Simple lifestyle changes can prevent diabetes and dementia

A growing body of research points to a deceptively simple prescription for healthy aging: eat Mediterranean-style, move a bit more, and get structured support. 

Two major studies released this year – one a six-year clinical trial in Spain, the other a decades-long U.S. cohort analysis – reach the same conclusion from different angles. 

The first, published in the journal Annals of Internal Medicine, shows that a calorie-smart Mediterranean plan with moderate exercise and coaching can cut new cases of type 2 diabetes by nearly a third. 

The second, published in the journal Nature Medicine, links a Mediterranean diet to lower dementia risk and slower cognitive decline, with the biggest brain benefits in people at the highest inherited risk for Alzheimer’s disease.

A win for metabolic health

The PREDIMED-Plus trial, the largest nutrition study ever run in Europe, followed 4,746 adults aged 55–75 with obesity and metabolic syndrome, but no diabetes or cardiovascular disease.

The trial was conducted across more than 100 primary-care centers in Spain. Participants were split into two groups.

One followed a traditional Mediterranean diet without calorie limits or exercise advice. The other adopted an “optimized” version that cut about 600 calories a day, added moderate activity like brisk walking and strength training, and included ongoing professional support.

After six years, the optimized group saw a 31% relative reduction in incident type 2 diabetes compared with controls. They also lost more weight and shrank their waistlines more. 

Preventing new diabetes cases

In population terms, that prevented roughly three new diabetes diagnoses for every 100 participants – a meaningful public-health gain in a world where type 2 diabetes already affects more than 530 million people.

“Diabetes is the first solid clinical outcome for which we have shown  – using the strongest available evidence  – that the Mediterranean diet with calorie reduction, physical activity, and weight loss is a highly effective preventive tool,” said Miguel Ángel Martínez-González,  a professor of preventive medicine and public health at the University of Navarra.

“Applied at scale in at-risk populations, these modest and sustained lifestyle changes could prevent thousands of new diagnoses every year.”

Mechanistically, the pattern’s emphasis on extra-virgin olive oil, nuts, legumes, whole grains, fish, fruits, and vegetables is thought to improve insulin sensitivity and tamp down chronic inflammation – effects magnified by weight loss and movement. 

“The Mediterranean diet acts synergistically to improve insulin sensitivity and reduce inflammation. With PREDIMED-Plus, we demonstrate that combining calorie control and physical activity enhances these benefits,” said Miguel Ruiz-Canela, the chair of preventive medicine and public health at the University of Navarra.

Mediterranean diet and dementia 

A complementary study led by Mass General Brigham followed 4,215 women in the Nurses’ Health Study (validated in 1,490 men in the Health Professionals Follow-Up Study) from the late 1980s and 1990s through 2023. 

The researchers assessed long-term dietary patterns with food-frequency questionnaires, profiled blood metabolites, genotyped participants to estimate inherited Alzheimer’s risk, and tracked new dementia diagnoses. A subset of 1,037 women also completed regular telephone-based cognitive testing.

People adhering more closely to a Mediterranean-style diet had a lower risk of developing dementia and showed slower cognitive decline. 

Crucially, the protective association was strongest among individuals with two copies of APOE4 – the most powerful common genetic risk factor for late-onset Alzheimer’s disease – suggesting that diet may help offset inherited vulnerability.

“One reason we wanted to study the Mediterranean diet is because it is the only dietary pattern that has been causally linked to cognitive benefits in a randomized trial,” said first author Yuxi Liu, a research fellow at Bingham and Women’s Hospital.

“We wanted to see whether this benefit might be different in people with varying genetic backgrounds, and to examine the role of blood metabolites, the small molecules that reflect how the body processes food and carries out normal functions.” 

Dietary strategies for healthy aging

According to Liu, the findings suggest that dietary strategies, specifically the Mediterranean diet, could help reduce the risk of cognitive decline and stave off dementia by broadly influencing key metabolic pathways.

“This recommendation applies broadly, but it may be even more important for individuals at a higher genetic risk, such as those carrying two copies of the APOE4 genetic variant,” said Liu.

The authors acknowledge limits – participants were predominantly well-educated and of European ancestry, and most people don’t know their APOE status – but the signal is consistent with prior trials and mechanistic work.

Reducing diabetes and dementia risks

No single diet cures all ills. But two high-quality studies in top journals now show that a Mediterranean-style pattern – especially when paired with modest calorie reduction, regular activity, and support – can meaningfully reduce the risk of type 2 diabetes. 

At the same time, long-term adherence also tracks with lower dementia risk and slower cognitive decline, most notably among people with the highest genetic risk. 

In an era of expensive new drugs, these findings are a reminder that small, sustained lifestyle shifts still deliver large, compounding dividends – for body and brain alike.

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