Impact of dietary cholesterol from eggs and saturated fat on LDL cholesterol levels: a randomized cross-over study

Abstract

Background: Cardiovascular disease (CVD) remains a leading cause of death. Although dietary cholesterol from eggs has been a focus of dietary guidelines, recent evidence suggests that saturated fat has a greater impact on LDL cholesterol.

Objectives: This study examined the independent effects of dietary cholesterol and saturated fat on LDL concentrations.

Methods: In this randomized, controlled, cross-over study (clinicaltrials.gov, NCT05267522), 61 adults (age 39 ± 12 y, BMI 25.8 ± 5.9 kg/m²) with baseline LDL cholesterol <3.5 mmol/L (135.3 μg/dL) were assigned to 3 isocaloric diets for 5 wk each: high-cholesterol (600 mg/d), low-saturated fat (6%) including 2 eggs/d (EGG); low-cholesterol (300 mg/d), high-saturated fat (12%) without eggs (EGG-FREE); and a high-cholesterol (600 mg/d), high-saturated fat (12%) control diet (CON) including 1 egg/wk. Outcomes were assessed at the end of each diet phase.

Results: Fifty-four participants completed ≥1 diet phase, and 48 completed all diet phases. Compared with CON, EGG but not EGG-FREE reduced LDL cholesterol (CON 109.3 ± 3.1 μg/dL compared with EGG 103.6 ± 3.1 μg/dL P = 0.02 compared with EGG-FREE 107.7 ± 3.1 μg/dL, P = 0.52). Across all diets, saturated fat intake was positively correlated with LDL cholesterol (β = 0.35, P = 0.002), whereas dietary cholesterol was not (β = -0.006, P = 0.42). Compared with CON, EGG but not EGG-FREE reduced concentrations of large (EGG β = -48.6, P = 0.03; EGG-FREE β = -35.85, P = 0.12) and increased concentrations of small LDL particles (EGG β = 95.1, P = 0.004; EGG-FREE β = 55.82, P = 0.10).

Conclusions: Saturated fat, not dietary cholesterol, elevates LDL cholesterol. Compared with consuming a high-saturated fat diet with only 1 egg/wk, consuming 2 eggs daily as part of a low-saturated fat diet lowers LDL concentrations, which may reduce CVD risk. However, this effect on CVD risk may be mitigated, at least in part, by a reduction in less-atherogenic large LDL particles and an increase in more atherogenic small LDL particles.

Trial registration: This trial was registered at clinicaltrials.gov as NCT05267522 (https://clinicaltrials.gov/study/NCT05267522?term=eggs%20and%20cholesterol&rank=3).

Keywords: LDL particle size; cholesterol; eggs; lipids and lipoproteins; saturated fat.