Eggs

Up to about one egg a day is fine for most healthy adults, ideally eaten with vegetables and whole grains rather than bacon and white toast. If you have diabetes or familial hypercholesterolaemia, an inherited cause of very high cholesterol, be more conservative and discuss it with your doctor.

The same egg looks different in different countries

Cohort studies of eggs and heart disease give different answers depending on where they were done. The clearest comparison comes from a 2022 meta-analysis that reported its results separately by region, per 50 g of egg a day — about one egg. The relative risk (RR) is the change in risk for each extra egg a day; the bracketed 95% confidence interval (CI) is the range where the true effect most plausibly lies, and when it crosses 1.0 the result is compatible with no effect.^[1]

The Asian row is often oversold as protective. It shows an absence of harm, not a benefit. A separate pooling of three large US cohorts alongside 28 others put the Asian estimate slightly on the protective side, about 8% lower risk (RR 0.92, 0.85–0.99), so the direction is uncertain and the size small either way.^[2]

A plausible explanation is the rest of the plate. In a Western diet an egg typically comes with bacon, sausage, white toast and butter; in a traditional Japanese diet, with rice, miso, fish and vegetables. The egg is identical; the meal is not. All of this is observational, so it cannot separate the egg from the company it keeps.

Any risk is small and rises gradually, with no threshold

A dose-response meta-analysis pooling cohorts by eggs per week tested for a bend in the curve on six outcomes and found none — there is no intake at which risk suddenly jumps.^[3]

Two of its results stand out:

• Cancer deaths. The one clearly positive overall finding: about 20% higher cancer death rates at the highest egg intakes versus the lowest (RR 1.20, 95% CI 1.04–1.39, 13 studies), roughly 4% per extra egg a week.
• The US-versus-Asia split again. In US cohorts, overall death rates were about 18% higher (RR 1.18, 1.10–1.26) and cardiovascular death rates about 20% higher (1.20, 1.10–1.31) at the highest intakes, against slightly lower overall death rates in Asian cohorts (0.89, 0.80–0.99) — the same geographic pattern as above, in a second analysis.

Why the cholesterol in eggs barely moves your blood lipids

When healthy adults eat extra eggs, the liver makes less of its own cholesterol to compensate. A 2022 egg meta-analysis, citing earlier feeding-study work, puts the effect as real but small: each extra 100 mg a day of dietary cholesterol raises low-density lipoprotein (LDL, "bad") cholesterol by roughly 1.9 mg/dL (about 0.05 mmol/L) and high-density lipoprotein (HDL, "good") cholesterol by roughly 0.4 mg/dL.^[4]

The common add-on claim that the cholesterol ratio stays put is not settled. The pooled trial analysis behind the most-quoted figure, as summarised in a 2013 egg meta-analysis, reports the ratio of total to HDL cholesterol rising by about 0.02 units per 100 mg a day.^[5] A small movement, but a movement, not a wash.

Two small Japanese studies point the other way, reporting higher HDL cholesterol and less oxidised LDL after a month of one egg a day. Both come from the research group behind a 2026 review of eggs and health, and neither is large enough to settle it.^[6]

What the guidelines say, and who should be careful

The American Heart Association's 2019 advisory sets no numeric limit on dietary cholesterol at all and frames the question around the whole dietary pattern. It is generally read as allowing up to one whole egg a day for healthy adults, with more caution in diabetes and in familial hypercholesterolaemia.^[7]

Type 2 diabetes is where the caution has the most behind it. The same 2013 meta-analysis found a stronger link between eggs and cardiovascular disease in people who already had diabetes, and in five Western general-population cohorts of about 69,000 people, eating an egg a day or more went with about 42% more new type 2 diabetes than eating less than one a week (hazard ratio 1.42, 95% CI 1.09–1.86). Both findings are observational, diabetes was a secondary outcome in most of the studies, and the authors themselves caution that the result may not justify changing dietary advice.^[8]

Eggs and the brain: interesting, not a reason to eat more

Eggs are the richest food source of phosphatidylcholine, a choline-carrying fat that makes up roughly a third of the brain's phospholipids and that the body uses to make acetylcholine, the memory chemical most damaged in Alzheimer's disease.

In a crossover trial in 18 adults, choline taken as egg-yolk phospholipid raised blood choline about four times more than the same dose of a synthetic choline supplement — but the dose was roughly 20 times the choline in one egg, and the authors note it may have saturated the absorption pathway.^[9]

Whether that matters for the brain is unclear. In a Finnish cohort followed for 22 years, men in the highest quarter of dietary phosphatidylcholine intake had about 28% lower dementia risk, with a confidence interval running from 1% to 48% — real, but barely.^[10] It was observational and in men only.

What to do

1. Treat up to about one egg a day as fine if you are a healthy adult.
2. Mind the plate more than the egg. Eggs with vegetables and whole grains are a different meal from eggs with bacon, sausage and white toast.
3. Be more conservative with diabetes or familial hypercholesterolaemia, and talk it over with your doctor.
4. Don't eat extra eggs for your brain. The dementia signal is one cohort and barely clear of chance.

The wider picture on fats and cholesterol is on Dietary fats; how LDL cholesterol is managed is on Lipid management.

Further reading

• Zhao B et al. Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis. Circulation 2022.^[11]
• Mousavi SM et al. Egg Consumption and Risk of All-Cause and Cause-Specific Mortality: A Systematic Review and Dose-Response Meta-analysis of Prospective Studies. Advances in Nutrition 2022.^[12]
• Carson JAS et al. Dietary Cholesterol and Cardiovascular Risk: A Science Advisory From the American Heart Association. Circulation 2020.^[13]