Lower-inflammatory diet may help delay or reduce dementia risk – even in older people at risk of Alzheimer’s

Diet has long been linked to dementia risk, but new research suggests that it’s never too late to start eating better to stave off the disease 

Researchers found that older adults who stuck more closely to a healthy, lower-inflammatory diet had a reduced risk of developing dementia – even if they already had biological warning signs linked to Alzheimer’s disease.

The study, led by teams from Karolinska Institutet in Sweden and the University of Ljubljana in Slovenia, followed 1,865 Swedes aged 60 and over for an average of 8.4 years.

The study, published in JAMA Network Open, aimed to find a link between diet quality and the risk of developing dementia later in life.

Participants filled in detailed food questionnaires and were scored on how closely they followed three different healthy eating patterns: a Mediterranean-style diet, the Alternative Healthy Eating Index and the reversed Empirical Dietary Inflammatory Index.

The Mediterranean diet, with its focus on wholegrains, fish, healthy oils and fresh vegetables, is regularly hailed as one of the best ways to eat for long-term health.

The lesser-known eating plans follow similar principles. The Alternative Healthy Eating Index focuses on foods such as fruit, vegetables, legumes and nuts, while the reversed Empirical Dietary Inflammatory Index assesses the overall anti-inflammatory quality of someone’s diet.

Scientists also analysed blood samples for three key markers linked to dementia risk.

These included p-tau217, which is strongly associated with Alzheimer’s disease, neurofilament light chain (a marker of nerve cell damage), and glial fibrillary acidic protein, which is linked to inflammation or injury in the brain.

By the end of the study, 240 participants had developed dementia.

After accounting for factors such as age, sex, education, smoking, exercise, weight, calorie intake and existing health problems, researchers found that better diet quality was linked to a lower risk of the disease.

The clearest results were seen for the lower-inflammatory diet.

Among people with raised levels of Alzheimer’s and brain damage markers, stronger adherence to this diet was consistently linked to a reduced risk of dementia.

Even those already showing biological red flags for dementia appeared to keep the disease at bay for longer if they ate a healthier diet. 

However, because the study was observational, it can only show a link rather than prove that a healthier diet directly prevents dementia or delays its onset. 

Inflammation is increasingly being linked to a wide range of illnesses and diseases.

Usually, it is part of the body’s natural defence system.

When the immune system detects an infection or injury, it sends defensive cells rushing to the affected area. This can trigger familiar signs such as heat, swelling and redness, or a fever when the whole body is involved.

But scientists now know inflammation is not only caused by infections, it can be triggered by other health problems that keep the immune system in a state of low-level activation, including obesity, poor diet and long-term health problems.

This chronic inflammation is thought to damage brain cells, fuel the build-up of Alzheimer’s-related proteins and speed up the processes that can lead to dementia. 

The authors of the new study say the findings support further research into personalised dietary advice for people at higher dementia risk.

There are an estimated one million people in the UK living with dementia – and by 2040 that figure is expected to climb to 1.4 million. 

But while the search for a cure continues, there is mounting evidence that prevention may be the best form of defence for now.

A major consensus earlier this year by world-leading experts, building on The Lancet Commission on Dementia, concluded that almost half of all cases globally could be prevented, or at least delayed for several years if action was taken to address 14 risk factors. 

These range from smoking and excess alcohol consumption, to loneliness and a sedentary lifestyle.