A healthy diet in one particular decade can help prevent dementia

Eating a healthy diet at the age of 43 has been found to keep your brain functioning well and reduce the risk of dementia later in life. 

But that doesn’t mean you only have to eat well for one year.

A new study following people and their diets over decades found that what they ate at 43 had a significant impact on memory decline in later life. Until now, studies on dementia have mainly focused on the eating habits of people in their 60s and 70s.

The research looked at data from 3,059 UK adults who were born in 1946 and have been tracked for more than 75 years as part of a national research project. 

The participants completed food diaries at different ages to provide a snapshot of their diets, which were rated as ‘low’, ‘moderate’ or ‘high’ quality based on factors including how many vegetables or sugary foods they ate. 

They also completed regular cognitive tests that measured their brain function and memory between the ages of 4 and 63.

Participants were then divided into groups based on their performance, which showed a strong link to diet.

However, one specific age, 43, proved to be the strongest predictor of dementia risk in later life. Better quality diets at that age resulted in a lower risk of cognitive decline, and every small increase in quality from this age reduced the risk of a lower brain function by 4%.

Lead author Dr Kelly Cara said: ‘Dietary patterns that are high in whole or less processed plant-food groups including leafy green vegetables, beans, whole fruits and whole grains may be most protective.

‘Adjusting one’s dietary intake at any age to incorporate more of these foods and to align more closely with current dietary recommendations is likely to improve our health in many ways, including our cognitive health.’

For example, the results revealed that only around 8% of people with low-quality diets sustained high cognitive ability, while about 7% of people with high-quality diets sustained low cognitive ability over time, compared with their peers.

The findings were presented at the Nutrition 2024 conference.

The team added: ‘Our results suggest dietary patterns in midlife, before age 50, may be most predictive of cognitive trends up to age 69.’

Dr Kelly Cara said: ‘These initial findings generally support current public health guidance that it is important to establish healthy dietary patterns early in life in order to support and maintain health throughout life.

‘Our findings also provide new evidence suggesting that improvements to dietary patterns up to midlife may influence cognitive performance and help mitigate, or lessen, cognitive decline in later years.’

The researchers added that even slight differences in diet quality in childhood appeared to set the tone for later life diet – for better or for worse.