The best sources of vitamin B12 are animal-based foods, with clams and beef liver topping the list by a wide margin. A single 3-ounce serving of cooked clams delivers 84.1 mcg of B12, while the same amount of beef liver provides 70.7 mcg. Most adults need just 2.4 mcg per day, so even modest portions of meat, fish, dairy, or eggs can cover your needs.
How Much B12 You Need
Adults 19 and older need 2.4 mcg of vitamin B12 daily. Pregnant women need slightly more at 2.6 mcg, and breastfeeding women need 2.8 mcg. Children’s needs scale with age, starting at 0.4 mcg for infants and reaching adult levels by age 14. These are small amounts compared to what many foods contain, which is why B12 deficiency in people who eat animal products is relatively uncommon.
Your body absorbs B12 through a specific process: stomach acid frees B12 from the protein in food, then a protein called intrinsic factor (made by cells in your stomach lining) binds to the vitamin and carries it to the small intestine for absorption. This two-step process means that anything affecting your stomach acid or intrinsic factor production can reduce how much B12 you actually get from food, regardless of how much you eat.
Meat and Organ Meats
Organ meats are the single richest category of B12 foods. A 3-ounce serving of cooked beef liver contains 70.7 mcg, nearly 30 times the daily requirement. Even if organ meats aren’t your thing, regular muscle meats still deliver meaningful amounts. A 3-ounce lean beef steak provides about 6.9 mcg, close to three times the daily target. Chicken and pork contain B12 as well, though in smaller quantities than beef.
Fish and Shellfish
Shellfish are B12 powerhouses. Cooked clams contain 84.1 mcg per 3-ounce serving, making them the single highest food source available. Among fish, sardines stand out: a can of Atlantic sardines (about 3.7 ounces, drained) packs roughly 9.5 mcg. Sockeye salmon delivers 4.35 mcg per 3-ounce serving, while canned pink salmon with bones provides 3.71 mcg for the same portion.
Tuna is a convenient option too, though it offers less B12 than salmon. A 3-ounce portion of light tuna canned in water contains about 2.24 mcg, which still covers the full daily recommendation in one serving. Canned fish in general tends to be an affordable, shelf-stable way to get B12 into your diet regularly.
Dairy Products
Dairy foods provide moderate B12, and because many people eat them daily, they can add up. A cup of milk (any fat level) contains roughly 0.9 to 1.1 mcg. A 6-ounce container of plain low-fat yogurt provides about 0.95 mcg. Neither hits the full daily target alone, but combined with other foods throughout the day, they contribute meaningfully.
Cheese varies quite a bit by type. Swiss cheese leads the pack at about 4 mcg per cup (diced), while mozzarella, feta, and provolone each offer around 2 to 2.5 mcg per cup. Softer cheeses like cottage cheese deliver less, closer to 0.5 to 0.7 mcg per 4-ounce serving. If you’re relying on dairy as a primary B12 source, harder aged cheeses give you the most per serving.
Eggs
One large egg contains about 0.45 mcg of B12, roughly 19% of the daily target. That means two eggs at breakfast get you about 38% of the way there. Eggs aren’t a complete B12 solution on their own, but they’re a reliable daily contributor, especially paired with other sources like milk or cheese in the same meal.
Fortified Foods for Plant-Based Diets
B12 is naturally found almost exclusively in animal products. If you eat a vegan or largely plant-based diet, fortified foods and supplements are essential, not optional. The most common fortified options include plant milks (soy, almond, oat), breakfast cereals, and nutritional yeast.
Nutritional yeast is popular in vegan cooking, but its B12 content deserves some caution. Unfortified nutritional yeast contains no B12 at all. Fortified versions do, but the amounts vary widely between brands. Independent lab testing by Consumer Lab found that the nutrient levels listed on labels weren’t always accurate. If you’re counting on nutritional yeast as your primary B12 source, it’s worth checking that the brand you buy is fortified and considering a supplement as backup.
Fortified breakfast cereals can be a practical daily source since many provide 100% of the daily value per serving. Check the nutrition label, as fortification levels differ between products and brands.
B12 Supplements
The two most common supplement forms are cyanocobalamin and methylcobalamin. Cyanocobalamin is synthetic and cheaper. Methylcobalamin is the form that occurs naturally in food. In practice, absorption rates are similar: one study found the body absorbed about 49% of a cyanocobalamin dose versus 44% of methylcobalamin, while another found that the body retained methylcobalamin better (excreting about three times less in urine). The differences are small enough that either form works for most people, and factors like age and genetics likely matter more than which type you choose.
Supplements become especially important for people over 50, since stomach acid production tends to decline with age, making it harder to free B12 from food. The B12 in supplements and fortified foods is already in its free form, bypassing the need for stomach acid entirely.
Who’s at Risk for Low B12
Beyond vegans and older adults, certain medications can quietly drain your B12 levels over time. Metformin, widely prescribed for type 2 diabetes, causes B12 deficiency in up to 1 in 10 people who take it. The risk increases with higher doses and longer use. The mechanism appears to involve changes in gut motility, bacterial overgrowth, and reduced absorption in the small intestine.
Proton pump inhibitors, commonly taken for acid reflux, also impair B12 absorption by suppressing the stomach acid needed to release B12 from food. If you take either of these medications long-term, periodic B12 monitoring is worthwhile, and a supplement can offset the absorption gap.
People with conditions affecting the stomach or small intestine, including celiac disease, Crohn’s disease, or a history of gastric surgery, may also absorb B12 poorly regardless of how much they eat. In these cases, high-dose oral supplements or injections can bypass the normal absorption pathway.