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Fast Food Diet Ages Young Adults Faster Than Their Years, Twin Study Reveals

A study of young adult twins has revealed that poor dietary choices can accelerate biological aging even before reaching 25, with fast food and processed meat consumption potentially making people biologically older than their actual age.

The research, published in Clinical Nutrition, demonstrates that what young adults eat may influence how quickly their bodies age at the cellular level, independent of their chronological age. The study utilized advanced epigenetic analysis to measure biological aging in 826 twins aged 21-25.

“Some of the observed associations may also be explained by other lifestyle factors, such as physical activity, smoking, and body weight, as healthy and unhealthy lifestyle habits tend to cluster in the same individuals,” explains postdoctoral researcher Suvi Ravi from the University of Jyväskylä. “However, diet maintained a small independent association with aging even when we accounted for other lifestyle factors.”

The researchers identified six distinct dietary patterns among participants. Those following diets high in fast food, processed meat, and sugar-sweetened beverages while low in fruits and vegetables showed accelerated biological aging. In contrast, individuals whose diets emphasized plant-based foods and limited meat consumption displayed slower aging markers.

By studying twins, the research team gained unique insights into how genetics influence the relationship between diet and aging. The findings suggest that shared genetic background, rather than shared childhood environment, explains some of the connection between dietary choices and biological aging in young adulthood.

The study utilized sophisticated epigenetic clocks – computational models that assess biological age based on chemical modifications to DNA – to measure aging rates. These modifications, known as methyl groups, can regulate gene expression and serve as markers of biological age.

The implications extend beyond just feeling old. Accelerated biological aging has been linked to increased risks of various diseases and mortality. The research suggests that dietary choices made in young adulthood could have lasting impacts on health trajectories.

The investigation was part of the broader FinnTwin12 study, examining 363 twin pairs. Participants completed detailed food frequency questionnaires covering 55 different food items, providing researchers with comprehensive dietary data.

The findings highlight a critical window for intervention in young adulthood. While previous research has focused on middle-aged and older adults, this study demonstrates that the biological impacts of poor dietary choices begin accumulating much earlier.

“This doesn’t mean that a health-promoting diet would not benefit everyone,” Ravi emphasizes, suggesting that despite genetic influences, dietary improvements could benefit all young adults regardless of their genetic predisposition.

The research was conducted as part of the “The role of nutrition in the prevention of common diseases” project, funded by the Juho Vainio Foundation. The study team is part of the GenActive research group, which investigates genetic and lifestyle factors influencing biological aging, health, and functional capacity under the leadership of Associate Professor Elina Sillanpää.

As young adults increasingly rely on convenience foods and fast-food options, these findings provide compelling evidence for the importance of establishing healthy dietary patterns early in life. The research suggests that what we eat in our twenties isn’t just about immediate health effects – it’s literally aging us at the cellular level.


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