Combined associations of physical activity, diet quality and their changes over time with mortality: findings from the EPIC-Norfolk study, United Kingdom.
BMC medicine 2024 ; 22: 464.
Aryannezhad S, Mok A, Imamura F, Wareham NJ, Brage S, Forouhi NG
DOI : 10.1186/s12916-024-03668-6
PubMed ID : 39402526
PMCID : PMC11476187
URL : https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-024-03668-6
Abstract
Physical activity (PA) and diet quality have each been shown to be inversely associated with mortality but their combined impact on longevity has been less explored, particularly when considering their changes over time. This study aimed to examine the separate and combined associations of PA, diet quality and their changes over time with mortality outcomes.
A prospective cohort study was performed on 9349 adults aged 40 to 79 years from the population-based European Prospective Investigation into Cancer in Norfolk Study, with repeated measurements of PA and diet (from 1993 till 2004) and subsequent follow-up till 2022 (median follow-up 18.8 years). Validated questionnaires were used to derive physical activity energy expenditure (PAEE) as a proxy of total PA and adherence to the Mediterranean diet score (MDS, range 0-15 points) as an indicator of overall diet quality, and their changes over time (∆PAEE and ∆MDS). Cox regression models adjusted for potential confounders and mediators were used to estimate hazard ratios (HRs) and 95% CIs.
Over 149,681 person-years of follow-up, there were 3534 deaths. In adjusted models, for each 1-SD difference in baseline PAEE (4.64 kJ/kg/day), ∆PAEE (0.65 kJ/kg/day per year), baseline MDS (1.30 points) and ∆MDS (0.32 points per year), HRs (95% CI) for all-cause mortality were 0.90 (0.86 to 0.94), 0.89 (0.85 to 0.93), 0.95 (0.91 to 0.99) and 0.93 (0.90 to 0.97), respectively. Compared with participants with sustained low PAEE (< 5 kJ/kg/day) and low MDS (< 8.5 points), those with sustained high PAEE and high MDS had lower all-cause mortality (HR 0.78; 95% CI: 0.68-0.91), as did those who improved both PAEE and MDS (0.60; 0.44-0.82). There was no evidence of interaction between PA and diet quality exposures on mortality risk. Population impact estimates suggested that if all participants had maintained high levels of PA and diet quality consistently, cumulative adjusted mortality rate would have been 8.8% (95% CI: 2.4 to 15.3%) lower.
These findings suggest that adopting and maintaining higher levels of PA and diet quality are associated with lower mortality. Significant public health benefits could be realised by enabling active living and healthy eating through adulthood.
Lay Summary
It has been well known for some time that physical activity and a good quality diet, when examined separately, are important for our health. Less is known about different combinations of activity and diet and what happens when we look at how they change over time. In fact, claims have been made that one is more important than the other and even play them off against each other, suggesting you could outrun a bad diet or eat vegetables to avoid the consequences of being a couch potato. Therefore, our study aimed to explore how changes in physical activity and diet quality, separately and together, relate to longevity.
We did our research in 9,349 women and men from Norfolk, UK, who were aged 40 to 79 years old when first enrolled between 1993 and 1997. We followed them up for almost three decades to see how their health behaviours influenced their life span. Participants reported their physical activity and diet quality repeatedly between 1993 and 2004. We tracked how these health behaviours changed and analysed their impact on death until 2022.
We found that both starting off being physically active and eating a high-quality diet, as well as improving these two habits over time, were linked to a lower risk of death. Regardless of the starting point, even small improvements in activity or diet quality were linked to longer life. The greatest benefits were seen when both healthy habits were combined, rather than focusing on optimising one of the two while neglecting the other. Assuming that health behaviours and longevity have a cause-and-effect relationship, 9% of deaths in this population could have been prevented if everyone had sustained improved levels of both physical activity and diet throughout the assessment period.
In summary, encouraging both physical activity and healthy eating throughout adulthood, rather than improving one at the expense of the other, is associated with living longer. Moreover, even if someone has not adopted healthy behaviours until mid-to-late adulthood, it is still not too late to embrace a healthier lifestyle to enhance longevity.