Independent Effects of High-cholesterol (High-egg) and High-saturated Fat Diets on LDL-cholesterol

NCT ID: NCT05267522

Last Updated: 2023-12-13

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 77 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2022-03-01
• Study Completion Date: 2023-08-31

Brief Summary

This study will comprise a randomized controlled, counter-balanced, cross-over trial to evaluate the independent effects of a high cholesterol (high egg), low saturated fat diet and a high saturated fat, low cholesterol diet on blood lipids. Evaluations also include analysis of physical activity as there is emerging evidence that the lutein and zeaxanthin in egg yolk may increase physical activity levels by crossing the blood-brain barrier and altering neuronal function. The study will also investigate effects on a number of novel lipoprotein parameters (particle size and particle concentrations).

Detailed Description

Eggs are high in cholesterol but low in saturated fat. Data from cross-sectional, prospective, and randomized controlled trials (RCTs), suggest that egg intake does not adversely affect blood lipids or increase cardiovascular disease (CVD) risk. In fact, there is some evidence that egg consumption may reduce CVD risk. However, to date there has been no direct comparison of the effects of a high cholesterol (high egg), low saturated fat diet and a low cholesterol, high-saturated fat diet on blood lipids, and no studies have accounted for potential effects of differences in physical activity, which can also influence the blood lipid profile. Evaluations of the effect of egg consumption on blood lipids should include analysis of physical activity as there is emerging evidence that the lutein and zeaxanthin in egg yolk may increase physical activity levels by crossing the blood-brain barrier and altering neuronal function. We will directly compare the effects of a high cholesterol, low saturated fat diet and a low cholesterol, high saturated fat diet on blood lipids, using egg consumption to manipulate dietary cholesterol intake, while also accounting for physical activity levels. The study will investigate effects on a number of novel lipoprotein parameters (particle size and particle concentrations).

Conditions

Hypercholesterolemia; Hyperlipidemias; Physical Inactivity; Diet, Healthy

Keywords

Cholesterol; Eggs; Saturated Fat; Low density lipoprotein cholesterol; lutein; physical activity

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Egg Diet

Egg diet, contains 2 eggs per day and limits saturated fat to 6% of energy intake. Cholesterol intake is 600mg/day. Protein and carbohydrate levels will be maintained at 20% and 40% of energy intake, respectively. This diet will be followed for 5 weeks.

Group Type: EXPERIMENTAL

Egg diet

Intervention Type: OTHER

30% fat \[6% saturated fat\], 20% protein, 40% carbohydrate, 600 mg cholesterol

Egg-free Diet

Egg-free diet, limits cholesterol to 300 mg/day (no eggs) with saturated fat intake at 12% of energy intake. Protein and carbohydrate levels will be maintained at 25% and 40% of energy intake, respectively. This diet will be followed for 5 weeks.

Group Type: ACTIVE_COMPARATOR

Egg-free Diet

Intervention Type: OTHER

30% fat \[12% saturated fat\], 25% protein, 40% carbohydrate, 300 mg cholesterol

Control Diet

Comparator diet based on the average Australian diet, limited to 1 egg per week, with saturated fat intake at 12% of energy intake. Cholesterol intake is 600 mg/day. Protein and carbohydrate levels will be maintained at 25% and 40% of energy intake, respectively. This diet will be followed for 5 weeks.

Group Type: ACTIVE_COMPARATOR

Control Diet

Intervention Type: OTHER

30% fat \[12% saturated fat\], 25% protein, 40% carbohydrate, 600 mg cholesterol

Interventions

Egg diet

30% fat \[6% saturated fat\], 20% protein, 40% carbohydrate, 600 mg cholesterol

Intervention Type: OTHER

Egg-free Diet

30% fat \[12% saturated fat\], 25% protein, 40% carbohydrate, 300 mg cholesterol

Intervention Type: OTHER

Control Diet

30% fat \[12% saturated fat\], 25% protein, 40% carbohydrate, 600 mg cholesterol

Intervention Type: OTHER

Other Intervention Names

High cholesterol + low saturated fat diet; Low cholesterol + high saturated fat diet; Average Australian Diet

Eligibility Criteria

Inclusion Criteria

• Male or female, aged 18 - 60 years
• Blood LDL-C <3.5 mmol/L (measured at screening using an automated analyser (Cholestech LDX System).
• Non-smoker (or other nicotine products) (minimum 6 months).

Exclusion Criteria

• Have diagnosed cardiovascular disease (including uncontrolled high blood pressure) or a chronic disease, including Type-1 or -2 diabetes, kidney or liver disease, gastrointestinal disorders requiring medical nutrition therapy (e.g., Crohn's disease, irritable bowel, coeliac disease) or any other condition that may have an impact on study outcomes.
• Have allergies or strong aversion to eggs or other components of the test foods (diets are not suitable for vegetarians).
• Consume more than 5 eggs per week in the month prior to beginning the trial.
• Participant has a recent history (within 12 months) or strong potential for alcohol abuse. Defined as >14 standard drinks per week.
• Have changed medication or supplementation that might affect study outcomes in the last 3 months.
• Take vitamin, mineral, herbal supplementation, or medications that may have an impact on study outcomes.
• Are already involved in another research project within 30 days of commencement of the present study that in the opinion of the investigators will be unsuitable for this study.
• Are pregnant or breastfeeding.
• Show unwillingness to be randomized to either experimental group.
• Failure to satisfy the investigator regarding suitability to participate for any other reason.
• Are unwilling or unable to provide written informed consent.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

American Egg Board

OTHER

Sponsor Role: collaborator

University of South Australia

OTHER

Sponsor Role: lead

Responsible Party

Prof. Jonathan Buckley

Dean of Programs (Human Performance)

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Jonathan D Buckley, PhD

Role: PRINCIPAL_INVESTIGATOR

University of South Australia

Locations

University of South Australia Clinical Trial Facility

Adelaide, South Australia, Australia

Countries

Australia

References

Carter S, Hill AM, Yandell C, Wood L, Coates AM, Buckley JD. Impact of dietary cholesterol from eggs and saturated fat on LDL cholesterol levels: a randomized cross-over study. Am J Clin Nutr. 2025 Jul;122(1):83-91. doi: 10.1016/j.ajcnut.2025.05.001. Epub 2025 May 6.

Reference Type: DERIVED

PMID: 40339906 (View on PubMed)

Carter S, Hill AM, Yandell C, Buckley JD, Coates AM. Study protocol for a 15-week randomised controlled trial assessing the independent effects of high-cholesterol and high-saturated fat diets on LDL cholesterol. BMJ Open. 2024 Jan 25;14(1):e081664. doi: 10.1136/bmjopen-2023-081664.

Reference Type: DERIVED

PMID: 38272555 (View on PubMed)

Other Identifiers

204327

Identifier Type: -

Identifier Source: org_study_id