Ultra-processed foods are making us old beyond our years

In recent years, ultra-processed food (UPFs) consumption has surged globally, raising concerns about its impact on health.

Ultra-processed foods are industrial formulations typically containing ingredients not commonly used in home cooking, such as hydrogenated oils, high-fructose corn syrup, flavour enhancers, and emulsifiers. Examples of these types of foods include chips, soft drinks, instant noodles, ice cream, chocolate, biscuits, ready-to-eat meals, sausages, burgers, chicken and fish nuggets, sweet or savoury packaged snacks, and energy bars.

These foods, and the ingredients they contain, are designed for convenience and long shelf life, and to enhance palatability, but often come at the cost of nutritional value.

Now, a groundbreaking study, led by Monash University, has shed light on a particularly alarming consequence – the acceleration of biological ageing.

Biological age refers to how old a person seems based on various molecular biomarkers, compared to chronological age, which is the number of years a person has lived.

A person’s biological age is a relatively new way of measuring a person’s health, and can be traced back to 2013, when geneticist Steve Horvath developed the epigenetic clock, which measures DNA methylation levels. DNA methylation is a process that modifies the function of genes.

A second generation of epigenetic clocks was developed a few years later that incorporated environmental variants such as smoking or chronological age. Among these was the PhenoAge and GrimAge clocks.

As well as diet, biological age can be influenced by genetics, general lifestyle, and environmental factors, and it can differ significantly from chronological age.

A person with a healthy lifestyle may have a biological age younger than their chronological age, while poor lifestyle choices, such as a diet high in UPFs, can accelerate biological ageing.

The Monash University study, published in the journal Age and Ageing, was led by nutritional biochemist Dr Barbara Cardoso, a senior lecturer in the University’s Department of Nutrition, Dietetics and Food. It involved 16,055 participants from the United States aged 20-79, whose health and lifestyles were comparable to those in other Western countries such as Australia. The study used the PhenoAge clock to assess biological ageing.

It found a significant association between increased UPF consumption and accelerated biological ageing. For every 10% increase in UPF consumption, the gap between biological and chronological age widened by approximately 2.4 months.

Participants in the highest UPF consumption quintile (68-100% of energy intake in their diet) were biologically 0.86 years older than those in the lowest quintile (39% or less of energy intake in their diet).

Dr Cardoso said the findings underlined the importance of eating as many unprocessed and minimally-processed foods as possible.

“The significance of our findings is tremendous, as our predictions show that for every 10% increase in total energy intake from ultra-processed food consumption there is a nearly 2% increased risk of mortality and 0.5% risk of chronic disease over two years,” she said.

“Assuming a standard diet of 2000 calories [8500 kilojoules] per day, adding an extra 200 calories of ultra-processed food, which roughly equals an 80-gram serving of chicken bites or a small chocolate bar, could lead to the biological ageing process advancing by more than two months compared to chronological ageing.”

Read more Is greenery the secret to slowing the biological ageing process?

The study used data from the US National Health and Nutrition Examination Survey (NHANES) 2003-2010. Diet quality was assessed with the American Heart Association (AHA) 2020 and the Healthy Eating Index 2015 (HEI-15).

The association between UPF intake and biological ageing remained significant after adjusting for diet quality and total energy intake, using the above data as a baseline.

This suggested the association could be due to other factors such as lower intake of flavonoids or phytoestrogens, which occur in natural foods such as fresh fruit and vegetables, or higher exposure to packaging chemicals and compounds formed during food processing.

“Adults with higher UPF tended to be biologically older,” the study found. “This association is partly independent of diet quality, suggesting that food processing may contribute to biological ageing acceleration. Our findings point to a compelling reason to target UPF consumption to promote healthier ageing.”

The results also support earlier research linking UPF consumption to ageing markers such as telomere length (a shorter telomere length is a sign of cell ageing), frailty, cognitive decline, and dementia. 

Dr Cardoso said while the study participants were from the US, the relevance of the findings apply to Australians too – on average, ultra-processed foods represented almost 40% of total energy intake among Australian adults.

She said given the global population continued to age, demonstrating the adverse effects of UPFs reinforced the need for dietary-focused public health strategies to prolong a healthy lifespan.

“Our findings indicate that reducing ultra-processed foods in the diet may help slow the biological ageing trajectory, bringing another reason to target ultra-processed foods when considering strategies to promote healthy ageing,” she said.

Mechanisms behind UPFs and ageing

Mechanisms by which UPFs may accelerate biological ageing include:

1. Nutrient deficiency: UPFs are often low in essential nutrients such as vitamins, minerals, and antioxidants, which are crucial for maintaining cellular health and preventing oxidative stress.
2. Chemical additives: Many UPFs contain artificial additives and preservatives that may have adverse effects on health, including promoting inflammation and disrupting metabolic processes.
3. Packaging chemicals: Exposure to chemicals from food packaging, such as bisphenol A (BPA), has been linked to various health issues, including accelerated ageing.

Practical steps to reduce UPF intake

To mitigate the adverse effects of UPFs, individuals can take several practical steps:

1. Increase whole foods: Emphasise whole, minimally processed foods such as fruits, vegetables, whole grains, nuts, and seeds in your diet.
2. Read labels: Be mindful of food labels and avoid products with long lists of unfamiliar ingredients.
3. Cook at home: Preparing meals at home allows for greater control over ingredients and cooking methods.
4. Limit convenience foods: Reduce reliance on ready-to-eat meals and snacks, opting instead for healthier alternatives.

This work was carried out in collaboration with senior author Euridice Martinez Steele, from the University of Sao Paulo (Brazil), Daniel Belsky, from Columbia University (US), Dayoon Kwon, from the University of California at Los Angeles, Priscila Machado, from Deakin University, and Junxiu Liu, from Icahn School of Medicine at Mount Sinai (US).