Switching from an unhealthy to a healthy diet in middle age could potentially add almost a decade to a person's life, suggests a new study published in Nature Food.

The study used a model to estimate how lifestyle changes might impact life expectancy, analysing data from 467,354 participants in the UK Biobank.

The results indicated that people in their 40s who transitioned from an unhealthy diet to a longevity-associated diet could gain around 10 years of life expectancy.

The study emphasized that the earlier dietary improvements were initiated, the more significant the gains in life expectancy, with whole grains, nuts, and fruits playing a crucial role.

The University of Bergen in Norway and the University of Glasgow in Scotland conducted the research, highlighting that a longevity-associated diet includes high intake of milk, dairy, vegetables, nuts, and legumes, along with moderate intake of whole grains, fruit, fish, and white meat.

It also features a relatively low intake of eggs, red meat, and sugar-sweetened beverages, as well as limited consumption of refined grains and processed meat.

This dietary pattern aligns with the Mediterranean diet, known for promoting overall health by emphasizing whole foods and restricting processed and sugary items.

The study pointed out that whole grains, nuts, and fruits were associated with the most significant life expectancy gains, while sugar-sweetened beverages and processed meat were linked to higher mortality rates.

The researchers acknowledged that their findings demonstrated correlation, not causation, and adjusted their model to account for factors like smoking and socioeconomic status.

However, they noted that the UK Biobank did not measure rice consumption, an essential dietary component for many migrant groups, and recognized the potential fluctuation of dietary patterns over time as a limitation.

Professor Gunter Kunhle, a nutritional scientist at the University of Reading, emphasized the findings' alignment with existing evidence about diets contributing to longer, healthier lives.

He also highlighted the importance of promoting a healthy, balanced diet throughout life, even though transitioning from decades of an unhealthy diet to a balanced one can be challenging.