Do interaction and joint effects between physical activity and dietary inflammatory index modify stroke risk?

Stroke is a major public health threat, and both physical activity (PA) and diet are modifiable risk factors for stroke. This study assessed the interaction and joint effects of PA and the dietary inflammatory index (DII) on stroke.

We included 18,676 participants from the 2007-2020 National Health and Nutrition Examination Survey. The independent associations, interactions, and joint effects of PA and the DII on stroke were assessed by weighted multivariable logistic regression.

The weighted mean age of the participants was 48.24 years, and comprised 703 individuals who had experienced a stroke. After adjusting for confounders, increased stroke risk was independently associated with a higher DII (Q4, odds ratio [OR]: 1.72, 95 % confidence interval [CI]: 1.27-2.34) and insufficient PA (inactive, OR: 1.37, 95 % CI: 1.05-1.78). No significant multiplicative (OR: 1.11, 95 % CI: 0.34-1.93) or additive (relative excess risk due to interaction: 0.45, 95 % CI: 0.35-1.25) interactions were found between DII and PA. The results of joint associations indicated that individuals who consumed the most pro-inflammatory diet (DII, Q4) and were physically inactive (OR: 2.39, 95 % CI: 1.61-3.56) had the highest stroke risk than those who consumed the most anti-inflammatory diet (DII, Q1) and were physically active.

Active PA and low DII scores are independent protective factors against stroke. Although the multiplicative and additive effects of the DII and PA on stroke risk are not statistically significant, the analysis of their joint effects suggest that individuals who consume anti-inflammatory diets and exhibit active PA consistently have the lowest risk of stroke.