Association between egg consumption and cognitive function among Chinese adults: long-term effect and interaction effect of iron intake.

The association between egg consumption and cognitive function is inclusive. We aimed to assess the association between egg consumption and cognitive function in Chinese adults and tested the interaction between egg consumption and iron intake. The data used was from a nationwide sample (n = 4852, age ≥55 years) from the China Health and Nutrition Survey between 1991 and 2006. Assessment of cognitive function was conducted in 1997, 2000, 2004, and 2006. Dietary egg intake was obtained by 24-hr dietary recalls of 3 consecutive days during home visits between 1991 and 2006. Multivariable mixed linear regression and logistic regression were used. Egg intake was positively associated with global cognitive function. In fully adjusted models, across the quartiles of egg intake the regression coefficients (95% CIs) were 0, 0.11 (-0.28-0.51), 0.79 (0.36-1.22) and 0.92 (0.43-1.41), respectively. There was a significant interaction between egg intake and iron intake. The association between high egg intake and cognitive function was stronger among those with low iron intake than those with high iron intake. In addition, there was a significant interaction between egg consumption and gender, with the association mainly observed in women but not men. Furthermore, compared with non-consumers, those with higher egg consumption (Q4) had the odds ratio (and 95% CI) of 0.93 (0.74-1.19), 0.84 (0.69-1.02) for self-reported poor memory and self-reported memory decline, respectively. Higher egg intake is associated with better cognition in Chinese adults among those with low iron intake.