This is a research paper that I wrote for my English class this semester. I wanted to share it on this blog because it’s about eggs, cholesterol, and the Dietary Guidelines, three things that definitely impact the ancestral health community!
With rising rates of obesity and diabetes, most Americans feel more pressure than ever to make the right food choices. However, the country’s primary source of nutritional guidance – the Dietary Guidelines for Americans – has been criticized for being misleading, inaccurate, and potentially harmful to public health. In this paper, I present eggs as a ‘case study’ to strengthen the criticisms that others have brought against the Dietary Guidelines. The Guidelines advocate limiting egg consumption because of their high cholesterol content. However, having reviewed the scientific literature on cholesterol and health, I conclude that there is no documented health benefit to limiting dietary cholesterol. Additionally, eggs are an excellent source of choline, a nutrient that is sorely lacking in the diets of most Americans. For these reasons, the Dietary Guidelines should actually encourage egg consumption, rather than limit it.
Obesity and diabetes are becoming increasingly prevalent in America, and there is a lot of pressure on Americans to make the right food choices. However, the Internet and other forms of media often provide confusing or contradictory information about what to eat. To allay this confusion, the federal government provides nutritional guidance by issuing the Dietary Guidelines for Americans. Unfortunately, the Guidelines may not be the accurate, science-based document they claim to be. The Guidelines are woefully inaccurate regarding eggs, and this inaccuracy is where I have focused my research. I assert that, instead of limiting egg consumption as they do now, the Dietary Guidelines should encourage it. I say this for two reasons:
- Despite what the Guidelines say, evidence does not show a relationship between higher intake of cholesterol and higher risk of cardiovascular disease.
- Eggs are an important source of nutrients, such as choline, that are otherwise lacking in the American diet.
In this paper, I will examine each of these points in turn to prove that the Dietary Guidelines should encourage egg consumption.
The Dietary Guidelines were jointly published by the US Departments of Agriculture (USDA) and Health and Human Services (HHS) in 1980, and are revised and updated every five years (USDA viii). Regarding eggs, the 2010 Dietary Guidelines say:
Moderate evidence shows a relationship between higher intake of cholesterol and higher risk of cardiovascular disease. Independent of other dietary factors, evidence suggests that one egg (i.e., egg yolk) per day does not result in increased blood cholesterol levels, nor does it increase the risk of cardiovascular disease in healthy people. Consuming less than 300 mg per day of cholesterol can help maintain normal blood cholesterol levels. Consuming less than 200 mg per day can further help individuals at high risk of cardiovascular disease (USDA 27).
In other words, the Guidelines recommend capping cholesterol intake at 300mg. Because one large egg has about 185mg cholesterol, this cap automatically limits egg consumption to one per day at most. This advice is not new; in fact, the recommendation to limit cholesterol to 300mg per day first appeared in the Dietary Goals for Americans issued in 1977 (Slavin 245). What is alarming is that, despite the accumulation of evidence to the contrary, this guideline has persisted for over 30 years.
Many prominent scientists and researchers have already recognized the need to reform the Dietary Guidelines. Even Dr. Joanne Slavin, a professor of Nutrition at the University of Minnesota who helped create the 2010 Dietary Guidelines, recognizes its significant shortfalls. Other prominent critics include Dr. Paul Marantz, Professor of Clinical Epidemiology and Population Health at the Albert Einstein College of Medicine; and Dr. Dariush Mozaffarian, Assistant Professor of Medicine at Harvard Medical School. Collectively, these researchers and others have identified areas throughout the entire document that should be reexamined (Slavin 247). In fact, a few researchers have even written specifically about eggs and the Dietary Guidelines. One such researcher is Dr. Maria Fernandez, a Nutrition professor at the University of Connecticut, and she concludes repeatedly that the Guidelines are unnecessarily limiting egg consumption, and the 300mg cholesterol cap should be removed (Fernandez). I take her argument further by asserting that the Dietary Guidelines should encourage greater egg consumption, rather than simply removing the limit. I will also analyze the scientific support specifically used by the Dietary Guidelines, and I will incorporate my own research including a survey and an interview.
As the above quote from the 2010 Dietary Guidelines indicates, the only reason the Dietary Guidelines limit egg consumption is because of their high cholesterol content. However, it’s clear from looking at the evidence that dietary cholesterol does not increase the risk of heart disease. First, I will review the evidence from scholarly journal articles. Then, I will analyze the evidence used by the Dietary Guidelines themselves.
As I previously mentioned, Dr. Maria Fernandez discusses the science of eggs and cholesterol in her papers “Rethinking dietary cholesterol” (2012), “Effects of eggs on plasma lipoproteins in healthy populations” (2010), and “Revisiting Dietary Cholesterol Recommendations: Does the Evidence Support a Limit of 300 mg/d?” (2010). Sharon Natoli et al. also reviewed the evidence a few years earlier in their paper “Unscrambling the research: Eggs, serum cholesterol and coronary heart disease” (2007), and came to similar conclusions. By reviewing epidemiological studies, clinical trials, and physiological mechanisms, these papers invalidate the assumption that dietary cholesterol negatively impacts health (Fernandez, “Rethinking,” 118). In fact, as Lecerf and Lorgeril from the British Journal of Nutrition point out, dietary cholesterol actually has little impact on blood cholesterol levels at all, and if it does, the ratio of LDL to HDL (two different carriers of cholesterol) is maintained (Lecerf 8). This is significant because many doctors consider the ratio of LDL to HDL to be more important than the absolute levels of either. Even more importantly, increased dietary cholesterol from eggs has been shown to decrease the number of small, dense LDL particles – which have been negatively implicated in heart health – and increase the number of big, ‘fluffy’ LDL particles – which appear to be harmless (Fernandez, “Rethinking,” 119). The basic takeaway from this research is that increased dietary cholesterol tends to have a positive impact on blood lipids, if it has any impact at all. This positive impact results from the transformation of LDL particles into a less atherogenic form.
With all of this evidence showing that dietary cholesterol does not have harmful health effects, it’s surprising that the Dietary Guidelines still recommend a cap of 300mg per day. In case the Dietary Guidelines used evidence that the critics did not address, I reviewed the sixteen studies selected by the Dietary Guidelines Committee itself to support this cholesterol recommendation. I found that many of these studies were the same ones referenced by Fernandez and Natoli et al. in the papers discussed above (DGAC 225). Of the fifteen studies that examined non-diabetic patients, twelve of them show no association between dietary cholesterol and increased risk of cardiovascular disease (Ballesteros, Djousse, Goodrow, Greene, Harman, Hu, Kritchevsky, McNamara, Mutungi, Nakamura, Qureshi, Reaven). Most of these studies conclude that increased cholesterol intake has “no association” with cardiovascular disease in healthy populations, but some actually conclude that increased cholesterol intake is beneficial to heart health. For example, a study by Ballasteros et al. examining a population of Mexican children concluded that “Intake of 2 eggs/d results in the maintenance of LDL:HDL and in the generation of a less atherogenic LDL” (Ballasteros). Another study surveyed a “nationally representative cohort” of American adults and concluded that “Consumption of greater than 6 eggs per week (average of 1 egg or greater per day) does not increase the risk of stroke and ischemic stroke” (Qureshi). Finally, a pooled analysis of 167 cholesterol-feeding studies concludes that although dietary cholesterol does increase plasma cholesterol, the ratio of HDL to LDL cholesterol barely changes, which “would be predicted to have little effect on heart disease risk” (McNamara). In other words, the majority of the studies that the Dietary Guidelines cite to support their cap on cholesterol actually support the opposite argument made by Fernandez and others: that increased intake of dietary cholesterol, especially from eggs, does not increase the risk of heart disease.
Choline is an essential nutrient that is lacking in the diets of the vast majority of Americans. When I interviewed Dr. Steven Zeisel, a choline researcher at UNC Chapel Hill, he estimated that only 5-10% of most age groups meet the recommended intake for choline. Dr. Zeisel pointed out that the recommended intake level is essentially a “best guess” for choline requirements, so not meeting that level does not guarantee someone is deficient; however, he speculates that a large portion of the American population would benefit from additional choline.
Choline deficiency has been clinically shown to have significant negative effects on human health, including liver and muscle damage (Zeisel 616). These symptoms are resolved when the test subjects begin consuming a high-choline diet. Choline is vitally important during pregnancy, both for proper brain development and to avoid birth defects. Fetuses and newborns have six to seven times the concentration of choline in their blood that adults have, and pregnant women also have significantly higher plasma concentrations of choline compared to non-pregnant women. One study by Shaw et al. found that “women in the lowest quartile for dietary choline intake had four times the risk of giving birth to a child with a neural tube defect compared with women in the highest quartile” (617). Granted, this is not a randomized controlled clinical trial; indeed, it would be highly unethical to conduct a trial where the health of fetuses is at stake. However, given the established importance of choline during pregnancy, the association is nonetheless compelling. Preliminary animal studies have even shown promise for the ability of choline to lessen the severity of Fetal Alcohol Syndrome.
Choline is not just important during pregnancy, however. During our interview, Dr. Zeisel explained that men and menopausal women in particular must get choline from their diets, because they cannot manufacture it. For example, when healthy men and women were given a choline deficient diet, “77% of the men and 80% of the postmenopausal women developed signs of subclinical organ dysfunction.” In this case, they developed fatty liver or muscle damage (Zeisel 615).
Given the importance of choline for human health, it is concerning that so few Americans get enough of it in their diets. It’s even more concerning that the Dietary Guidelines for Americans do not mention choline at all. According to Dr. Zeisel, choline was recognized as an essential nutrient in 1998, which should have allowed plenty of time for it to be incorporated into the 2005 or 2010 Dietary Guidelines. But instead of helping the American population get adequate choline, the Dietary Guidelines actively limit one of the best sources of choline available: eggs.
Choline Content of Selected Choline-Rich Foods
The above figure displays choline-rich foods, and you’ll notice that eggs and organ meats top the chart. Wheat germ and other meat products are also good sources, albeit to a lesser extent. Given that these are the foods highest in choline, it’s no wonder that Americans don’t meet the recommended intake. Animal organs are not the most commonly eaten food, to say the least, and the majority of wheat consumed in the US has been processed to remove the germ. Thus, I believe that eggs are the most promising way to increase Americans’ choline intake. Just one egg supplies 1/3 to ½ of the daily recommendation for choline (Caudill et al. 236). Also, according to data from the National Health and Nutrition Examination Survey (NHANES), the few people who actually met the adequate intake level for choline got a higher percentage of their choline intake from eggs (Zeisel 621). This indicates that eggs play an important role in reaching choline recommendations.
Why are the Guidelines so wrong?
In light of this information, it’s only reasonable to wonder why the current cholesterol and egg recommendations are so wrong. Part of the answer lies in the origin of these guidelines. The evidence that initially prompted the recommendations in the 1970s included data from animal studies and epidemiological studies, and current researchers generally conclude that this data was misinterpreted. (McNamara 311) In the animal studies, various species were fed cholesterol in amounts far exceeding what is normally found in foods, and they did in fact develop heart disease. However, the natural cholesterol profiles of these animals vary significantly from the cholesterol profiles of humans, so it’s impossible to extrapolate these results to humans. Additionally, the excessive amounts of cholesterol given to the animals (the equivalent of 1250-5000mg per day) would never occur in a normal human diet. The epidemiological studies were also misinterpreted, but this time because of confounding variables. Once these variables were accounted for, the positive association between dietary cholesterol and heart disease became statistically insignificant. Additionally, when rates of heart disease were plotted against egg consumption specifically, a negative trend emerged, indicating that as egg consumption increases, risk for heart disease actually decreases (316).
So we know why the cholesterol limits were created in the first place; what we don’t know is why they persist. This question is multifaceted, and answering it would involve the complex interactions between industry, politics, policy, and media. However, one of the primary reasons is simply that the recommendation to limit cholesterol has become so entrenched in ‘conventional wisdom’ that people don’t think to question it (McNamara 318). Dr. Walter Willet, chair of the Department of Nutrition at Harvard, comments that “often the recommendations are repeated so many times that people forget they were rough guesses in the first place and come to think they are hard facts” (D.Q. Haney, qtd. in McNamara). Thus, the burden of proof tends to fall on those of us trying to reverse the paradigm.
Survey Results: Eggs and Choline
I distributed a Qualtrics survey via email and Facebook to investigate factors related to egg consumption and received 67 responses. The majority of the respondents were first-year students at UNC Chapel Hill, and the data I gathered supports my belief that eggs are the most promising way to combat the widespread choline deficiency in America. It also supports my assertion that the Dietary Guidelines should not just remove the limit on egg consumption, but also encourage consumption. This data is not representative of all Americans, or even UNC Chapel Hill’s student body; however, their responses are useful as a preliminary study to establish general tendencies.
How often do you eat each of the following foods?
My survey showed that of six choline-rich foods (liver, other animal organs, eggs, soy flour, wheat germ, and bacon), only eggs are eaten on a regular basis. 86.7% of respondents never eat liver, 74.7% never eat other animal organs, and about 61% never eat wheat germ or soy flour (at least, not knowingly). 68% eat bacon 2-3 times per month or less. In sharp contrast with these other results, 68% of respondents eat eggs at least once a week, and 44% eat eggs at least 2-3 times per week.
How much do you like each of the following foods?
My survey also looked at whether or not people like each food. An impressive 83% said they like eggs, which even beat out bacon at only 69%. The majority said they “neither like nor dislike” wheat germ and soy flour (probably because they aren’t familiar with those foods), and as you can imagine, the majority disliked liver and other animal organs. Given these percentages, it’s clear that of these foods, eggs have the most potential for increasing choline consumption, because people actually like them enough to eat them on a regular basis. Additionally, the convenience factor cannot be underestimated; eggs are commonly available, and can be prepared in a variety of ways.
How healthy do you perceive each of the following foods to be?
Surprisingly, an overwhelming majority (91%) of survey respondents view eggs as either “somewhat healthy” or “very healthy.” This sample of college students does not appear to be concerned about the cholesterol content of eggs, although over half of the respondents who use egg whites or egg substitutes do this in order to reduce cholesterol intake. On the whole, though, cholesterol intake does not appear to be a concern among those surveyed.
How many eggs do you eat per week, on average?
Unfortunately, this tendency does not appear to translate into increased egg consumption. Even though the vast majority of survey respondents like eggs and perceive them to be healthy, 85% still consume eggs within the small range recommended by the Dietary Guidelines: seven or fewer per week. On top of that, 77% eat five or fewer eggs per week, 25% only eat one egg per week, and 9% eat no eggs at all. This supports my assertion that removing the limit on egg consumption in the Dietary Guidelines is not sufficient. In order for people to reap the health benefits that eggs have to offer, the Dietary Guidelines must explicitly encourage egg consumption, in addition to removing the limits.
Eggs vs. Egg Beaters
While conducting my research, I received questions about egg substitutes, so I will briefly address the differences between one substitute – Egg Beaters – and whole eggs. In short, Egg Beaters do not provide the benefits gained from eating whole eggs, because they don’t contain the egg yolk.
Essentially all of the nutrients in an egg (other than protein and a few minerals) are found in the yolk. Because Egg Beaters are made using egg whites, the nutrients in the yolk are lost. This means that choline and numerous other nutrients are thrown away when Egg Beaters are manufactured. The company does add some synthetic vitamins and minerals to the egg whites to make up for some of the lost nutrition, but you will not find choline on their ingredient list. Neither will you find lutein and zeaxanthin, two unique antioxidants found in whole eggs. Further, even if they did add back isolated versions of those components, there’s no guarantee they would provide the same benefits as they do within a whole egg. Scientists are increasingly discovering complex interactions among the components of food, and most acknowledge that whole, unprocessed foods are much more than a bag of isolated nutrients that can be recreated in a factory or lab.
But What About…?
The evidence to support a recommendation in the Dietary Guidelines to consume more eggs is compelling, but there are a couple instances where caution is warranted. The most obvious is in the case of egg allergy. Eggs are one of the top eight food allergens in the United States, and clearly, this segment of the population should not consume eggs, regardless of their health benefits.
The second case where caution is warranted is if a person is diabetic. Two of the studies I discussed earlier correlated increased egg consumption with increased risk for cardiovascular disease in diabetic patients, although not for healthy subjects (Hu, Qureshi). One other study associated egg consumption with increased mortality in diabetics (Djoussé). While no firm conclusions about the healthfulness of eggs for diabetics can be drawn yet, these findings necessitate further research. Meanwhile, extra caution is appropriate, and as always, diabetics should work with their health care practitioners to address their individual needs.
As for the rest of the American population, the evidence indicates that increased egg consumption would yield numerous benefits; however, such one-size-fits-all recommendations cause problems more often than not. In fact, one of the main criticisms of the Dietary Guidelines is that they make sweeping recommendations for a population of diverse Americans who all have individual needs. However, we must keep in mind that any healthy food eventually becomes ‘too much of a good thing,’ and that doesn’t stop the Dietary Guidelines from recommending foods such as fruits and vegetables. Like those foods, eggs have many documented health benefits and little potential for harm. Thus, I uphold my assertion that the Dietary Guidelines should encourage egg consumption, just as they encourage the consumption of other healthy foods.
By demonstrating that there is no link between dietary cholesterol and cardiovascular disease, I have proven that the USDA Dietary Guidelines have no basis for a limit on egg consumption. By demonstrating the significant need for more choline in the diet of the average American, I have proven that it might even be a good idea for the Guidelines to encourage egg consumption. The most obvious takeaway from this research is that you shouldn’t be afraid to eat eggs, but unfortunately, eggs are not the only food the Dietary Guidelines are wrong about. The inadequate scientific backing and exclusion of important nutrients that adversely affect the egg recommendations should lead us to question the credibility of the entire document. As I mentioned earlier, many prominent researchers and professionals are doing just that.
In light of this information, I encourage everyone to educate themselves on nutrition, and not simply take for granted that the Dietary Guidelines are correct. This is vitally important because the Dietary Guidelines dictate what children learn in school, what goes on food labels, and what registered dieticians are taught (USDA i). If the Guidelines are wrong, that misinformation is being dispensed through innumerable avenues all across the country. Until top-down change is achieved, each individual must take charge of their own knowledge and their own health.
Ballesteros MN, Cabrera RM, Saucedo Mdel S, Fernandez ML. Dietary cholesterol does not increase biomarkers for chronic disease in a pediatric population from northern Mexico. Am J Clin Nutr. 2004 Oct;80(4):855-61.
Caudill, Marie, et al. “Elevating Awareness and Intake of Choline: An Essential Nutrient for Public Health.” Nutrition Today 46.5 (2011): 235–241. Print.
DGAC. “Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010.” dietaryguidelines.gov. USDA, May 2010.
Djoussé L, Gaziano JM. Egg consumption in relation to cardiovascular disease and mortality: the Physicians’ Health Study. Am J Clin Nutr. 2008 Apr;87(4):964-9.
Fernandez, Maria L. “Rethinking Dietary Cholesterol.” Curr Opin Clin Nutr Metab Care 15 (2012): 117–121. Print.
Fernandez, Maria L. “Effects of Eggs on Plasma Lipoproteins in Healthy Populations.” The Royal Society of Chemistry 1 (2010): 156–160. Print.
Fernandez, Maria L, and Mariana Calle. “Revisiting Dietary Cholesterol Recommendations: Does the Evidence Support a Limit of 300 Mg/d?” Curr Atheroscler Rep 12 (2010): 377–383. Print.
Goodrow EF, Wilson TA, Houde SC, Vishwanathan R, Scollin PA, Handelman G, Nicolosi RJ. Consumption of one egg per day increases serum lutein and zeaxanthin concentrations in older adults without altering serum lipid and lipoprotein cholesterol concentrations. 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 elderly population given a dietary cholesterol challenge. J Nutr. 2005 Dec;135(12):2793-8.
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 Sep;47(6):287- 93.
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 study of egg consumption and risk of cardiovascular disease in men and women. JAMA. 1999 Apr 21;281(15):1387-94.
Jensen H, Batres-Marques S, Carriquiry A, Schalinske K. Choline in the Diets of the US Population: NHANES, 2003– 2004. Presented at the National Nutrient Data Bank Conference, 2007. FASEB J. 2007;21:lb219.
Kritchevsky SB, Kritchevsky D. Egg consumption and coronary heart disease: an epidemiologic overview. J Am Coll Nutr. 2000 Oct;19(5 Suppl):549S-555S.
Lecerf, Jean-Michel, and Michel de Lorgeril. “Dietary Cholesterol: From Physiology to Cardiovascular Risk.” British Journal of Nutrition 106.1 (2011): 6–14. Print.
McNamara DJ. The impact of egg limitations on coronary heart disease risk: do the numbers 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 HDL cholesterol in overweight men consuming a carbohydrate-restricted diet. J Nutr. 2008 Feb;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 disease incidence: Japan Public Health Center- based prospective study. Br J Nutr. 2006 Nov;96(5):921-8.
Natoli, Sharon, et al. “Unscrambling the Research: Eggs, Serum Cholesterol and Coronary Heart Disease.” Dietitians Association of Australia 64 (2007): 105–111. Print.
Qureshi AI, Suri FK, Ahmed S, Nasar A, Divani AA, Kirmani JF. Regular egg consumption does not increase the risk of stroke and cardiovascular diseases. Med Sci Monit. 2007 Jan;13(1):CR1-8.
Reaven GM, Abbasi F, Bernhart S, Coulston A, Darnell B, Dashti N, Kim H, Kulkarni K, 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):594-7.
Slavin, J. (2012). Dietary Guidelines: Are We on the Right Path? Nutrition Today, 47(5), 245–251. doi:10.1097/NT.0b013e31826c50af
U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th Edition, Washington, DC: U.S. Government Printing Office, December 2010.
Zeisel, Steven H., and Kerry-Ann da Costa. “Choline: An Essential Nutrient for Public Health.” Nutrition reviews 67.11 (2009): 615-23. Web.