Egg and Dietary Cholesterol Consumption and the Prevalence of Metabolic Syndrome: Findings from a Population-Based Nationwide Cohort

Abstract

Background: Although the Chinese Dietary Guidelines (2016) removed restrictions on dietary cholesterol intake, evidence of egg and dietary cholesterol intake and cardiometabolic diseases is inconsistent. Associations between egg and cholesterol consumption and metabolic syndrome (MetS) in non-Western populations are still poorly documented.

Objective: Our aim was to assess egg and dietary cholesterol intake in relation to the prevalence of MetS among participants in a Chinese nationwide study.

Design: This cross-sectional study used data from the China Health and Nutrition Survey (1991-2009).

Participants/setting: The sample consisted of 8,241 healthy Chinese adults (20 years and older).

Main outcome measures: MetS cases were defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria.

Statistical analysis: Cumulative means of egg and cholesterol consumption were calculated in accordance with 3 consecutive 24-hour dietary recalls in each examination cycle. Logistic regression models were conducted to assess the associations with prevalent MetS.

Results: Overall, 2,580 (31.3%) participants were identified as MetS cases in 2009. After multivariate adjustment, total egg consumption (>1 egg/d) was associated with 20% higher odds of MetS (odds ratio [OR] 1.20, 95% CI 1.06 to 1.37; P trend = .001) compared with consumption of ≤1/2 egg/d. Examining cooking methods, a positive association was observed between fried egg consumption and MetS odds (OR comparing the highest category [>1/2 egg/d] with the lowest category [≤1/7 egg/d] 1.22, 95% CI 1.08 to 1.39; P trend = .001), and nonfried egg intake was not associated with MetS odds (P trend = .08). Total dietary intake and egg-sourced cholesterol intake were both positively correlated with MetS odds (OR 1.31, 95% CI 1.12 to 1.53; P trend = .005) comparing the highest consumption (>371 mg · 2,000 kcal^-1 · d^-1) with the lowest consumption (≤132 mg · 2,000 kcal^-1 · d^-1) for total dietary cholesterol (OR 1.36; 95% CI 1.17 to 1.58; P trend < .001) and comparing the highest consumption (>232 mg · 2,000 kcal^-1 · d^-1) with the lowest consumption (≤46 mg · 2,000 kcal^-1 · d^-1) for egg-sourced cholesterol; similar associations were not observed for non-egg-sourced cholesterol consumption (P trend = .83). Substituting eggs and fried eggs for other protein sources, including low-fat and whole-fat dairy products; nuts and legumes; total red meat; processed meat; poultry meat; or seafood, was still associated with higher odds of MetS.

Conclusions: Consumption of >1 egg/d and >1/2 fried egg/d was associated with a higher prevalence of MetS than consumption of ≤1/2 egg/d and ≤1/7 fried egg/d. Future longitudinal cohort studies and randomized controlled trials are needed to further investigate the relationship between egg consumption and MetS and explore possible mechanisms of action.

Trial registration: ClinicalTrials.gov NCT04104308.

Keywords: Cholesterol; Eggs; Fried eggs; Metabolic syndrome; Nonfried eggs.