The more cholesterol you eat, the less your liver makes. So for most people, an extra egg or two raises blood (low-density lipoprotein cholesterol, the so-called bad cholesterol) only slightly. The chapter on whether eggs raise blood cholesterol works through the numbers.
An egg is not one uniform blob of nutrition either. The white is almost all water and protein. The yolk is the micronutrient store: nearly all the fat-soluble vitamins, the choline, and the lutein sit there.
Eating only the whites keeps the protein and throws those micronutrients away. For most people, that is a poor trade.
A CLOSER LOOK
One egg, two nutrient profiles
The yolk contains protein too, not only the white.
1White
Mostly water and protein.
2Yolk
Most fat-soluble vitamins, choline and lutein are here.
Illustration for understanding; not to scale. Saved figures include explanations and sources.
Mechanism · White for protein, yolk for micronutrients
A large egg weighs about 50 g out of the shell: about 33 g of white and about 17 g of yolk. The white is bigger; the yolk is denser in nutrients.
The white has close to zero fat, cholesterol, and most micronutrients. The yolk holds nearly all of the egg's fat, cholesterol, fat-soluble vitamins (A, D, E, K), choline, lutein, and iron. Protein is not all in the white either: the yolk carries nearly half of it, and the chapter on protein and calories gives the numbers.
So eating only the white is a way to take the protein while avoiding the yolk's fat and cholesterol, at the cost of throwing away the egg's most valuable micronutrients. Fear of the yolk is often aimed at the wrong target, and the cholesterol chapter explains why.
The depth of a yolk's color mostly reflects carotenoids in the hen's feed. It is not a direct sign of better nutrition. A deep yellow yolk is not necessarily richer, and a pale one is not empty.
Chapter 2
Cheap, high-quality protein
An egg's calories come almost entirely from protein and fat; carbohydrate is close to zero. Protein is not all in the white: the yolk carries nearly half.
Cooking barely changes these numbers, but it does change how much you actually absorb. Cooked egg protein is far easier to digest than raw. So the claim that "raw is more nutritious" runs the wrong way.
Numbers · Calories and protein in one large egg
One large egg (50 g) has roughly 72 kcal, 6.3 g of protein, 5 g of fat, and close to 0 carbohydrate. The protein is split almost evenly between white and yolk: about 3.6 g in the white and about 2.7 g in the yolk. Eating only the white does not get you all the protein.
Eggs are low in energy density, and a gram of egg protein usually costs less than a gram from meat, fish, or whey powder. That is the core reason eggs work as an everyday protein source (see Protein & Amino Acids).
What cooking changes is digestibility. A human study that traced the protein with stable isotopes (Evenepoel 1998) found that about 91% of cooked egg protein was digested and absorbed, against only about 51% of raw. Heat unfolds the protein so digestive enzymes can cut it. So raw eggs are not more nutritious: you swallow the same grams, but nearly half less of it is actually absorbed.
Chapter 3
Choline and vitamins in the yolk
Egg protein is often used as the yardstick for protein quality: its amino-acid pattern is close to what people need, so almost all of what you eat can be used by the body.
The micronutrients sit almost entirely in the yolk. The biggest hidden loss from eating only the whites is choline, which matters especially for the fetal brain during pregnancy. Vitamin B12, vitamin D, and lutein also live in the yolk. Lutein dissolves in fat, and the yolk's own fat is its natural carrier.
Numbers · Choline, B12 and vitamin D in the yolk
Eggs are nutrition's reference protein: their amino-acid pattern closely matches the pattern people need, their biological value is very high, and they are often used as the yardstick in protein-quality scores (see Protein & Amino Acids).
The micronutrients sit almost entirely in the yolk:
Choline: about 147 mg per egg, almost all in the yolk. Eggs are one of the most efficient natural sources of dietary choline, and it matters especially for fetal brain development during pregnancy. This is the biggest hidden loss from eating only the whitesVitamin B12 (Vitamin B12): in natural foods it comes mainly from animal foods, plus fortified foods; the yolk is one of those sourcesVitamin D (Vitamin D): one of the few natural food sources, concentrated in the yolkRiboflavin B2 (Riboflavin) and selenium: involved in energy metabolism and in antioxidant enzymes, respectivelyBiotin B7 (Biotin): plentiful in the yolk, but raw egg white contains a protein called avidin that binds it; the chapter on choosing and cooking explains how heat undoes that
Evidence · Is lutein from eggs better absorbed?
Eggs also carry two carotenoids, lutein and zeaxanthin. They concentrate in the macula of the retina and are linked to eye health.
A small crossover trial (Chung 2004, in a small group of healthy men) had the same people take four sources in turn, each giving a similar amount of lutein: a lutein supplement, a lutein-ester supplement, spinach, and lutein-enriched eggs. Blood lutein rose most after the eggs; the other three did not differ from one another. Two cautions: the trial used enriched eggs, not ordinary ones, and the paper's abstract does not give a reason.
The yolk's fat is a plausible explanation. Lutein is fat-soluble and crosses the gut wall better when fat comes along, and the yolk packs the nutrient and its carrier into the same bite. That step is reasoned from the mechanism; this trial did not measure it directly. Eat only the whites, and both carotenoids are thrown away too.
Chapter 4
What's missing · how to pair
Eggs contain almost no vitamin C, dietary fiber, or carbohydrate. An all-egg breakfast is short on exactly those three.
The yolk does contain iron, but a phosphoprotein in the yolk binds it, so little is absorbed, and eggs mildly reduce the iron you absorb from other foods in the same meal. Eggs are an inefficient way to get iron.
In practice · What to pair it with; get iron elsewhere
An all-egg breakfast is short on fiber, vitamin C, and slowly digested carbohydrate. Add a whole-grain staple for carbohydrate and fiber, and vegetables or fruit for vitamin C and potassium.
Iron deserves its own note. The yolk contains iron, but its phosphoprotein binds it and lowers absorption, and eggs also mildly reduce iron absorption from other foods in the same meal. People who are short of iron do better relying on red meat and organ meats, or on plant iron eaten in the same meal as foods rich in vitamin C.
One more pairing point concerns fat-soluble nutrients. Lutein and vitamin D both need fat to be absorbed well, and the yolk brings its own fat, so eating the whole egg makes more sense for absorption than eating the white alone.
Chapter 5
Do eggs raise blood cholesterol?
Most of the cholesterol in your body is made by your liver, not eaten. When you eat a bit more, the liver makes a bit less; this is called negative feedback. So the cholesterol in food and the (low-density lipoprotein cholesterol, the so-called bad cholesterol) in your blood are not the same thing.
For most people, an extra egg or two raises LDL only slightly; about a quarter of people respond more strongly. Saturated and trans fats push LDL up more than the yolk does. As for eggs and heart disease, studies of large populations do not agree, and both sides are worth seeing.
Mechanism · How the liver dials cholesterol back
"Eggs are high in cholesterol, so heart patients cannot eat them" has circulated for decades. Set the mechanism down first, then see why the guidelines changed their minds.
One large yolk holds about 186 mg of dietary cholesterol. Older US dietary guidelines set a cap of less than 300 mg a day. In 2015 the US Dietary Guidelines Advisory Committee (DGAC) removed it, concluding that the evidence does not support treating dietary cholesterol itself as a nutrient of concern.
When you eat more cholesterol, the liver makes correspondingly less, but the dial does not turn all the way: for most people an extra egg or two raises only slightly. About a quarter of people are hyper-responders (a review by Fernandez 2012), whose LDL rises more clearly after eating cholesterol. Their (high-density lipoprotein cholesterol, the so-called good cholesterol) often rises too, so the ratio between the two stays roughly the same. But a rise in HDL cannot be used to cancel out a rise in LDL: HDL behaves more like a marker of risk than an active protector.
So dietary cholesterol is not blood LDL. What pushes LDL harder is usually not the yolk.
Evidence · The bacon moves LDL more than the yolk
A 2020 science advisory from the American Heart Association (AHA) states that saturated and trans fats affect blood more than cholesterol in food does. In other words, with a plate of bacon and eggs, the thing really pushing LDL up is more likely the bacon than the yolk.
That does not mean you can eat unlimited eggs. It means putting the worry where the needle actually moves: the saturated and trans fat in the side dishes, and the shape of the whole meal, deserve more attention than the 186 mg of cholesterol in the yolk.
Evidence · Two sets of cohort studies disagree
One honest caveat: do not pick only one paper. Both studies below are cohort studies (they follow a large group of people for years and look at what happens to those who eat more), so they show associations and cannot show that eggs caused anything.
Zhong 2019 pooled several US cohorts and found that the more eggs and dietary cholesterol people ate, the higher their risk of cardiovascular disease (), a dose-dependent association. Drouin-Chartier 2020 analyzed three large US cohorts and updated a of all the cohorts: about one egg a day was not associated with cardiovascular risk. Evidence in people with diabetes is still mixed, and current advice leans toward moderate intake judged within the whole diet.
Both are real human evidence, and they point in different directions. Keeping Zhong and hiding Drouin-Chartier, or the reverse, is making a dishonest choice for the reader. People with diabetes or established cardiovascular disease should keep eggs moderate, judge them within the whole diet, and check with a doctor if needed. This is not medical advice and does not replace a doctor's judgment of your situation.
Raw egg white has two problems: its protein is harder to digest, and a protein in it called avidin locks up biotin (vitamin B7). Heat denatures avidin, and both problems go away.
The answer to Salmonella is also heat: cook until the white and the yolk are both set. Older adults, pregnant women, young children, and people with weakened immunity should not eat runny or raw eggs. Labels such as free-range and organic mostly describe how the hens are raised, not a big nutritional difference.
In practice · What labels and shell color tell you
Labels such as cage-free, free-range, omega-3 enriched, and organic are mainly about how the hens were raised and fed. They do not mean the eggs win on nutrition across the board. Only omega-3 enriched eggs show a clearly measurable nutritional difference. Free-range eggs may run a little higher in vitamin D because the hens get more sun, but the difference varies with how the hens are kept. Whether the shell is white or brown reflects only the breed of hen and has nothing to do with nutrition.
Safety · Cook until set, and how many a day
Eggs can carry Salmonella. Keep them refrigerated. Cooking until both the white and the yolk are set kills it. Older adults, pregnant women, young children, and people with weakened immunity should avoid runny and raw eggs (including homemade mayonnaise). Wash your hands after handling raw eggs.
Raw egg white has two further problems. Its digestibility is only about half that of cooked egg. And its avidin binds biotin (B7) tightly, so eating large amounts of raw egg white over a long time can cause biotin deficiency. Heat denatures and inactivates avidin, and the problem disappears. The digestibility numbers in the chapter on protein and calories describe the same thing.
How many: for most healthy people, 1-2 whole eggs a day is reasonable, and there is no evidence that you need to throw the yolk away. People with diabetes or established cardiovascular disease should keep eggs moderate, judge them within the whole diet, and check with a doctor if needed. This is general education and does not replace medical advice.
References · 14
U.S. Department of Agriculture, Agricultural Research Service. (2019). FoodData Central: Egg, whole / yolk / white, raw, fresh. One large egg ~72 kcal, 6.3 g protein, 5 g fat; yolk ~186 mg cholesterol and ~147 mg choline. fdc.nal.usda.gov
Evenepoel, P., Geypens, B., Luypaerts, A., Hiele, M., Ghoos, Y., & Rutgeerts, P. (1998). Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques. The Journal of Nutrition, 128(10), 1716-1722. Cooked egg protein was ~91% digestible vs ~51% raw. 10.1093/jn/128.10.1716
National Institutes of Health, Office of Dietary Supplements. (2022). Choline — Fact Sheet for Health Professionals. Fact sheet (updated June 2, 2022; Wayback snapshot 21 September 2026): AIs 550 mg/day men, 425 women, 450 pregnancy, 550 lactation; premenopausal women might need less dietary choline because estrogen induces the gene (PEMT) for choline biosynthesis, although at least 40% of women of childbearing age carry a polymorphism that makes it insensitive to estrogen; prenatal supplements typically contain little if any choline; Table 2: beef liver, 3 ounces, 356 mg; egg, 1 large, 147 mg; beef top round, 3 ounces, 117 mg (fact sheet). ods.od.nih.gov/factsheets/Choline-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. (2024). Vitamin B12 — Fact Sheet for Health Professionals. Fact sheet (updated July 2, 2025; Wayback snapshot 20 September 2026): multivitamin/mineral supplements typically contain 5 to 25 mcg B12, B-complex products 50 to 500 mcg, B12-only supplements typically 500 to 1,000 mcg; absorption is only about 2% at 500 mcg and 1.3% at 1,000 mcg; a 2018 Cochrane review of 3 RCTs (153 participants) compared very high oral doses (1,000-2,000 mcg) with intramuscular B12; high oral doses (e.g. 1,000 mcg/day) might be equally effective in Crohn's disease and appear as effective as hydroxocobalamin injections after Roux-en-Y bypass. These are product contents and trial doses; the sheet gives no recommended daily supplement range (fact sheet). ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. (2024). Vitamin D — Fact Sheet for Health Professionals. Fact sheet (updated June 27, 2025; Wayback snapshot 20 September 2026): 25(OH)D below 30 nmol/L (12 ng/mL) is associated with deficiency, 30 to below 50 nmol/L is generally considered inadequate, 50 nmol/L (20 ng/mL) or more is sufficient for most people, and above 125 nmol/L (50 ng/mL) can be associated with adverse effects; RDA 600 IU (15 mcg) to age 70 and 800 IU (20 mcg) above 70; adult UL 4,000 IU (100 mcg); older people and people with darker skin (more melanin) make less vitamin D from sunlight (fact sheet). ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
National Institutes of Health, Office of Dietary Supplements. (2021). Selenium — Fact Sheet for Health Professionals. Table 2: Brazil nuts, 1 ounce (6-8 nuts), 544 mcg selenium (989% DV); the text says Brazil nuts contain 68-91 mcg per nut and could cause selenium toxicity if consumed regularly, and that values from other analyses vary widely. The version read carries 'Updated: April 15, 2024' (Wayback Machine snapshot of 31 December 2024), newer than the 2021 date above (fact sheet, read 2026-09-24). The September 4, 2025 update (Wayback snapshot 19 September 2026) adds: the body absorbs up to about 90% of selenium from selenomethionine, selenium-enriched yeast, selenite and selenate; selenium-only supplements typically contain 100 to 400 mcg; Keshan disease, an endemic cardiomyopathy first identified in 1935 in low-selenium parts of China, fell dramatically after selenium intervention trials in the 1970s-1990s; in 2017 the American Thyroid Association issued a weak recommendation against selenium supplements for TPOAb-positive pregnant women (fact sheet). ods.od.nih.gov/factsheets/Selenium-HealthProfessional
Chung, H. Y., Rasmussen, H. M., & Johnson, E. J. (2004). Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. The Journal of Nutrition, 134(8), 1887-1893. Egg lutein, packaged with fat, is absorbed more efficiently than from spinach. Crossover study in 10 healthy men: 9 days each of a lutein supplement, a lutein-ester supplement, spinach and lutein-enriched egg, each giving 6 mg lutein (5.5 mg for the ester). The dose-adjusted serum lutein response was higher after egg than after the other three sources, which did not differ from each other; the abstract gives no reason such as fat content (abstract, PMID 15284371). 10.1093/jn/134.8.1887
Carson, J. A. S., Lichtenstein, A. H., Anderson, C. A. M., Appel, L. J., Kris-Etherton, P. M., Meyer, K. A., et al. (2020). Dietary cholesterol and cardiovascular risk: A science advisory from the American Heart Association. Circulation, 141(3), e39-e53. Saturated and trans fats raise LDL more than dietary cholesterol itself. 10.1161/CIR.0000000000000743
Fernandez, M. L. (2012). Rethinking dietary cholesterol. Current Opinion in Clinical Nutrition and Metabolic Care, 15(2), 117-121. Dietary cholesterol challenges raise LDL in people more sensitive to it (about one-quarter of the population); HDL also rises, so the LDL/HDL ratio is maintained. 10.1097/MCO.0b013e32834d2259
Zhong, V. W., Van Horn, L., Cornelis, M. C., Wilkins, J. T., Ning, H., Carnethon, M. R., et al. (2019). Associations of dietary cholesterol or egg consumption with incident cardiovascular disease and mortality. JAMA, 321(11), 1081-1095. A pooled analysis that did find a dose-dependent association — included to present the evidence honestly as mixed. 10.1001/jama.2019.1572
Drouin-Chartier, J. P., Chen, S., Li, Y., Schwab, A. L., Stampfer, M. J., Sacks, F. M., et al. (2020). Egg consumption and risk of cardiovascular disease: three large prospective US cohort studies, systematic review, and updated meta-analysis. BMJ, 368, m513. Moderate egg intake (~1/day) was not associated with cardiovascular risk in the updated meta-analysis (~1.72M participants). 10.1136/bmj.m513
