Revisiting Dietary Cholesterol Recommendations: Does the Evidence Support a Limit of 300 mg/d?
- 836 Downloads
The perceived association between dietary cholesterol (DC) and risk for coronary heart disease (CHD) has resulted in recommendations of no more than 300 mg/d for healthy persons in the United States. These dietary recommendations proposed in the 1960s had little scientific evidence other than the known association between saturated fat and cholesterol and animal studies where cholesterol was fed in amounts far exceeding normal intakes. In contrast, European countries, Asian countries, and Canada do not have an upper limit for DC. Further, current epidemiologic data have clearly demonstrated that increasing concentrations of DC are not correlated with increased risk for CHD. Clinical studies have shown that even if DC may increase plasma low-density lipoprotein (LDL) cholesterol in certain individuals (hyper-responders), this is always accompanied by increases in high-density lipoprotein (HDL) cholesterol, so the LDL/HDL cholesterol ratio is maintained. More importantly, DC reduces circulating levels of small, dense LDL particles, a well-defined risk factor for CHD. This article presents recent evidence from human studies documenting the lack of effect of DC on CHD risk, suggesting that guidelines for DC should be revisited.
KeywordsDietary cholesterol LDL cholesterol HDL cholesterol LDL size Clinical studies Epidemiologic data Eggs
Dr. Fernandez and her institution have received a grant from the American Egg Board. No other potential conflicts of interest relevant to this article were reported.
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
- 3.•• Genest J, McPherson R, Frolhlich J, et al.: 2009 Canadian Cardiovascular Society/Canadian guidelines for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in the adult–2009 recommendations. Can J Cardiol 2009, 25:567–579. This is an updated guideline for diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in adults. The article discusses well-established risk factors for CHD, including elevated concentrations of LDL-C and emerging factors such as inflammatory markers and lipoprotein(a). Nutrition recommendations focus on maintenance of healthy weight and reduction of sugars, saturated fat and trans fat, and salt. There is no recommendation for dietary cholesterol.Google Scholar
- 4.• Pai HY, Kim CI, Moon HK, et al.: 2008 Dietary goals and dietary guidelines for Korean adults. Korean J Nutr 2008, 41:887–899. This article describes the Nutritional health plan for Korea in 2010. Recommendations that are emphasized are balance of energy intake and physical activity, food safety, and limitations of salt intake and total fat. There are no recommendations for dietary cholesterol.Google Scholar
- 5.Ministry of Health: Food and Nutrition Guidelines for Healthy Adults. New Zealand: Ministry of Health; 2003:18–21.Google Scholar
- 6.National Institute of Nutrition. Available at http://www.invinindia.org. Accessed June 5, 2010.
- 7.Task Force Members, Graham I, Atar D, Borsch-Johnsen K, et al.: European guidelines on cardiovascular disease prevention in clinical practice: executive summary. Fourth Joint Task Force of the European Society of Cardiology and Other societies on cardiovascular disease prevention in clinical practice. Eur Heart J 2007, 28:2375–2414CrossRefPubMedGoogle Scholar
- 8.McNamara DJ: Cholesterol intake and plasma cholesterol, an update. J Am Coll Nutr 1997, 16:530–534.Google Scholar
- 10.Song WO, Kerver JM: Nutritional contribution of eggs to American diets. J Am Coll Nutr 2000, 5(Suppl):556S–562S.Google Scholar
- 13.Weggermans RM, Zock PL, Katan MB: Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: a meta-analysis. Am J Clin Nutr 2001, 73:885–891.Google Scholar
- 14.Okuyama H, Ichikawa Y, Sun Y, et al.: The cholesterol hypothesis, its basis and its faults. World Rev Nutr Dietetics 2007, 96:1–17.Google Scholar
- 15.• Conti AA, Dilaghi B, Modesti PA, Nozzoli C: New evidence in cardiovascular medicine, general practice and public health. Intern Emerg Med 2009, 4:343–345. In this article, the authors assess all dietary interventions using DC or eggs and derive their own conclusions. They point out that short-term effects where there is a rise in plasma cholesterol with DC should be interpreted with caution because they differ from long-term effects where there is no relationship between DC and plasma cholesterol.CrossRefPubMedGoogle Scholar
- 16.•• Lloyd-Jones DM, Hung Y, Labarthe D, Mozzafariun D: AHA Special Report. Defining and setting National goals for cardiovascular health promotion and disease reduction. Circulation 2010, 121:586–613. This is a comprehensive report on national goals for cardiovascular health promotion in the United States in which emphasis is made on lifestyle factors and health for adolescents and children. Among the dietary guidelines, trans fat and saturated fat are recommended to be restricted, but there is no specific mention of dietary cholesterol.CrossRefPubMedGoogle Scholar
- 17.•• Gidding SS, Lichtenstein AH, Faith MS, et al.: Implementing AHA Pediatric and Adult Nutrition Guidelines: a scientific statement from the AHA Nutrition Committee of the Council on Nutrition, Physical Activity and Metabolism. Circulation, 2009:119:1161–1175. These are important dietary guidelines crafted by the AHA Nutrition Committee. Emphasis is placed on reducing salt intake to decrease hypertension and the DASH diet is recommended. There are recommendations against consuming saturated fat and trans fat and there are no specific guidelines regarding dietary cholesterol.CrossRefPubMedGoogle Scholar
- 18.•• Barraj L, Tran N, Mink P, et al.: Comparison of egg consumption with other modifiable coronary heart disease lifestyle risk factors: a relative risk apportionment study. Risk Anal 2009, 29:401–415. This study supports the lack of relationship between eggs and CHD. The authors created a model to evaluate risk factors for CHD using data from the Nurse’s Health Study and the Health Professionals Follow-up Study plus National Health and Nutrition Examination Survey data. They concluded that 1 egg per day contributes to less than 1% of the CHD mortality CrossRefPubMedGoogle Scholar
- 22.Djousee L, Gaziano JM: Egg consumption in relation to cardiovascular disease and mortality. The Physicians Health Study. Am J Clin Nutr 2008, 87:964–969.Google Scholar
- 23.• Houston DK, Ding J, Lee JS, et al.: Dietary fat and cholesterol and risk of cardiovascular disease in older adults: The Health ABC Study. Nutr Met Card Dis 2010 (in press). The associations between dietary fat, DC, and eggs were analyzed in 1941 adults aged 70 to 79 years. Dietary cholesterol and egg consumption were associated with increased CHD risk only in individuals with type 2 diabetes.Google Scholar
- 30.• Fernandez ML, Webb D: The LDL to HDL cholesterol ratio as a valuable tool to evaluate coronary heart disease risk. The impact of dietary cholesterol. J Am Coll Nutr 2008, 27:1–5. This review provides evidence on the importance of the LDL-C/HDL-C ratio in assessing the risk for CHD, with data derived from several large clinical studies. In addition, the effect of dietary cholesterol in maintaining the ratio across different populations is discussed.PubMedGoogle Scholar
- 32.•• Mutungi G, Ratliff J, Puglisi M, et al.: Dietary cholesterol from eggs increases HDL cholesterol in overweight men consuming a carbohydrate restricted diet. J Nutr 2008, 138:272–276. This study is a weight loss intervention in which participants followed a carbohydrate-restricted diet. Half of the participants were consuming 3 whole eggs whereas the other half were consuming 3 egg substitutes for a period of 12 weeks. At the end of the intervention, although all participants had significant decreases in plasma triglycerides and no changes in LDL-C, only those individuals in the egg group had a significant increase in plasma HDL-C.PubMedGoogle Scholar
- 33.• Harman NL, Leeds AR, Griffin BA: Increased dietary cholesterol does not increase plasma low density lipoprotein when accompanied by an energy-restricted diet and weight loss. Eur J Nutr 2008, 47:287–293. In this study, a combination of increasing dietary cholesterol and weight loss was tested in people consuming 2 eggs per day (n = 24) or no eggs (n = 21). Energy intake was reduced and participants lost weight. There were no changes in LDL-C for any of the participants in the study. The authors concluded that cholesterol-rich foods should not be excluded from dietary advice in those patients losing weight CrossRefPubMedGoogle Scholar
- 34.Ata S, Barona J, Kopec R, et al.: Consumption of one regular egg or a lutein-enriched egg per day increases HDL cholesterol, reduces apolipoprotein B and the number of small LDL particles while increasing plasma carotenoids and macular pigment density in adult subjects. FASEB J 2010, 24:A92.4.Google Scholar
- 35.• Mayurasakorn K, Srisura W, Sitphahul P, Hongto PO: High-density lipoprotein cholesterol changes after continuous egg consumption in healthy adults. Med Assoc Thai 2008, 91:400–407. In this study, 56 individuals 35 years of age consumed 1 additional egg per day. There were no changes in LDL-C after 12 weeks and HDL-C increased.Google Scholar
- 37.Third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). Final report. Circulation 2002, 106:3143–3421.Google Scholar
- 42.•• Mutungi G, Waters D, Ratliff J, et al.: Eggs distinctly modulate plasma carotenoid and lipoprotein subclasses in adult men following a carbohydrate restricted diet. J Nutr Biochem 2010, 21:261–267. In this study, participants (n = 30) followed a carbohydrate-restricted diet. Half of the participants were randomly assigned to consume 3 eggs per day and the other half 3 egg substitutes per day. Individuals consuming the whole eggs had significant increases in HDL-C, large HDL, and large LDL compared with those fed the egg substitutes. In addition, they also experienced a greater decrease in small LDL, indicating that egg consumption beneficially altered all atherogenic lipoproteins. Further, there were significant decreases in apolipoprotein B, indicating a decreased number of overall atherogenic particles.CrossRefPubMedGoogle Scholar
- 44.Subczynski WK, Wisniewska A, Widomska J: Location of macular xanthophylls in the most vulnerable regions of photoreceptor outer-segment membranes. Arch Biochem Biophys 2010 (in press).Google Scholar
- 45.•• Vishwanathan R, Goodrow-Kotyla EF, Wooten BR, et al.: Consumption of 2 and 4 egg yolks/d for 5 wk increases macular pigment concentrations in older adults with low macular pigment taking cholesterol-lowering statins Am J Clin Nutr 2009, 90:1272–1279. This study was conducted in older adults. The key findings are that participants did not experience an increase in LDL-C after consuming 2 to 4 egg yolks during a 5-week period and that there were increases in macular pigment density due to the high content of lutein in the eggs.CrossRefPubMedGoogle Scholar
- 52.• Ratliff JC, Leite JO, DeOgburn R, et al.: Consuming eggs for breakfast influences plasma glucose and ghrelin, while reducing caloric intake during the next 24 hours in adult men. Nutrition Res 2010, 30:96–103. In this study, a comparison was made in the same participants of an egg-based versus a bagel-based breakfast on kilocalorie intake in the next 24 hours on appetite and on plasma ghrelin concentrations. Participants consumed a lighter lunch after the egg breakfast. They also consumed 400 kcal less in the next 24 hours and had lower levels of plasma ghrelin.CrossRefGoogle Scholar
- 54.• Eckel RH: Egg consumption in relation to cardiovascular disease and mortality: the story gets more complex. Am J Clin Nutr 2008, 87:799–800. This editorial reviews the effects of eggs on cardiovascular disease from data coming from the Physicians’ Health study. It concluded that diabetic individuals could benefit from restricting egg intake. However, the author pointed out that eggs can be part of a healthy diet.PubMedGoogle Scholar