Eggs, selected egg-rich nutrients, and non-alcoholic fatty liver disease in the Framingham Heart Study

Authors: YIANNAKOU, IONNA - Boston University; LONG, MICHELLE - Boston University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BEISER, ALEXA - Boston University; PICKERING, RICHARD - Boston University; MOORE, LYNN - Boston University

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2024
Publication Date: 10/15/2024
Citation: Yiannakou, I., Long, M., Jacques, P.F., Beiser, A., Pickering, R.T., Moore, L.L. 2024. Eggs, selected egg-rich nutrients, and non-alcoholic fatty liver disease in the Framingham Heart Study. Journal of Nutrition. https://doi.org/10.1016/j.tjnut.2024.10.026.
DOI: https://doi.org/10.1016/j.tjnut.2024.10.026

Interpretive Summary: Eggs are a nutrient-dense food. However, eggs have been historically considered less healthy due to their dietary cholesterol content, which was thought to increase risk of cardiovascular disease and other disorders, including non-alcoholic fatty liver disease (NAFLD). Current dietary guidance recommends egg consumption within the context of heart-healthy patterns, but evidence on the association between eggs or egg-rich nutrients and NAFLD is limited and inconsistent. Given uncertainty about this relationship, we examined the association between intakes of eggs and selected egg-rich nutrients on NAFLD risk in approximately 1,700 middle-aged and older adults. This study suggests that consuming 2 or more eggs per week was not adversely associated with the development of NAFLD, but higher dietary choline intakes were strongly associated with a lower NAFLD risk. Nonetheless, eggs are an inexpensive source of several important nutrients, and the current findings support their inclusion in a healthy diet pattern.

Technical Abstract: Eggs are rich in bioactive compounds, including choline and carotenoids, that may benefit cardiometabolic outcomes. However, little is known about their relation with nonalcoholic fatty liver disease (NAFLD). We investigated the association between intakes of eggs and selected egg-rich nutrients (choline, lutein and zeaxanthin) and NAFLD risk and changes in liver fat over approximately 6 years of follow-up in the Framingham Offspring and Third Generation cohorts. On two separate occasions (2002-2005 and 2008-2011), liver fat was assessed using a computed tomography scan to estimate the average liver fat attenuation relative to a control phantom to create the liver phantom ratio (LPR). In 2008-2011, cases of incident NAFLD were identified as an LPR =0.33 in the absence of heavy alcohol use, after excluding prevalent NAFLD (LPR =0.33) in 2002-2005. Food frequency questionnaires were used to estimate egg intakes (classified as <1, 1, and =2 per week) and dietary choline (adjusted for body weight using the residual method), and the combined intakes of lutein and zeaxanthin. Multivariable modified Poisson regression and general linear models were used to compute incident risk ratios (RR) of NAFLD and adjusted mean annualized liver fat change. NAFLD cumulative incidence was 19% among a total of 1414 participants. We observed no associations between egg intake or the combined intakes of lutein and zeaxanthin with an incident NAFLD risk or liver fat change. Other diet and cardiometabolic risk factors did not modify this association. However, dietary choline intakes were inversely associated with NAFLD risk (RR for tertile 3 vs. 1: 0.69, 95% CI: 0.51-0.94). While egg intake was not directly associated with NAFLD risk, eggs are a major source of dietary choline, which was strongly inversely associated with NAFLD risk in this community-based cohort.