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What is the effect of dietary cholesterol intake on risk of cardiovasculardisease?Conclusion

Moderate evidence from epidemiologic studies relates dietary cholesterol intake to clinicalcardiovascular disease (CVD) end-points. Many randomized clinical trials on dietarycholesterol use eggs as the dietary source. Independent of other dietary factors, evidencesuggests that consumption of one egg per day is not associated with risk of coronary heartdisease or stroke in healthy adults, although consumption of more than seven eggs perweek has been associated with increased risk. An important distinction is that amongindividuals with type 2 diabetes, increased dietary cholesterol intake is associated withCVD risk.

Grade

Moderate

Evidence Summary Overview

The Nutrition Evidence Library (NEL) systematic review identified 16 studies publishedsince 1999 that evaluated the effect of dietary cholesterol intake on cardiovasculardisease (CVD) risk conducted in the US, Europe, Mexico and Japan. These studiesfocused on dietary cholesterol, in the absence of dietary saturated fat. Eight randomizedcontrolled trials (RCTs), including two methodologically strong studies (Ballesteros, 2004;Knopp, 2003) and six methodologically neutral studies (Goodrow, 2006; Greene, 2005;Harman, 2008; Mutungi, 2008; Reaven, 2001; Tannock, 2005) with sample size rangingfrom 28 to 201 subjects were reviewed. Five prospective cohort studies, including fourmethodologically strong studies (Djousse, 2008; Hu, 1999; Qureshi, 2007; Tanasescu,2004) and one methodologically neutral study (Nakamura, 2006) ranging in size from5,687 to 80,082 subjects, were reviewed. One meta-analysis of 17 studies wasmethodologically strong (Weggemans, 2001), and two systematic reviews, onemethodologically strong pooled analysis of 167 cholesterol feeding studies in 3,519subjects (McNamara, 2000) and one methodologically neutral review of eight prospectivecohort studies on dietary cholesterol and six prospective cohort studies on eggs(Kritchevsky and Kritchevsky, 2000) met the eligibility criteria and were reviewed. Themajority of these articles reported on comparisons of egg vs. egg substitute or no eggintake. In studies comparing eggs vs. egg substitute, one randomized controlled trial(Ballesteros, 2004) and one pooled analysis (McNamara, 2000 ) showed that low-densitylipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol increased in hyper-responders, but did not change in hypo-responders; overall, the LDL:HDL did not changein hypo- or hyper-responders. Identification of hypo-and hyper-responders showed inter-individual variation to dietary cholesterol that may result in differing health outcomes forindividuals with different genetic predispositions.

- NEL http://www.nel.gov/evidence.cfm?evidence_summary_id=250206

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Harman et al, (2008) found that LDL-C decreased in both egg and egg substitute groupsand two studies in elderly adults (Greene, 2005; Goodrow, 2006) indicated that LDL-C andHDL-C were not affected by egg intake. Two RCTs showed an increase in LDL-C diameterin the egg group (Ballesteros, 2004; Greene, 2005). Two RCTs in 65 insulin-sensitive and75 insulin-resistant subjects determined that egg consumption was associated withincreased LDL-C, but only in insulin-sensitive subjects (Knopp, 2003; Tannock, 2005).However, Reaven et al, (2001) found that high cholesterol intake did not increase LDL-C ineither insulin-sensitive or insulin-resistant sub-groups. All studies that measured HDL-Cfound that HDL-C was increased with egg consumption, and one such study was in acarbohydrate (CHO)-restricted diet background (Mutungi, 2008). One study assessedmarkers of inflammation and found increased C-reactive protein (CRP) and serum amyloidA with high egg consumption, but found no difference in circulating cytokines (Tannock,2005). One meta-analysis of 17 studies indicated that high dietary cholesterol intakeincreased the total cholesterol (TC):HDL-C ratio. However, this effect was attenuated inthe low saturated fatty acid (SFA) subgroup (Weggemans, 2001).

In the prospective cohort studies, Djousse et al, (2001) found that egg consumption up tosix eggs per week in the Physicians Health Study was not associated with risk of all-causemortality, but consumption of more than seven eggs per week was associated with a 23%increased risk of death. In the Japan Public Health Center study, egg consumption was notassociated with coronary heart disease (CHD) incidence (Nakamura, 2006). In Nutritionand Health Examination Examination Survey I (NHANES I), no relationship wasestablished between egg consumption (more than six eggs per week) and risk of stroke orischemic stroke, and risk of myocardial infarction (MI) and all-cause mortality was notdifferent between egg and non-egg consumption groups (Qureshi, 2007). A combinedanalysis of the Health Professionals Follow-up Study (HPFS) and the Nurses HealthStudy (NHS), found no significant (NS) association between egg consumption and risk ofCHD or stroke in men or women (Hu, 1999). A review of epidemiological studies(Kritchevsky and Kritchevsky, 2000) showed there was no association betweenconsumption of one egg per day and risk of cardiovascular disease (CVD), but only innon-diabetic men and women. Furthermore, three methodologically strong prospectivecohort studies warned that egg consumption was associated with increased CVD risk insubjects with type 2 diabetes (T2D) (Djousse, 2001; Hu, 1999; Tanasescu, 2004) and thiswarrants further investigation.

Evidence Summary Paragraphs

Ballesteros et al, 2004 (positive quality) This was a randomized crossover trial conductedin Mexico to evaluate the effects of dietary cholesterol provided by whole eggs on plasmalipids and LDL-C atherogenicity in a pediatric population. Children were divided into twogroups and randomly assigned to either the egg or egg substitute intervention for 30 daysfollowed by a three-week washout period, followed by the opposite intervention for 30days. The children consumed either two whole eggs (providing 518mg additional dietarycholesterol) or the equivalent amount of egg whites with added color, served scrambled forbreakfast in the school cafeteria. On weekends, eggs and egg substitute were packed forconsumption and parents were instructed on proper administration. Sixty children [30 boys


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(aged 10.61.6 years) and 30 girls (aged 10.21.5 years)] were enrolled in the study; 54children (25 boys and 29 girls) completed the trial. Children were classified ashyporesponders (N=36), defined as no increase or 0.06mmol/L in plasma cholesterol for 100mg cholesterol. During the egg consumptionperiod, the hyperresponders had an elevation of both LDL-C (from 1.540.38 to1.930.36mmol/L) and HDL-C (from 1.230.26 to 1.350.29mmol/L), whilehyporesponders had NS alterations in plasma LDL-C or HDL-C. All subjects, however, hadan increase in LDL peak diameter (P

or the same volume of egg substitute for 30 days, followed by a three-week washoutperiod, and then assigned to the opposite intervention for 30 days. A seven-day dietaryrecord was collected during each period. Forty-two older adults (13 men over 60 years ofage, 29 postmenopausal women, no age specified) enrolled and completed the trial. Inboth men and women, TC (P

Insulin sensitive (IS, N=65); insulin resistant (IR, N=75; and obese insulin-resistant (OIR,N=58). The intervention was consumption of zero, two or four eggs per day with abackground National Cholesterol Education Program (NCEP) Step 1 diet (monitoredby three-day food records). Consumption of four eggs per day was associated with anincrease in LDL-C in the IS (increased 7.8%) and IR (increased 3.3%) groups (bothP

related to the risk of CHD; the multivariate hazard ratio (HR) of CHD in subjects with TC>2,400 vs.

into three a priori defined groups: Lean insulin-sensitive (LIS), N=66; lean insulin-resistant(LIR), N=78; and obese insulin resistant (OIR), N=59. For this analysis, subjectsingested zero or four eggs per day for four weeks in random order, with a backgroundNCEP Step 1 diet (monitored by three-day food records) and four-week washout. Eggfeeding was associated with significant increases in both CRP and serum amyloid A (SAA)in the LIS group (both P

whole eggs (providing 518mgadditional dietary cholesterol)or the equivalent amount ofegg whites with added color,served scrambled for breakfastin the school cafeteria.

On weekends, eggs and eggsubstitute were packed forconsumption and parents wereinstructed on properadministration.

Djousse et al2008

Study Design:ProspectiveCohort Study

Class: B

Rating:

Physicians'Health Study.

Averagefollow-up of 20years.

21,327 American malephysicians.

Mean age: 53.79.5 years,range 40-85 years.

Location: United States.

Examined association betweenegg consumption and riskof CVD and mortality.

Information on eggconsumption obtainedat baseline, 24, 48, 72, 96 and120 months using asemi-quantitative FFQ.


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Goodrow et al2006

Study Design:RandomizedCrossoverTrial

Class: A

Rating:

Duration: 18weeks.

N=33 older adults [seven men(mean age 774 years) and 26women (mean age 812years)] enrolled andcompleted the trial.


The 18-week trial consisted offour phases:

Phase I (baseline period;participants instructed tolimit consumption of foods inlutein and zeaxanthinand avoid eggs or -eggcontent foods)

Phase II (five-weekintervention; subjectsconsumed either no egg oregg substitute or one egg perday in addition to their normaldiet)

Phase III (four-week washoutperiod similar to phase I)

Phase IV (five-week crossoverintervention from phase II).

A seven-day dietrecord obtained from eachsubject during each phase ofthe study.

Greene CM etal 2005

Study Design:RandomizedCrossoverTrial

Class: A

Rating:

Two 30-dayinterventionperiodsseparated by athree-weekwashout period.

N=42 older adults (13 men>60 years of age, 29postmenopausal women)enrolled and completedthe trial.

Age not specified.

Location: United States

Subjects assigned to eitherequivalent of three eggs perday (containing~640mg dietary cholesterol)or same volume of eggsubstitute for 30 days, followedby a three week washoutperiod, and then assignedto opposite intervention for 30days.

Seven-day dietaryrecord collected during eachperiod.


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Harman et al2008

Study Design:RandomizedControlledTrial

Class: A

Rating:

Duration: 12weeks.

N=53 subjects randomlyassigned.

N=45 subjects completed trial:

N=24in group consuming eggs(eight male, 17 female,mean age 44.98.4years)N=21 in control group(six male, 15 female,mean age 43.010.5years).

Location: United Kingdom.

Subjects were randomlyassigned to one of two paralleldietary interventions:

1) An energy restricted diet (by 500-1,000kcal per day)which included two eggs(N=27)

2) No eggs (N=26) per dayfor 12 weeks.

All subjects received dieteticcounseling and individualizeddiet plan andweight loss monitored throughregular meetings with adietitian.

Seven-day fooddiary completed at baselineand after six weeks.

Hu FB,Stampfer MJet al, 1999


Class: B

Rating:

Analysis of:

1) HealthProfessionalsFollow-up Study(HPFS);eight-yearfollow-up

2) Nurses HealthStudy (NHS);14-year follow-up.

N=37,851 men (aged 40-75years).

N=80,082 women (aged 34-59years).

Followed for incident non-fatalMI, fatal CHD and stroke.

Egg intake determined withFFQ.


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Knopp RH,Retzlaff B etal, 2003


Double-blinded,randomized,three-periodcrossover clinicaltrial with threefour-weekinterventionperiods

Subjects divided based onBMI and insulin sensitivityto three groups:

N=65 Insulin sensitive (IS)

N=75 Insulin resistant (IR)

Consumption of zero, twoor four eggs per day.

Background NCEP Step 1 diet(monitored by three-day foodrecords).


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Class: A

Rating:

with four-weekwashout.

N=58 Obese, insulin-resistant(OIR).

KritchevskySB andKritchevsky D,2000

Study Design:Meta-analysisor SystematicReview

Class: M

Rating:

Summary ofepidemiologicalevidence relatingdietarycholesterol andegg intake toCVD.

N=8 prospective cohortstudies relating dietarycholesterol and risk of CVD.

N=6 prospective cohortstudies relating eggconsumption and risk of CVD.

Dietary cholesterol.

Egg cholesterol.

McNamaraDJ, 2000


Pooledquantitativeanalysis.

N=167 articles on cholesterolfeeding studies in 3,519subjects.

1960-2000.

Studies limited to cross-overdesign with cholesterol intake

Studies used dietarycholesterol concentrationsfrom (100-300mg per day) to (3-5g per day) intakesadjusted for body weight to70kg and plasma cholesterolto 100mg per day .


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Class: M

Rating:

sole variable.

Mutungi et al2008


Class: A

Rating:

Duration: 12weeks.

N=31 males enrolled.

N=28 completed the trial.

Age: 40-70 years.


Compared effects of aCHO-restricted diet incholesterol (provided by eggs)to one in cholesterol(provided by eggsubstitutes) on the variables ofmetabolic syndrome.

CHO-restricted diet composedof 10-15% of energy as CHO,25-30% as PRO and 55-60%as fat; energy intake notrestricted.

Subjects received weeklyfollow-up counseling andeducation and body mass andcompliance measured at visits.

Three-day food recordsobtained at baseline andfive-day food recordscompleted during weeksone, six and 12.


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Nakamura etal 2006


Class: B

Rating:

Duration:Subjects followedthroughDecember 2001.

Two cohorts were analyzed:

Cohort I, composed of 54,350residents in four specificprefectures of Japan, aged40-59 in 1990

Cohort II, composed of 62,288residents in five specificprefectures of Japan, aged40-69 in 1993-1994.

Location: Japan.

Examined association betweenegg consumption and TCconcentration and CHDincidence.

Egg consumption assessedthrough FFQ.

Qureshi et al2007


Class: B

Rating:

Duration: 20-yearfollow-up.

N=9,734 adults (3,756 males,5,978 females) includedin analysis, from theNHANES-I EpidemiologicFollow-up Study (NHEFS).

Age: 25-74 years at timeof original study.


Studied the associationbetween egg intake and riskof CVD and mortality.

Egg consumption wascategorized into no or six eggsper week, during four follow-upperiods in 1982-1984, 1986,1987 and 1992.


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Reaven GM,Abbasi F et al,2001


Class: A

Rating:

N=65 healthy,postmenopausal women (31insulin resistant, 34 insulinsensitive).

12-week trial:

Four weeks oflow-cholesterol baselineFour-week washoutFour weeks on 319mg,523mg, or 941mgcholesterol per day.

Cholesterol was from eggs.

Tanasescu etal 2004


Class: B

Rating:

Nurses' HealthStudy.

Duration: 18-yearfollow-up.

N=5,672 female nurses whoreported a physician'sdiagnosis of diabetes at age>30 years on any follow-upquestionnaire.

Age: 30-55 years in 1976.


Assessed relationship betweendifferent types of dietary fatand cholesteroland risk of CVD amongwomen with T2D.

Nurses' Health Study started in1986 with follow-upquestionnaires sent every twoyears until 1996.

Dietary fat and cholesterolassessed throughsemi-quantitative FFQ.


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Tannock LR,O'Brien KD etal, 2005


Class: A

Rating:

N=201 subjects dividedinto three defined groups:

1) N=66 Lean insulin-sensitive(LIS)

2) N=78 Lean insulin-resistant(LIR)

3) N=59 Obese insulinresistant (OIR).

Zero or four eggs per dayfor four weeks.

Background NCEP Step 1 diet(monitored by three-day foodrecords).

Four-week washout.


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WeggemansRM, Zock PLet al, 2001


Class: M

Rating:

Studies identifiedin MEDLINE andBiologicalAbstracts(1974-1999).

Men and women with a wideage range from NorthAmerica, Europe and SouthAfrica.

Location: International.

N=17 with 556 subjects metinclusion criteria (of 222studies identified).

Research Design and ImplementationFor a summary of the Research Design and Implementation results, click here.

Worksheets Ballesteros MN, Cabrera RM, Saucedo Mdel S, Fernandez ML. Dietary cholesterol

does not increase biomarkers for chronic disease in a pediatric population fromnorthern Mexico. Am J Clin Nutr. 2004 Oct;80(4):855-61.

Djouss L, Gaziano JM. Egg consumption in relation to cardiovascular disease andmortality: the Physicians' Health Study. Am J Clin Nutr. 2008 Apr;87(4):964-9.

Goodrow EF, Wilson TA, Houde SC, Vishwanathan R, Scollin PA, Handelman G,Nicolosi RJ. Consumption of one egg per day increases serum lutein and zeaxanthinconcentrations in older adults without altering serum lipid and lipoprotein cholesterolconcentrations. J Nutr. 2006 Oct;136(10):2519-24.

Greene CM, Zern TL, Wood RJ, Shrestha S, Aggarwal D, Sharman MJ, Volek JS,Fernandez ML. Maintenance of the LDL cholesterol:HDL cholesterol ratio in an elderlypopulation given a dietary cholesterol challenge. J Nutr. 2005 Dec;135(12):2793-8.


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Harman NL, Leeds AR, Griffin BA. Increased dietary cholesterol does not increaseplasma low density lipoprotein when accompanied by an energy-restricted diet andweight loss. Eur J Nutr. 2008 Sep;47(6):287-93. Epub 2008 Aug 26. Erratum in: Eur JNutr. 2008 Oct;47(7):408.

Hu FB, Stampfer MJ, Rimm EB, Manson JE, Ascherio A, Colditz GA, Rosner BA,Spiegelman D, Speizer FE, Sacks FM, Hennekens CH, Willett WC. A prospective studyof egg consumption and risk of cardiovascular disease in men and women. JAMA. 1999Apr 21; 281 (15): 1,387-1,394.

Knopp RH, Retzlaff B, Fish B, Walden C, Wallick S, Anderson M, Aikawa K, KahnSE. Effects of insulin resistance and obesity on lipoproteins and sensitivity to eggfeedings. Arterioscler Thromb Vasc Biol. 2003 Aug 1; 23(8): 1,437-1,443.

Kritchevsky SB, Kritchevsky D. Egg consumption and coronary heart disease: Anepidemiologic overview. J Am Coll Nutr. 2000 Oct; 19 (5 Suppl): 549S-555S.

McNamara DJ. The impact of egg limitations on coronary heart disease risk: Do thenumbers add up? J Am Coll Nutr. 2000 Oct; 19 (5 Suppl): 540S-548S.

Mutungi G, Ratliff J, Puglisi M, Torres-Gonzalez M, Vaishnav U, Leite JO, Quann E,Volek JS, Fernandez ML. Dietary cholesterol from eggs increases plasma HDLcholesterol in overweight men consuming a carbohydrate-restricted diet. J Nutr. 2008Feb;138(2):272-6.

Nakamura Y, Iso H, Kita Y, Ueshima H, Okada K, Konishi M, Inoue M, Tsugane S.Egg consumption, serum total cholesterol concentrations and coronary heart diseaseincidence: Japan Public Health Center-based prospective study. Br J Nutr. 2006Nov;96(5):921-8.

Qureshi AI, Suri FK, Ahmed S, Nasar A, Divani AA, Kirmani JF. Regular eggconsumption does not increase the risk of stroke and cardiovascular diseases. Med SciMonit. 2007 Jan;13(1):CR1-8. Epub 2006 Dec 18.

Reaven GM, Abbasi F, Bernhart S, Coulston A, Darnell B, Dashti N, Kim H, KulkarniK, Lamendola C, McLaughlin T, Osterlund L, Schaff P, Segrest J. Insulin resistance,dietary cholesterol and cholesterol concentration in postmenopausal women.Metabolism. 2001 May; 50 (5): 594-597.

Tanasescu M, Cho E, Manson JE, Hu FB. Dietary fat and cholesterol and the risk ofcardiovascular disease among women with type 2 diabetes. Am J Clin Nutr. 2004Jun;79(6):999-1005.

Tannock LR, O'Brien KD, Knopp RH, Retzlaff B, Fish B, Wener MH, Kahn SE, ChaitA. Cholesterol feeding increases C-reactive protein and serum amyloid A levels in lean


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insulin-sensitive subjects. Circulation. 2005 Jun 14; 111(23): 3,058-3,062.

Weggemans RM, Zock PL, Katan MB. Dietary cholesterol from eggs increases theratio of total cholesterol to high-density lipoprotein cholesterol in humans: Ameta-analysis. Am J Clin Nutr. 2001 May; 73(5): 885-891.

Related Resources

2010 Dietary Guidelines ReportUSDA Center for Nutrition Policy and Promotion (CNPP)ChooseMyPlateSuperTracker

Physical Activity GuidelinesFood and Nutrition Services (FNS)Food and Nutrition Information Center (FNIC)USDA

Know Your Farmer, Know Your FoodThe Peoples GardenNutrition.gov


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