Eating a diet rich in fruits, vegetables, fish and olive oil may help keep the mind strong even into old age, according to new research.

Older adults in England who followed a Mediterranean diet — which is primarily composed of the above foods — during the height of the COVID-19 pandemic reported higher psychological well-being than peers who did not.

The researchers tracked more than 3,000 adults between the ages of 50 and 90 to determine how their daily food choices related to their long-term outlook on life, according to a press release.

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The participants filled out specialized surveys that measured positive psychological traits, including their sense of autonomy, life satisfaction, purpose and control over daily routines.

Each participant also received a score based on how closely their eating habits matched a traditional Mediterranean dietary pattern.

Adults who stuck closely to the Mediterranean diet reported a significantly stronger sense of overall well-being.

This finding held even after researchers accounted for factors like income, education, physical activity, smoking habits and general physical health.

The boost in well-being did not appear to be driven by differences in caloric intake, which suggests the specific types of food played an important role.

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As the researchers tracked the participants over several years, they were able to measure how their well-being shifted during the early months of the pandemic.

While emotional well-being and happiness dropped across the entire group during the lockdowns, the study – which was published in BMJ Open – showed the decline was less intense for people who stuck to the Mediterranean diet.

Previous research points to a few explanations for this.

“This study shows what we’ve been seeing in other research,” Kim Kulp, registered dietitian nutritionist and owner of the Gut Health Connection in the San Francisco Bay Area, told Fox News Digital.

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The Mediterranean diet is naturally rich in anti-inflammatory nutrients, including omega-3 fatty acids from fish and antioxidants called polyphenols found in extra-virgin olive oil.

These nutrients help to lower inflammation in the brain and support a healthy gut microbiome, which is directly linked to the chemical production of mood-regulating hormones, experts say.

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“Since the Mediterranean diet is loaded with a variety of plant foods, it provides an increase in nutrients for the body and brain, special compounds that reduce inflammation, and prebiotics to feed the good gut microbes,” said Kulp, who was not involved in the study.

Researchers noted some limitations to the data, including the fact that the study relied on self-reported dietary surveys, which can sometimes be inaccurate.

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Additionally, the participants who completed the tracking tended to be healthier and wealthier than the general public, meaning the results might not fully apply to more diverse or vulnerable populations.

“There were only two days of dietary data, and the psychological well-being test was only administered on two occasions, both early on during COVID,” Kulp noted. “Two days of data may not be enough to form conclusions.”

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Because the study was observational, it could not prove a direct cause-and-effect relationship between the diet and improved mental health, the researchers acknowledged.

“Eating a diet rich in fruits, vegetables, whole grains, nuts, seeds and legumes provides the ultimate combination of nutrients to improve overall health as we age,” said Kulp.

“Together, this diet can help reduce stress and depression and improve a sense of well-being, even during the toughest times.”