A single large egg packs 6.3 grams of protein, about 5 grams of fat, and a surprisingly wide range of vitamins and minerals into just 71 calories. Few foods deliver this much nutritional variety in such a small, inexpensive package. Here’s a closer look at everything inside.
Protein and Fat
Protein is what most people associate with eggs, and for good reason. A large egg (about 50 grams) contains 6.3 grams of complete protein, meaning it includes all nine essential amino acids your body can’t make on its own. Roughly half that protein sits in the white and half in the yolk.
The fat content, about 5 grams per egg, lives almost entirely in the yolk. Most of that fat is unsaturated. The dominant fatty acid in egg yolk is oleic acid, the same heart-friendly monounsaturated fat found in olive oil, making up roughly 31 to 44 percent of the yolk’s total fat. Saturated fat accounts for about a third of the total, with the rest split between monounsaturated and polyunsaturated fats. Eggs do contain small amounts of omega-3 fatty acids, though the levels are modest unless the hens were fed an omega-3-enriched diet.
Carbohydrates are nearly absent. A whole egg has less than 1 gram, which is why eggs show up in so many low-carb meal plans.
Vitamins From A to K
The yolk is where the vitamin payload lives. It contains significant amounts of vitamins A, D, E, and K, plus several B vitamins. One egg provides about 10 percent of the daily value for vitamin D (around 41 IU), a nutrient many people fall short on, especially in winter months or with limited sun exposure. Eggs are one of the few non-fortified food sources of vitamin D.
Vitamin B12, which your body needs for nerve function and red blood cell production, is present at roughly 0.89 micrograms per 100 grams of egg. Since a large egg weighs about 50 grams, one egg gives you close to 0.45 micrograms, a meaningful contribution toward the daily target of 2.4 micrograms. Egg whites, by contrast, contain virtually none of these fat-soluble vitamins. If you’re eating only whites, you’re missing most of the vitamin content.
Key Minerals
Eggs supply several minerals that play essential roles in everyday body functions. Selenium, which supports your immune system and thyroid, is present in useful amounts. Iron and zinc, both concentrated in the yolk, help with oxygen transport and immune defense. Eggs also contain iodine, another mineral tied to thyroid health that many people don’t think about.
Calcium rounds out the mineral profile, again found primarily in the yolk rather than the white.
Choline: The Overlooked Nutrient
One of the most underappreciated things inside an egg is choline. The yolk is one of the richest food sources of this nutrient, which your body uses for brain development, nerve signaling, and maintaining healthy cell membranes. Most adults don’t get enough choline from their diet, and a single egg covers a large chunk of the daily recommendation (about 550 mg for men, 425 mg for women). Pregnant women need it for fetal brain development, making eggs a particularly valuable food during pregnancy.
Compounds That Protect Your Eyes
Egg yolks get their yellow-orange color from two pigments called lutein and zeaxanthin. These compounds accumulate in the retina, specifically in the macula, the part of your eye responsible for sharp central vision. Higher levels of these pigments are associated with a reduced risk of age-related macular degeneration, a leading cause of vision loss in older adults.
What makes eggs special here isn’t the quantity of lutein and zeaxanthin (leafy greens contain more) but the absorption rate. The fat in the yolk helps your body take up these pigments more efficiently than it would from vegetables alone. Research has shown that eating one egg per day increases blood levels of both lutein and zeaxanthin in older adults without negatively affecting cholesterol.
Yolk vs. White: What’s Where
The white and the yolk are nutritionally very different foods. A single egg white provides about 17 calories and 3.6 grams of protein, with virtually no fat or cholesterol. It’s mostly protein and water. The yolk delivers the remaining 3.6 grams of protein plus all the fat, all the cholesterol, and nearly all the vitamins and minerals. Vitamins A, D, E, K, the B complex, iron, zinc, choline, lutein, zeaxanthin, and essential fatty acids are all concentrated in the yolk.
Eating only egg whites is a strategy some people use to cut calories or avoid cholesterol, but it means giving up the most nutrient-dense part of the egg. For most people, the whole egg provides the better nutritional return.
Cholesterol in Context
A large egg contains about 186 milligrams of cholesterol, all in the yolk. For years, this made eggs a food people avoided. Current dietary guidelines take a softer stance. The Dietary Guidelines for Americans (2020-2025) include eggs as a core component of a healthy eating pattern, grouped with meats and poultry at a combined recommendation of 26 ounce-equivalents per week. No specific egg limit is set.
The shift happened because research increasingly shows that dietary cholesterol has a smaller effect on blood cholesterol than previously thought for most people. Saturated fat and trans fat in your overall diet have a bigger influence. That said, individual responses vary. Some people are more sensitive to dietary cholesterol than others, and those managing heart disease or diabetes may want to be more mindful of intake.
What the Hen Eats Matters
The nutrient profile of an egg isn’t fixed. It shifts based on what the hen was fed. Hens given feed enriched with flaxseed or fish oil produce eggs with measurably higher omega-3 fatty acid levels. Pasture-raised hens that eat insects and plants often produce yolks with more vitamin D and deeper-colored yolks, reflecting higher levels of lutein and zeaxanthin. Standard conventional eggs still contain the full range of nutrients described above, but the amounts of certain compounds, particularly omega-3s and fat-soluble vitamins, can vary depending on farming practices.