Effects of omega-3 PUFA-enriched egg consumption on metabolic parameters in elderly adults with metabolic syndrome: study protocol for a randomized controlled trial.

Background: Metabolic syndrome (MetS) affects approximately one-third of community-dwelling older adults (≥65 years) and is characterized by concurrent dysregulation of glucose and lipid metabolism alongside chronic low-grade inflammation. Poor long-term adherence to conventional omega-3 supplementation has prompted interest in sustainable, food-based delivery systems. Omega-3 polyunsaturated fatty acid (PUFA)-enriched eggs-produced through dietary modification of hen feed to enhance eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content-represent a palatable and easily incorporated dietary vehicle for sustained intervention. Methods: This is a three-arm, parallel-group randomized controlled trial that will enroll 180 community-dwelling adults aged ≥ 65 years with MetS. Participants will be randomly allocated (1:1:1) to receive either omega-3 PUFA-enriched eggs, regular eggs, or no egg intervention (usual diet) for 12 weeks. Those assigned to the egg intervention groups will consume one boiled egg daily, five days per week. The control group will maintain their habitual dietary patterns without additional egg consumption. Biological samples (blood, urine, and stool) will be collected at baseline and weeks 4, 8, and 12. Plasma concentrations of omega-3 fatty acids, lipid metabolism indicators,inflammation and oxidative stress markers will be measured. Exploratory outcomes include comprehensive multi-omics profiling, encompassing metabolomics and gut microbiome will be tested. Results: The primary outcome will be the longitudinal changes in fasting triglycerides (TG) measured at Weeks 0, 4, 8, and 12, with comparisons between the omega-3 PUFA-enriched eggs group and the regular eggs control group. Secondary outcomes will include glucose levels, insulin concentrations, lipid profiles, as well as biomarkers of inflammation and oxidative stress. Integrative multi-omics analyses will be conducted to explore the pathways linking omega-3 PUFA-enriched eggs consumption to alterations in metabolomic features and gut microbiota. Conclusions: This trial will aim to assess the efficacy, feasibility, and mechanisms of omega-3 PUFA-enriched eggs in elderly adults with MetS, so as to provide insights and evidence to support scalable community-based dietary interventions. Trial registration: The protocol has been registered on the website of Chinese Clinical Trial Registry. The Identifier code is ChiCTR2600120125. The Registry date is 10 March, 2026. Registry name is "Interventional Effect of ω-3 Polyunsaturated Fatty Acid-Fortified Eggs on Elderly Patients with Metabolic Syndrome." Registration URL is [https://www.chictr.org.cn/bin/userProject].