Foods high in vitamin B12, ranked by micrograms

The RDA is 2.4 mcg/day, and clams, beef liver, and oily fish are the densest sources. The mcg-per-serving ranking, why B12 is almost absent from plant foods, and when vegetarians and vegans need a supplement.

1. 01

   Clams: ~99 mcg per 100 g

   Clams are the single densest source by a wide margin, carrying ~99 mcg of B12 per 100 g, roughly 40 times the daily target in one serving (USDA FoodData Central). Other shellfish such as mussels and oysters are also rich. They arrive with iron, selenium, and protein. Because the dose is so high, clams are an occasional powerhouse rather than a daily food, and eating them a few times a month meaningfully raises average intake.

2. 02

   Beef liver and organ meats: ~70-83 mcg per 100 g

   Cooked beef liver supplies ~70-83 mcg per 100 g, dozens of times the daily target, and lamb and chicken liver are similar (USDA). Liver is also the densest common source of vitamin A and a strong iron source. A modest 50-100 g serving once a week covers B12 for days. The catch is its very high vitamin A content, which is why liver is best eaten occasionally rather than daily, especially in pregnancy.

3. 03

   Oily fish: mackerel, herring, salmon, ~3-19 mcg per 100 g

   Mackerel leads oily fish at ~19 mcg per 100 g, with herring ~8.5 mcg, sardines ~9 mcg, and salmon ~3-5 mcg (USDA). One serving covers several days of the target while also delivering the EPA and DHA omega-3s that anchor a separate nutrition goal, so a twice-weekly oily-fish habit quietly covers B12 and omega-3s at once. Trout and tuna add useful amounts too.

4. 04

   Beef, lamb, and red meat: ~2-5 mcg per 100 g

   A 100 g cooked serving of beef or lamb supplies ~2-5 mcg, roughly one to two days' worth, alongside highly absorbable heme iron, zinc, and complete protein (USDA). Red meat is the most practical everyday B12 source for meat eaters: a modest daily or near-daily serving effectively guarantees adequate intake, which is why deficiency is rare among people who eat it regularly.

5. 05

   Eggs: ~0.6 mcg each

   One large egg supplies ~0.6 mcg of B12, most of it in the yolk (USDA). Eggs are a modest but convenient and well-absorbed source, and two or three across a day add up to a meaningful share of the target. For lacto-ovo vegetarians who eat no fish or meat, eggs and dairy become the main dietary B12, though many still fall short and benefit from fortified foods.

6. 06

   Dairy: milk, yogurt, and cheese, ~0.5-1.5 mcg per serving

   A cup of milk supplies ~1.2 mcg, a serving of yogurt ~1 mcg, and hard cheeses such as Swiss ~0.9-1.6 mcg per ounce (USDA). Dairy B12 is well absorbed and, taken across the day, is a reliable background source. For vegetarians who eat dairy but not eggs, meat, or fish, milk and cheese are the main dietary supply, though hitting 2.4 mcg from dairy alone takes deliberate stacking.

7. 07

   Fortified foods and supplements: for vegans and older adults

   Unfortified plant foods contain essentially no active B12, so fortified plant milks, nutritional yeast, and some breakfast cereals, plus a supplement, are the route for vegans and strict vegetarians (NIH). The B12 in algae and seaweed is largely an inactive analogue and does not count. Adults over 50 are also advised to lean on fortified foods or supplements, because age-related loss of stomach acid reduces how well B12 is freed from food.