Healthy eating in older age may do more than support general wellness. A long Swedish study found that diets tied to brain and heart health slowed the buildup of chronic disease, while inflammatory eating patterns appeared to push that burden higher.

Growing older often brings new health challenges. Heart disease, dementia, depression and diabetes become more common with age. For many older adults, these conditions do not appear alone. They build over time, creating a complex web of chronic illness that affects daily life, independence and well-being.

Now, a major long-term study from Sweden suggests that diet may influence how quickly those diseases accumulate. Researchers from Karolinska Institutet found that healthy eating patterns slowed the buildup of chronic diseases in older adults over 15 years. In contrast, diets linked to inflammation appeared to speed that process up.

The findings followed more than 2,400 older adults and examined how four different dietary patterns affected aging and disease progression.

“Our results show how important diet is in influencing the development of multimorbidity in ageing populations,” said co-first author Adrián Carballo-Casla.

Researchers focused on a condition known as multimorbidity, which means living with two or more chronic diseases at the same time. Multimorbidity has become a major public health concern as populations age worldwide.

The study included 2,473 adults living in Stockholm as part of the Swedish National Study on Aging and Care in Kungsholmen. Participants were at least 60 years old when the research began between 2001 and 2004. Their average age was 71.5 years, and about 61% were women.

At the start of the study, more than 84% already had multiple chronic conditions.

Scientists tracked participants for up to 15 years. Adults younger than 78 underwent health assessments every six years, while older participants were evaluated every three years. Researchers monitored the development of diseases affecting the cardiovascular system, the brain and nervous system and the musculoskeletal system.

To understand how food choices shaped health over time, the researchers examined four established dietary patterns.

Three diets were considered healthy. These included the MIND diet, the Alternative Healthy Eating Index, known as AHEI, and the Alternative Mediterranean Diet, called AMED.

The MIND diet combines parts of the Mediterranean and DASH diets and was designed to support brain health and reduce dementia risk. It emphasizes leafy greens, berries, vegetables, whole grains and healthy fats while limiting foods high in saturated fat.

The AHEI focuses on dietary habits linked to lower chronic disease risk overall. The AMED adapts the traditional Mediterranean diet for Western eating habits.

The fourth dietary pattern was very different. Researchers used the Empirical Dietary Inflammatory Index, or EDII, to measure diets associated with higher inflammation. These diets contained more red and processed meat, refined grains and sugary drinks while including fewer vegetables, tea and coffee.

Participants completed detailed food questionnaires covering 98 food items. Researchers used those responses to calculate how closely each person followed the different eating patterns.

The results showed clear differences between healthy and inflammatory diets.

Older adults who followed the MIND, AHEI and AMED diets developed chronic diseases more slowly over time. Those with higher scores for inflammatory eating patterns developed diseases faster.

The strongest results appeared with the AHEI and MIND diets. Over 15 years, participants with the highest AHEI adherence developed an average of 2.54 fewer chronic diseases than those with the lowest adherence. For the MIND diet, the difference reached 2.01 fewer diseases.

Meanwhile, participants with the most inflammatory diets developed an average of 2.13 more chronic diseases than those with the least inflammatory diets.

The protective effects appeared especially strong for cardiovascular and neuropsychiatric diseases, including conditions linked to the heart, blood vessels and brain.

Researchers found no clear connection between diet and musculoskeletal diseases involving muscles, bones and joints.

Scientists believe inflammation could explain much of the relationship between diet and disease progression.

Healthy dietary patterns often reduce inflammatory markers in the body, including substances such as C-reactive protein and interleukin-6. Inflammatory diets tend to increase them.

As people age, many experience a slow rise in chronic low-grade inflammation, sometimes called “inflammaging.” This process has been linked to heart disease, cognitive decline and other chronic illnesses.

The foods emphasized in the healthy diets may help counter that process. Vegetables, fruits, nuts, legumes and unsaturated fats contain compounds linked to lower inflammation and improved metabolic health.

By contrast, diets heavy in processed meat, sugary drinks and refined grains may place more stress on the body over time.

The study found that healthier diets particularly slowed the buildup of cardiovascular disease and neuropsychiatric conditions. That may reflect improvements in blood pressure, cholesterol, blood sugar and brain health linked to these eating patterns.

Researchers also explored whether age and sex influenced the findings.

The protective effects of healthy diets on cardiovascular disease appeared stronger in women. In men, the same associations did not reach statistical significance.

Age also seemed to matter. The MIND diet showed especially strong associations in adults 78 and older, particularly for total disease accumulation and neuropsychiatric conditions.

Still, after additional statistical adjustments, researchers found that the overall benefits of healthy eating remained broadly consistent across age groups and sexes.

The team also used advanced statistical modeling to track how diseases accumulated over time. They identified several distinct disease trajectories, ranging from slower to faster accumulation patterns.

Participants with stronger adherence to the MIND and AHEI diets were less likely to fall into faster disease progression groups. Those following inflammatory diets were more likely to experience rapid disease accumulation.

For cardiovascular diseases, higher inflammatory diet scores increased the probability of belonging to the fastest progression group. For neuropsychiatric diseases, healthier eating patterns reduced the likelihood of rapid decline.

Researchers also tested whether the findings held up under different conditions. Even after excluding participants with possible cognitive impairment or dietary reporting errors, the overall patterns remained similar.

One important message from the study is that healthier eating habits may still matter well into older age.

Many people assume that lifestyle changes become less meaningful later in life. But the findings suggest otherwise. Even among adults in their late 70s and 80s, healthier dietary patterns were linked to slower accumulation of chronic disease.

The researchers caution that the study does not prove direct cause and effect. Dietary information was self-reported, and the population mainly included well-educated urban adults in Sweden. Still, the long follow-up period and repeated dietary assessments strengthen the findings.

The next step, according to the research team, is identifying which dietary recommendations may have the greatest impact on healthy aging and determining which groups of older adults may benefit most.

This study highlights diet as one of the few modifiable factors that may influence how quickly chronic diseases build up with age. The findings suggest that healthier eating patterns could help older adults maintain quality of life for longer by slowing the progression of illnesses tied to the heart and brain.

The research may also shape future public health recommendations for aging populations. As life expectancy rises globally, healthcare systems face growing pressure from multimorbidity and age-related disease. Strategies that delay disease accumulation, even modestly, could reduce healthcare costs and improve independence for millions of people.

Researchers now hope to determine which dietary changes offer the greatest long-term benefits and whether recommendations should differ based on age, sex or existing health conditions. The findings also reinforce the idea that healthy eating is not only about preventing a single disease, but about shaping the overall pace of aging itself.

Research findings are available online in the journal Nature Aging.