Deuterium Content of Eggs: The White, the Yolk and What the Hen Drinks

Yavelle Journal · Diet & Lifestyle · 5 min read

Deuterium is a naturally occurring heavy isotope of hydrogen, measured in parts per million (ppm). Ordinary water sits at roughly 150 ppm, and foods land above or below that depending on what they are made of. An egg is worth looking at closely because its two halves are so different from one another.

The White and the Yolk Are Two Different Foods

The egg white, or albumen, is essentially water and protein, so there is no reason to expect it to sit far from the deuterium level of the water the hen drinks. The yolk is where the fat is, and fat is the macronutrient this literature places lowest on the deuterium scale. On composition alone, you would expect the yolk to sit below the white.

The measured figures follow that expectation. Both parts appear in the food deutenomics dataset published by James C. Lech and László G. Boros, with the measurements performed at the Vrije Universiteit Amsterdam.

Source: Lech & Boros, Deutenomics of Food (see references). Figures describe the specific samples tested.

That is a difference of 20 ppm between the two halves of the same egg, and it is the most interesting thing about an egg on this scale. It is a compositional fact and nothing more: the fat-bearing part measured lower than the water-and-protein part, which is what the macronutrient pattern would predict.

What the Hen Drinks Ends Up in the Egg

In a feeding study summarised in a 2024 scoping review in Metabolomics, laying hens had their normal drinking water replaced with 25 ppm deuterium-depleted water, and the deuterium content of the albumen and the yolk of their eggs was reported to fall over a 42-day period (Korchinsky et al., 2024). That is a separate source from the dataset above, and the review does not report the study's per-part ppm values in a form we can quote, so we do not print them. The figures in the table are ordinary eggs, not eggs from that study.

These are findings in animals and have not been demonstrated in people. They describe how deuterium moves through the food chain: what the hen drinks passes into what it lays. That is a statement about the composition of an egg and nothing more.

Duck Eggs

Duck eggs have a proportionally larger, fattier yolk relative to the white than chicken eggs do. If the yolk is the lower-deuterium part, a larger fat fraction would be expected to pull the whole-egg figure down. That follows from the composition; we are not aware of a published measurement comparing the two birds directly.

What the Hen Eats Matters Too

Just as an animal's feed shapes the deuterium in its meat and fat, a hen's diet shapes its eggs. Grain feed is rich in carbohydrate, and the same 2024 review reports lower deuterium content in grass-fed animals, below 130 ppm, against above 140 ppm in grain-fed animals (Korchinsky et al., 2024). Pasture-raised hens foraging on insects and greens sit at a different end of that range from birds on a grain ration. Source and husbandry introduce real variation, so treat any single figure as approximate.

The Practical Takeaway

The useful thing to know is compositional: the yolk is the fat-bearing part of the egg, and it measured 20 ppm below the white. If you are cooking with an eye to deuterium content, the whole egg keeps that part in; a white-only omelette leaves it out. That is a fact about what is in the food, not a recommendation about what anyone should eat.

How to Read These Figures

A few things are worth keeping in mind, and we would rather set them out than leave them implied.

These are measurements of specific samples, not category averages. Deuterium values in an egg vary with the water the hen drinks, its feed, the season and the farm, so a figure describes the egg that was tested rather than every carton on the shelf.

The dataset is a research compilation published by its authors rather than a peer-reviewed paper. It names the scientist who performed the measurements and the institution where they were performed, which is more than most circulating figures offer, but it does not report replicate counts or measurement uncertainty for these entries. Treat the numbers as indicative rather than exact.

And deuterium is only one measure. There are many other reasons to eat or not eat a given part of an egg, and none of them are settled by an isotope figure.

Where to Go Next

For the wider picture, our article on the deuterium content of common fats and oils explains why fat sits lowest of all, and our piece on grass-fed versus grain-fed meat covers why an animal's diet shapes what it produces.

References

1. Lech, J. C., & Boros, L. G. Deutenomics of Food: Food Deutenomics Data, Universal Nanomotor User Guide. Samples prepared by S. Dorfsman and P. Davelaar; measurements performed by J. C. Lech, Department of Physics and Astronomy, Physics of Living Systems, Vrije Universiteit Amsterdam, The Netherlands. Published by the authors at laszlogboros.com. Not peer reviewed.
2. Korchinsky, N., Davis, A. M., & Boros, L. G. (2024). Nutritional deuterium depletion and health: a scoping review. Metabolomics, 20(6), 117. https://doi.org/10.1007/s11306-024-02173-4
3. Répás, Győri, Buzás-Bereczki, & Boros. (2025). The biological effects of deuterium present in food. Discover Food, 5, 57. https://doi.org/10.1007/s44187-025-00327-4

This article is for general information. Reported deuterium values vary by source, feed and testing method and should be treated as approximate.

Yavelle 25ppm Deuterium-Depleted Water is a packaged food. It is not a therapeutic good and is not intended to diagnose, treat, cure or prevent any disease. Information on this page is general and is not medical advice. If you have a health condition or are undergoing treatment, speak with a qualified health practitioner.