How much B12 is in a glass of whole milk?

December 31, 2025 •

3 min read

According to the U.S. National Institutes of Health, one cup (8 ounces) of 2% milk contains approximately 1.3 micrograms (mcg) of vitamin B12, providing over half of the daily value for an adult. While whole milk's B12 content is comparable, a single glass contributes significantly to your daily requirements.

Quick Summary

A single 8-ounce glass of whole milk contains a significant amount of vitamin B12, which is absorbed more effectively by the body than B12 from other animal products like beef or eggs. The B12 content helps support nerve function, red blood cell formation, and DNA synthesis.

Key Points

Significant B12 per glass: An 8-ounce glass of whole milk typically contains 1.0-1.3 mcg of B12, fulfilling a large portion of an adult's 2.4 mcg daily requirement.
High bioavailability: The B12 found in dairy products is absorbed more efficiently by the body than the B12 from meat, fish, or eggs.
Not a complete solution: Relying solely on milk is generally not enough to prevent a B12 deficiency; a varied diet with other sources is necessary.
B12 varies across dairy: Different dairy products, like cheese or yogurt, and even fortified milk alternatives have varying B12 concentrations.
Age affects absorption: Older adults may have impaired absorption of B12 from food, making fortified foods or supplements a recommended alternative to natural sources.
Not dependent on fat content: The B12 content is comparable in whole and skim milk, as it is a water-soluble vitamin and not stored in the milk fat.

Unpacking the Vitamin B12 Content of Whole Milk

A single 8-ounce glass of whole milk typically contains about 1.0 to 1.3 micrograms (mcg) of vitamin B12. Given that the Recommended Dietary Allowance (RDA) for vitamin B12 in adults is 2.4 mcg per day, one cup of whole milk provides a substantial portion of this requirement. This makes whole milk, and dairy in general, a valuable source of this essential nutrient, particularly for lacto-vegetarians or those looking to supplement their intake.

The B12 in milk is naturally occurring and is a byproduct of bacterial synthesis in the ruminant animal's digestive system. This natural form is not only readily available but also has a higher bioavailability compared to the synthetic B12 found in supplements. Studies have shown that the body absorbs vitamin B12 from milk and dairy products more efficiently than from sources like beef, fish, or eggs, highlighting the unique benefit of dairy as a dietary source.

Factors Influencing B12 Levels

While the B12 content is relatively consistent, certain factors can slightly influence the overall amount. The primary difference often lies between different milk products rather than different batches of whole milk.

Processing: Processes like pasteurization can slightly affect nutrient levels. A preliminary step in laboratory testing, which simulates some processing, involves heating milk to release protein-bound cobalamins. However, commercially, this impact is generally minimal for B12.
Source: Milk from different animal species can have varied B12 concentrations. For example, while cow's milk is a reliable source, goat milk contains significantly less.
Fortification: Some dairy products or milk alternatives, like soy milk, are fortified with B12 to increase their nutritional value. This means fortified products might contain more B12 than their non-fortified counterparts.

How Bioavailability Boosts Dairy's B12 Power

One of the key advantages of getting B12 from dairy is the bioavailability. This refers to the proportion of a nutrient that is absorbed and used by the body. The B12 in milk is bound to a specific protein, which, when consumed, is more efficiently released and absorbed in the intestine. This is particularly relevant for older adults, who may have difficulty absorbing B12 from other sources due to reduced stomach acid production. Research suggests that dairy B12 is up to three times more bioavailable than B12 from meat.

Other Excellent Dietary Sources of B12

Milk and dairy products are not the only sources of B12. A balanced diet should include a variety of these foods to ensure adequate intake, especially for non-vegetarians. Here is a list of other sources of B12:

Beef liver (cooked, 3 oz): 70.7 mcg
Clams (cooked, 3 oz): 17.0 mcg
Salmon (cooked, 3 oz): 2.6 mcg
Beef (ground, 3 oz): 2.4 mcg
Fortified breakfast cereals (1 serving): 0.6 mcg or more
Swiss cheese (1 slice): 0.9 mcg
Eggs (1 large): 0.5 mcg

Comparison Table: B12 in Different Milk Types and Sources


Food Source	Serving Size	Approximate B12 (mcg)	% of Adult Daily Value	Comments
Whole Milk	1 cup (244g)	1.3	~54%	Highly bioavailable and naturally occurring.
Skim Milk	1 cup (244g)	1.3	~54%	Comparable B12 to whole milk; B12 is water-soluble.
Fortified Soy Milk	1 cup (250ml)	1.0	~42%	Fortified, not naturally present. Check label for exact amount.
Beef, ground (lean)	3 oz	2.4	~100%	Significant source, but bioavailability is lower than dairy.
Salmon, Atlantic	3 oz	2.6	~108%	Excellent source, but preparation can affect content.

Is Milk Enough to Prevent a B12 Deficiency?

While a glass of milk is a great step toward your daily B12 needs, it is generally not enough on its own to prevent a deficiency, especially for individuals with restricted diets or absorption issues. A varied diet including multiple B12 sources is ideal. For those who avoid animal products entirely, fortified foods and supplements are crucial. Older adults, in particular, should consider fortified foods or supplements, as absorption from natural food sources may be impaired after age 50.

Conclusion

A single glass of whole milk provides a significant and highly bioavailable amount of vitamin B12, contributing substantially to an adult's daily nutritional needs. While it is an excellent dietary component, it should be part of a broader, balanced approach to ensure sufficient intake. Those with specific dietary restrictions or absorption concerns should consider consulting a healthcare professional to ensure they are meeting their vitamin B12 requirements. The unique bioavailability of B12 from dairy underscores its importance in a healthy diet for many.

Further reading: For comprehensive information on the importance of vitamin B12, visit the National Institutes of Health Fact Sheet.

Frequently Asked Questions

No, whole milk does not necessarily have more vitamin B12 than skim milk. As a water-soluble vitamin, B12 is not removed during the fat-reduction process, so their B12 content is generally comparable.

One 8-ounce glass of whole milk can provide a significant portion, roughly half, of the 2.4 mcg Recommended Dietary Allowance (RDA) for vitamin B12 for adults.

Studies suggest that the bioavailability of B12 from dairy products is higher, potentially up to three times higher, than from meat, fish, or poultry.

While milk is an important source of B12, it is not a complete solution. A varied diet with other B12 sources is recommended to prevent a deficiency, especially for those with dietary restrictions or absorption issues.

Yes, other dairy products like yogurt and cheese are also good sources of B12. For instance, Swiss cheese and plain yogurt provide notable amounts.

Yes, many milk alternatives are fortified with vitamin B12, as they do not naturally contain it. The amount can vary by brand, so it is best to check the product label.

Vitamin B12 is essential for several bodily functions, including red blood cell formation, DNA synthesis, nerve function, and converting food into energy.