--- topic: "Eggs" title: "The Perfect Food" order: 1 description: "Why eggs are one of the most nutrient-dense foods you can buy, what the evidence says about the old cholesterol warning, and how little range access changes an egg" question: "Are eggs healthy, or do they raise your cholesterol?" answer: "For most healthy people, eggs are unlikely to raise blood cholesterol meaningfully, and they supply complete protein, choline, lutein and zeaxanthin." actions: - "Eat whole eggs, yolk included: it holds the choline most people fall short on [2]." - "Healthy adults can eat about 3 eggs a day; most research found no harm to cardiovascular markers [1]." - "Choose pasture-raised eggs (deep orange yolks) for more omega-3, vitamin A and vitamin E; \"cage-free\" alone does not mean pasture [4]." cautions: - "A minority of people (\"hyper-responders\") see LDL cholesterol rise with eggs; if you have heart-disease risk, check your lipids with your doctor [1]." - "Findings apply to healthy adults; not a substitute for medical advice if you have high cholesterol, diabetes or heart disease." confidence: 3 confidenceNote: "Based on reviews of dietary cholesterol, choline and carotenoid research plus one egg-composition study; no individual trial or long-term cohort is described." evidenceSummary: newestStudyYear: 2018 references: - id: "1" pmid: "29596318" title: "Dietary Cholesterol, Serum Lipids, and Heart Disease: Are Eggs Working for or Against You?" authors: "Blesso CN, Fernandez ML" year: 2018 journal: "Nutrients" - id: "2" pmid: "19906248" title: "Choline: An Essential Nutrient for Public Health" authors: "Zeisel SH, da Costa KA" year: 2009 journal: "Nutrition Reviews" - id: "3" pmid: "23571649" title: "Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health" authors: "Abdel-Aal el-SM, Akhtar H, Zaheer K, Ali R" year: 2013 journal: "Nutrients" - id: "4" pmid: "21673178" title: "Comparison of fatty acid, cholesterol, and vitamin A and E composition in eggs from hens housed in conventional cage and range production facilities" authors: "Anderson KE" year: 2011 journal: "Poultry Science" --- Eggs have been unfairly demonized for decades. The old advice to limit eggs because of cholesterol assumed that eating cholesterol raises blood cholesterol — but in controlled studies about two-thirds of people see only a minimal change [1], and large population studies have found only weak links between egg intake and heart disease [1]. Meanwhile, a single egg delivers complete protein with all essential amino acids, plus choline, B vitamins, selenium, and fat-soluble vitamins packed into the yolk. At roughly 70 calories each, eggs are among the most nutrient-dense foods per dollar. If you eat only the whites, you leave behind the yolk, where the choline, lutein, and fat-soluble vitamins are. The cholesterol worry dates back to oversimplified dietary guidelines from the 1960s-70s. A large egg contains about 186 mg of cholesterol, and the old recommendation was to stay under 300 mg/day. But large-scale epidemiological studies have found only tenuous associations between egg intake and cardiovascular disease risk, and in well-controlled studies roughly two-thirds of people have only a minimal response in blood cholesterol to eggs [1]. The 2015-2020 Dietary Guidelines for Americans dropped the 300 mg/day cap. **Complete protein:** Egg protein has long been used as the reference standard for protein quality, with a biological value of 100. All nine essential amino acids are present in proportions your body can readily use. One large egg provides about 6 grams of protein split between the white and yolk. **Choline** is perhaps the most underappreciated nutrient in eggs. Eggs and meats are rich sources of choline in the North American diet, providing up to 430 mg per 100 g, yet average intakes for older children, men, women, and pregnant women are far below the adequate intake level [2]. Choline is involved in everything from cell structure to neurotransmitter synthesis, and low intake is thought to affect liver disease, atherosclerosis, and possibly neurological disorders [2]. **Lutein and zeaxanthin** are carotenoid pigments that give foods such as eggs their yellow or orange color. They are the main pigments of the macula of the eye, where they protect against damage from blue light and scavenge reactive oxygen species, and they have been linked with a lower risk of age-related macular degeneration and cataracts [3]. **Pasture-raised vs conventional** — the label promises more than the data show. Labels such as "cage-free," "free-range," and "pasture-raised" are defined differently and are not a guarantee of nutrient content. In a study that followed 500 hens of one breed, hatched together and managed identically except that some had access to a range, eggs from the range hens had only slightly more omega-3 fatty acids (0.17% against 0.14% of the egg) and more total fat, while cholesterol did not differ and vitamin A and vitamin E levels were not affected by range access [4]. The laboratory that did the analysis also had a significant effect on the measured content of every nutrient except cholesterol, so small differences between eggs should not be over-read [4]. **How many eggs?** Large observational studies find only weak associations between egg intake and cardiovascular disease [1]. In controlled studies about two-thirds of people show little change in blood cholesterol when they eat eggs, while the rest — sometimes called "hyper-responders" — see both LDL and HDL cholesterol rise, typically keeping a similar LDL/HDL ratio [1]. How many eggs suit you depends on your own risk. See [Eggs, Cholesterol, and Heart Health](/eggs/eggs-cholesterol-and-heart-health) for a closer look at the cohort data and who should be more careful. Blesso and Fernandez (2018) reviewed how eggs and dietary cholesterol affect serum cholesterol, lipoprotein particle profiles, and HDL metabolism [1]. Large-scale epidemiological studies have found only tenuous associations between egg intake and cardiovascular disease risk. In well-controlled clinical studies the effect of the dietary cholesterol in eggs on serum lipids was highly variable: about two-thirds of the population had only minimal responses, while those with a significant response increased both LDL and HDL cholesterol, typically with the LDL/HDL ratio maintained. The review points to potentially favorable effects of egg intake on lipoprotein particle profiles and on HDL function. It also notes that recent drug trials aimed at raising HDL cholesterol failed to reduce cardiovascular events, so it is unclear whether the HDL rise seen with chronic egg intake is beneficial, and that more research on HDL function in humans is warranted. Zeisel and da Costa (2009) summarized choline's status as an essential nutrient, officially recognized by the Institute of Medicine in 1998 [2]. The dietary requirement varies widely between people, partly because of common genetic polymorphisms. Choline has roles from cell structure to neurotransmitter synthesis, and choline deficiency is now thought to affect diseases such as liver disease, atherosclerosis, and possibly neurological disorders. Eggs and meats are rich sources of choline in the North American diet, but mean intakes for older children, men, women, and pregnant women are far below the adequate intake level, and the authors argue that dietary guidance should be developed to encourage the intake of choline-rich foods. Abdel-Aal et al. (2013) reviewed the dietary sources of lutein and zeaxanthin and their role in eye health [3]. These carotenoids are the main pigments of the yellow spot of the human retina, where they protect the macula from damage by blue light, improve visual acuity, and scavenge harmful reactive oxygen species. The review reports that their role in eye health is well established from epidemiological, clinical, and interventional studies and that they have been linked with reduced risk of age-related macular degeneration and cataracts. Eggs are among the foods that supply them, along with cantaloupe, corn, carrots, orange and yellow peppers, and fish. Anderson (2011) compared the nutrient content of free-range and cage-produced eggs, examining the effects of laboratory, production environment, and hen age [4]. A flock of 500 Hy-Line Brown layers was hatched at the same time and received the same care (vaccination, lighting, and feeding); the only difference was access to the range. The eggs were analyzed for cholesterol, n-3 fatty acids, saturated, monounsaturated, and polyunsaturated fat, and vitamins A and E (and β-carotene), and the same egg pool was split between four laboratories. Eggs from the range environment had more total fat (P < 0.05), monounsaturated fat (P < 0.05), and polyunsaturated fat (P < 0.001) than eggs from caged hens, and n-3 fatty acids were higher (P < 0.05) at 0.17% in range eggs versus 0.14% in cage eggs. Range access had no effect on cholesterol (163.42 and 165.38 mg per 50 g in eggs from caged and range hens, respectively), and vitamin A and E levels were not affected by husbandry; they were lowest in hens at 62 weeks of age. The laboratory had a significant effect on the measured content of every nutrient except cholesterol (total fat ranged from 6.76% to 8.88% across the four laboratories). This is one flock of one breed, so it does not support claims that pastured eggs carry several times more omega-3 or markedly more vitamin A or vitamin E than conventional eggs.