Vitamin B12 absorption from different foods in healthy people
What it found
In healthy people, the body absorbs vitamin B12 from meat and fish much better than from eggs.
Most blue-green algae supplements contain a form that does not work in humans.
What they found
Studies in people
Absorption limit per meal
The gut system that takes in vitamin B12 gets full at about 1.5-2.0 microg per meal. After that point, the body absorbs much less of what is eaten.
Meat and fish absorption
Healthy people absorbed an average of 42% of vitamin B12 from fish. They absorbed 56%-89% from sheep meat and 61%-66% from chicken meat.
Eggs are poorly absorbed
Less than 9% of the vitamin B12 in eggs was absorbed by healthy people. This is much lower than absorption from other animal foods.
Blue-green algae supplements
Most edible blue-green algae sold as supplements mainly hold a fake version of the vitamin. This fake version does not work in humans, so these products are not suitable for vegans.
Other findings
Seaweed and algae sources
Dried green and purple nori seaweed holds good amounts of vitamin B12. Other edible seaweeds had none or only tiny traces.
What the authors conclude
- They note that fortified breakfast cereals are a very useful source of vitamin B12 for older people and vegans.
- They mention that scientists are working on ways to grow vegetables enriched with this vitamin.
How it was done
The body can only take in a limited amount of vitamin B12 at one time through its normal gut system. Scientists wanted to look at how well people absorb this nutrient from different foods.
They looked at existing research on where vitamin B12 comes from and how well healthy adults absorb it. They compared amounts taken in from meat, fish, eggs, seaweed, algae, and fortified cereals.
What it can’t tell you
- We summarised it from the abstract only.
- These numbers apply to healthy adults with normal digestion. They may not reflect what happens in people with gut problems.
- This work looks at single meals. It cannot show how well the body stores or uses vitamin B12 over many months.
Who paid
- Authors work at
- Tottori University, Japan
The paper
- Title
- Vitamin B12 sources and bioavailability
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Watanabe F (2007). Vitamin B12 sources and bioavailability. Experimental biology and medicine (Maywood, N.J.). doi:10.3181/0703-MR-67PubMed 17959839DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error