Food · Meat & Seafood · 禽蛋
Eggs
参考级完全蛋白 + 胆碱冠军 · 胆固醇误区: 肝脏负反馈, 多数人不是高反应者 · 蛋黄是营养精华, 别只吃蛋清
Story path
- 1Eggs · one cell's nutrient kitEggs · one cell's nutrient kit
- 2Macros · cheap high-quality proteinMacros · cheap high-quality protein
- 3Rich in · the reference protein + choline championRich in · the reference protein + choline champion
- 4What's missing · how to pairWhat's missing · how to pair
- 5Headline · the dietary-cholesterol mythHeadline · the dietary-cholesterol myth
- 6How to choose · cook · how manyHow to choose · cook · how many
Chapter 1
Eggs · one cell's nutrient kit
Eggs · one cell's nutrient kit
Eggs are one of the few natural foods that come close to nutritionally complete on their own. A large egg is about 50 g shelled, and the white and yolk have a clear division of labour that explains every trade-off later.
The white (about 33 g) is almost entirely water and protein, with near-zero fat, cholesterol, and most micronutrients. The yolk (about 17 g) is the dense part: nearly all the fat, cholesterol, fat-soluble vitamins (A, D, E, K), choline, lutein, and iron live there.
So the popular 'egg-whites only' habit is really about taking the protein while skipping the yolk's fat and cholesterol — at the cost of throwing away the egg's most valuable micronutrients. For most people that's a poor trade, unpacked later.
Yolk colour mostly reflects carotenoids in the hen's feed rather than higher nutrition per se.
The white (about 33 g) is almost entirely water and protein, with near-zero fat, cholesterol, and most micronutrients. The yolk (about 17 g) is the dense part: nearly all the fat, cholesterol, fat-soluble vitamins (A, D, E, K), choline, lutein, and iron live there.
So the popular 'egg-whites only' habit is really about taking the protein while skipping the yolk's fat and cholesterol — at the cost of throwing away the egg's most valuable micronutrients. For most people that's a poor trade, unpacked later.
Yolk colour mostly reflects carotenoids in the hen's feed rather than higher nutrition per se.
Chapter 2
Macros · cheap high-quality protein
Macros · cheap high-quality protein
One large egg (50 g) is roughly 72 kcal, 6.3 g protein, 5 g fat, near-zero carbohydrate. Protein is split fairly evenly: about 3.6 g in the white, 2.7 g in the yolk — eating only the white does not capture all the protein.
Low energy density plus extremely low cost per gram of protein is why eggs work so well as an everyday protein source (dive: protein). The price per gram usually beats meat, fish, and whey.
Cooking barely changes the macros but changes digestibility: cooked egg protein is absorbed at about 91% versus about 51% for raw, because heat unfolds the protein for enzymes. So 'raw eggs are more nutritious' is backwards.
Low energy density plus extremely low cost per gram of protein is why eggs work so well as an everyday protein source (dive: protein). The price per gram usually beats meat, fish, and whey.
Cooking barely changes the macros but changes digestibility: cooked egg protein is absorbed at about 91% versus about 51% for raw, because heat unfolds the protein for enzymes. So 'raw eggs are more nutritious' is backwards.
Chapter 3
Rich in · the reference protein + choline champion
Rich in · the reference protein + choline champion
Eggs are nutrition's 'reference protein': their amino-acid pattern closely matches human needs and their biological value is very high, often used as the yardstick in protein-quality scores (dive: protein). Almost all the protein you eat is usable.
Micronutrient highlights:
Choline (choline): about 147 mg per egg, almost all in the yolk. Eggs are one of the most efficient natural sources, and it matters especially for fetal brain development in pregnancy — the biggest hidden loss of 'egg-whites only'Vitamin B12 (vitamin-b12): animal-food exclusiveVitamin D (vitamin-d): one of the few natural food sources, concentrated in the yolkRiboflavin B2 (riboflavin-b2), selenium (selenium): antioxidant and energy metabolismBiotin B7 (biotin-b7): rich in the yolk — but avidin in raw egg white binds biotin (see special-knowledge)
Eggs also carry lutein and zeaxanthin, carotenoids that concentrate in the retinal macula; packaged with yolk fat, they absorb better than those from vegetables.
Micronutrient highlights:
Choline (choline): about 147 mg per egg, almost all in the yolk. Eggs are one of the most efficient natural sources, and it matters especially for fetal brain development in pregnancy — the biggest hidden loss of 'egg-whites only'Vitamin B12 (vitamin-b12): animal-food exclusiveVitamin D (vitamin-d): one of the few natural food sources, concentrated in the yolkRiboflavin B2 (riboflavin-b2), selenium (selenium): antioxidant and energy metabolismBiotin B7 (biotin-b7): rich in the yolk — but avidin in raw egg white binds biotin (see special-knowledge)
Eggs also carry lutein and zeaxanthin, carotenoids that concentrate in the retinal macula; packaged with yolk fat, they absorb better than those from vegetables.
Chapter 4
What's missing · how to pair
What's missing · how to pair
Eggs are well-rounded but not complete: almost no vitamin C, dietary fibre, or carbohydrate. So an all-egg breakfast is short on fibre, vitamin C, and slow carbs: add a whole-grain base for carbs and fibre, add vegetables or fruit for vitamin C and potassium.
Iron deserves a note: the yolk contains iron, but its phosphoprotein binds iron and lowers absorption, and eggs also mildly inhibit iron absorption from other foods. So 'eggs for iron' is inefficient; iron-deficient people should lean on red meat, organ meats, or plant iron paired with vitamin C.
One more pairing point: fat-soluble nutrients — lutein and vitamin D — need fat to absorb well, and the yolk brings its own fat, so eating the whole egg is more sensible than the white alone.
Iron deserves a note: the yolk contains iron, but its phosphoprotein binds iron and lowers absorption, and eggs also mildly inhibit iron absorption from other foods. So 'eggs for iron' is inefficient; iron-deficient people should lean on red meat, organ meats, or plant iron paired with vitamin C.
One more pairing point: fat-soluble nutrients — lutein and vitamin D — need fat to absorb well, and the yolk brings its own fat, so eating the whole egg is more sensible than the white alone.
Chapter 5
Headline · the dietary-cholesterol myth
Headline · the dietary-cholesterol myth
'Eggs are high in cholesterol, so heart patients can't eat them' has circulated for decades. Walked through the evidence, it's weaker than it sounds.
One large yolk holds about 186 mg of dietary cholesterol. Older US guidelines set a '< 300 mg/day' cap, but in 2015 the Dietary Guidelines Advisory Committee removed it, concluding the evidence does not support treating dietary cholesterol itself as a 'nutrient of concern'.
The mechanism is the point. Most of the body's cholesterol is made by the liver, not eaten. When you take in more, the liver makes correspondingly less — a homeostatic negative feedback. For roughly two-thirds of people (low responders), an extra egg or two barely moves blood LDL. About a third are 'hyper-responders' whose LDL rises somewhat — but HDL often rises alongside, so the net cardiovascular change is more complex than LDL alone.
More importantly, priorities: the AHA's 2019 science advisory holds that saturated and trans fats move blood LDL more than dietary cholesterol does. With bacon and eggs, the thing really raising LDL is more likely the bacon than the yolk.
One honest caveat: cohort evidence in people with diabetes is mixed (Zhong 2019 found an association; Drouin-Chartier 2020 found none overall). So for diabetics, current guidance leans toward 'moderate, in the context of the whole diet'. This isn't medical advice; check with your doctor if it applies to you.
One large yolk holds about 186 mg of dietary cholesterol. Older US guidelines set a '< 300 mg/day' cap, but in 2015 the Dietary Guidelines Advisory Committee removed it, concluding the evidence does not support treating dietary cholesterol itself as a 'nutrient of concern'.
The mechanism is the point. Most of the body's cholesterol is made by the liver, not eaten. When you take in more, the liver makes correspondingly less — a homeostatic negative feedback. For roughly two-thirds of people (low responders), an extra egg or two barely moves blood LDL. About a third are 'hyper-responders' whose LDL rises somewhat — but HDL often rises alongside, so the net cardiovascular change is more complex than LDL alone.
More importantly, priorities: the AHA's 2019 science advisory holds that saturated and trans fats move blood LDL more than dietary cholesterol does. With bacon and eggs, the thing really raising LDL is more likely the bacon than the yolk.
One honest caveat: cohort evidence in people with diabetes is mixed (Zhong 2019 found an association; Drouin-Chartier 2020 found none overall). So for diabetics, current guidance leans toward 'moderate, in the context of the whole diet'. This isn't medical advice; check with your doctor if it applies to you.
Chapter 6
How to choose · cook · how many
How to choose · cook · how many
Choosing: labels like 'cage-free / free-range / omega-3 enriched / organic' are mostly about how the hen was raised and fed, not a nutritional landslide. Only omega-3 enriched eggs show a clearly measurable difference; pasture eggs tend to run a little higher in lutein and vitamin D. Shell colour (white vs brown) reflects hen breed and has nothing to do with nutrition.
Safety is the focus. Eggs can carry Salmonella: refrigerate; cook until both white and yolk are set, which kills it; elderly, pregnant, young children, and immunocompromised people should avoid runny and raw eggs (soft-yolk eggs, homemade mayonnaise); wash hands after handling raw eggs.
Raw egg white has two problems: digestibility is only about half, and its avidin binds biotin (B7), so eating large amounts raw long-term can cause biotin deficiency — heat denatures avidin and the problem disappears.
How many: for most healthy people, 1-2 whole eggs a day is reasonable, with no evidence requiring you to discard the yolk. People with diabetes or established cardiovascular disease should keep it moderate and in the context of the whole diet, checking with a doctor if needed. This page is educational, not a substitute for medical advice.
Safety is the focus. Eggs can carry Salmonella: refrigerate; cook until both white and yolk are set, which kills it; elderly, pregnant, young children, and immunocompromised people should avoid runny and raw eggs (soft-yolk eggs, homemade mayonnaise); wash hands after handling raw eggs.
Raw egg white has two problems: digestibility is only about half, and its avidin binds biotin (B7), so eating large amounts raw long-term can cause biotin deficiency — heat denatures avidin and the problem disappears.
How many: for most healthy people, 1-2 whole eggs a day is reasonable, with no evidence requiring you to discard the yolk. People with diabetes or established cardiovascular disease should keep it moderate and in the context of the whole diet, checking with a doctor if needed. This page is educational, not a substitute for medical advice.