood. This involves many complex biological systems and pathways, particularly the gut-brain axis, a direct link between the gastrointestinal tract and the brain.

Inflammation, hormones, and neurotransmitters all affect mood and are directly influenced by diet and gut health.

Serotonin, for example, your body’s “feel-good” hormone and neurotransmitter that helps regulate mood, is almost entirely formed in the gut.

“Remember that 95% of your serotonin is coming from your gut. So in the gut, the microbiome is responsible for helping you metabolize and have that serotonin available,” Eva Selhub, MD, a physician and author who specializes in mind-body medicine, told Healthline.

Begdache points out, “Blood sugar fluctuations are the main cause of mental distress and the stress response because serotonin levels become unstable. Consequently, there is loss of appetite control when blood sugar falls.”

Stress increases the hormone cortisol, which can affect weight gain and inflammation.

“A possible nutrient shortage or unbalanced diet (when adhering to a Western diet) may encourage a prolonged cortisol release in order to create a new normal state based on the current dietary circumstances,” said Begdache.

How to begin adopting a Mediterranean diet

“A Mediterranean diet is focused primarily on lean protein, high intake of fresh fruits and vegetables, and limiting alcohol. It can also include fresh fish as a lean protein source that is high in omega-3s. These are all anti-inflammatory; we understand that there are positive benefits of an anti-inflammatory diet due to the gut-brain axis,” said Alyssa Kwan, MS, RD, a Clinical Dietitian in Cardiology at Stanford Medicine who wasn’t affiliated with the research.

Getting started on the Mediterranean diet may feel daunting, but it shouldn’t. It all starts with small changes that should lead to greater mealtime satisfaction, not less.

Selhub recommends the “80-20 rule”, which simply means to eat nutrient dense foods (like those on the Mediterranean diet) 80% of the time, while still leaving room, the other 20%, for less nutritious foods.

“Rather than thinking about removing things from your diet, thinking ‘I can’t have something,’ think about what you can add. Think about adding color to your plate: plants, vegetables, fruits, nuts and seeds, lean proteins, healthy grains, and fatty fish,” said Selhub.

“Start with foods you love from a Mediterranean pattern while reducing ultra-processed and empty-calorie foods. This may begin by swapping white bread for whole grain bread, swapping a piece of fruit or healthy fats for snacks that don’t contain nutrients,” Kirkpatrick added.

The bottom line

New research indicates that components of the Mediterranean diet, such as vegetables, whole grains, and nuts, were inversely associated with negative feelings and stress, while components of a Western diet, like fast food and sugary foods, were positively associated with them.

The Mediterranean diet is widely considered one of the best diets in the world. It includes plenty of vegetables, lean protein, and healthy fats (such as those from fish and nuts).

Not all parts of the Western diet were associated with stress and negative feelings: eggs, white meat, and even red meat had a positive impact on mood.