Is the vitamin B12 in the egg white or yolk?

October 26, 2025 •

3 min read

One large, hard-boiled egg can supply a substantial portion of the daily recommended intake for vitamin B12. However, a common misconception exists regarding which part contains this vital nutrient, leading many to ask: is the vitamin B12 in the egg white or yolk?

Quick Summary

The vast majority of vitamin B12 is concentrated within the nutrient-dense egg yolk. While the egg white contains only trace amounts, consuming the whole egg ensures you receive the full benefits of this essential vitamin.

Key Points

Concentration in the Yolk: Almost all of the vitamin B12 in an egg is contained within the yolk, not the white.
Yolk's Rich Nutrient Profile: The egg yolk is a powerhouse of micronutrients, including vitamins A, D, E, and K, as well as other B vitamins, choline, and minerals.
Egg White's Limited Role: While egg whites offer lean protein, they are not a significant source of vitamin B12 or other essential micronutrients.
Better Absorption from the Yolk: The vitamin B12 in the egg yolk is more easily absorbed by the body compared to the trace amounts found in the white.
Consume the Whole Egg for Benefits: To gain the full nutritional advantages of eggs, including the complete vitamin B12 intake, it is recommended to consume the entire egg rather than separating the white and yolk.
Heat and Absorption: Cooking eggs denatures certain proteins in the white that can inhibit B12 absorption, though the yolk remains the primary source.

The Nutrient-Dense Yolk: The Home of Vitamin B12

The vast majority of vitamin B12 is found in the egg yolk. The yolk is a nutritional powerhouse, containing fat-soluble vitamins A, D, E, and K, as well as B vitamins like B12 and folate. It's notable that per 100g, egg yolk has significantly more vitamin B12 than egg white. Consuming the whole egg is the best way to get B12 from this source.

The B12 in the yolk is also more bioavailable, meaning the body can absorb it better than the B12 in the white. This is partly due to proteins in the white that can hinder absorption. Eating the entire egg is key for increasing B12 intake from eggs.

The Mostly Protein Egg White: A Minimal Source

Egg whites are popular for their low calories and high protein, but they have far fewer micronutrients than the yolk. An egg white is mainly water (about 88%) and protein (about 10%), with minimal fat, cholesterol, or other nutrients. It contains a tiny, negligible amount of B12, making it an insignificant dietary source.

The white also contains avidin, a protein that can bind to biotin and prevent its absorption, although cooking neutralizes avidin. This highlights the difference in nutritional structure between the white and the yolk. Relying solely on egg whites will not provide a meaningful increase in vitamin B12.

The Comparison: Yolk vs. White

Here's a comparison of the key nutritional components of the yolk and white, based on data:


Nutrient	Egg Yolk (per 100g)	Egg White (per 100g)	Primary Purpose	Contribution to Diet
Vitamin B12	Significantly Higher	Trace amounts	Red blood cell formation, nerve function, DNA synthesis	Essential for meat and dairy consumers; vital for overall health.
Protein	Higher per gram, lower total volume per egg	Lower per gram, higher total volume per egg	Muscle repair and growth	Excellent source of high-quality, complete protein.
Fats	Rich source	Almost none	Energy, absorption of fat-soluble vitamins (A, D, E, K)	Healthy fats contribute to satiety and overall health.
Vitamins A, D, E, K	Exclusively Present	None	Vision, bone health, antioxidant properties	The yolk is one of the few natural food sources of vitamin D.
Cholesterol	Present	None	Cell membrane structure, hormone synthesis	Important for body functions, but some individuals may need to moderate intake.
Other B Vitamins	High levels of B2, B5, B9	Moderate levels of B2, B5, B3	Energy metabolism	Both contribute, but the yolk is richer in many B vitamins.
Minerals	Rich in iron, zinc, selenium	Smaller amounts of potassium, magnesium, selenium	Essential bodily functions	The yolk is a dense source of many critical minerals.

The Verdict: The Whole Egg Offers Full Nutritional Benefits

Eating only egg whites removes a large part of the egg's nutrition. The yolk contains most vitamins and minerals, including almost all the B12. Eating the whole egg provides a complete nutrient profile. Dietary cholesterol from eggs is less of a concern for most healthy people than once thought.

Individuals on specific diets should consult a healthcare professional. However, for the average person, consuming the whole egg offers a wider range of nutrients, including B12 and healthy fats that help absorb other vitamins.

Conclusion

To answer "is the vitamin B12 in the egg white or yolk?", the yolk is the main source. Egg whites offer lean protein but lack the dense vitamins and minerals of the yolk. Eating the whole egg is the best way to get its full benefits, especially vitamin B12.

Authoritative Resource for Further Reading

A study in The American Journal of Clinical Nutrition discusses how B12 absorption differs between egg white and yolk due to binding proteins.

Bioavailability and the Whole Egg

The way nutrients are absorbed is crucial. Different proteins in the white and yolk affect B12 bioavailability. Proteins in the white can interfere with absorption, but cooking denatures them. Still, the yolk is the superior source.

The Role of B12 in the Body

Vitamin B12 is essential for creating red blood cells and for nerve function. Deficiency can cause anemia, fatigue, memory issues, and nerve damage. Eggs, particularly the whole egg, are a convenient source of bioavailable B12.

Beyond B12: Other Key Yolk Nutrients

Besides B12, the yolk has other important nutrients:

Choline: A rich source for brain health and neurotransmitters.
Lutein and Zeaxanthin: Antioxidants that benefit eye health.
Fat-Soluble Vitamins: Healthy fats in the yolk help absorb vitamins A, D, E, and K.

Frequently Asked Questions

No, eating only egg whites will not directly cause a B12 deficiency on its own, especially if you get B12 from other sources. However, it will remove eggs as a significant source of B12 from your diet, making it necessary to get the nutrient from elsewhere.

Yes, research indicates that the vitamin B12 found in egg yolks is more readily absorbed by the body compared to the minimal amounts present in the egg white.

To get the maximum amount of vitamin B12 from an egg, you should eat the whole thing. The yolk contains the vast majority of the vitamin, so eating only the white will mean you miss out on almost all of it.

The egg yolk is rich in several other nutrients, including vitamins A, D, E, and K, as well as iron, phosphorus, and choline.

The yolk is concentrated with most of the egg's vitamins, minerals, antioxidants (like lutein and zeaxanthin), and healthy fats, which is why it provides so many health benefits in a small package.

Yes, vitamin B12 is also found in other animal-derived foods like meat, dairy, and fish. It is also found in fortified foods, such as certain cereals.

Yes, egg whites are still a healthy food choice, providing a high-quality source of lean protein with very few calories or fat. They are particularly popular for people looking to increase their protein intake without extra fat.