The association between physical activity and dietary inflammatory index on mortality risk in U.S. adults

ABSTRACT

Objective: Both diet and physical activity have been shown to be associated with reduced risk for mortality. The current study examined the individual and combined effects of the inflammatory quality of diet and physical activity levels on mortality risk.

Methods: Data from the 1999–2004 National Health and Nutrition Examination Survey were used (N = 10,610 adults 20–85 years). Participants were followed through 2011, entailing a median follow-up time of 9.6 yrs. Dietary patterns were assessed using the Dietary Inflammatory Index (DII®), with a higher score indicative of greater diet-related inflammation. Habitual physical activity was assessed via a 30-day recall of leisure-time physical activity as well as objectively via up to seven days of accelerometry assessment. Four lifestyle groups were created: 1) unfavorable DII and inactive (referent); 2) unfavorable DII and active; 3) favorable DII and inactive; and 4) favorable DII and active.

Results: Those who had a low DII score (favorable) and who self-reported being active had a 39% reduced hazard of all-cause mortality (HR = 0.61; 95% CI: 0.49–0.76) when compared to those with a higher DII and were inactive. Results based on accelerometer-assessed physical activity indicate a 65% reduced hazard (HR = 0.35; 95% CI: 0.17–0.74). DII and physical activity also were individually associated with mortality in the expected direction. Specifically, DII was positively associated (HR = 1.08; 95% CI: 1.04–1.13) and physical activity inversely associated (HR = 0.97; 95% CI: 0.94–0.99) with all-cause mortality risk.

Conclusion: The combination of consuming a more anti-inflammatory diet and having adequate levels of physical activity is associated with a reduced risk of mortality. Additional replicative work is warranted.

KEYWORDS:

• Accelerometry
• chronic inflammation
• diet
• epidemiology
• exercise
• NHANES
• survival

Declaration of interest

JH owns controlling interest in Connecting Health Innovations LLC (CHI), a company planning to license the right to his invention of the dietary inflammatory index (DII) from the University of South Carolina in order to develop computer and smart phone applications for patient counseling and dietary intervention in clinical settings. MW and NS are employees of CHI. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Additional information

Funding

MW, NS, and JH were supported by grant number R44DK103377 from NIH’s National Institute of Diabetes and Digestive and Kidney Diseases.