Vitamin B12 is found almost exclusively in animal foods, with shellfish, organ meats, fish, beef, dairy, and eggs providing the richest natural sources. Most adults need 2.4 mcg per day, and a single 3-ounce serving of clams or beef liver can deliver many times that amount. If you eat little or no animal products, fortified foods and a few unusual plant sources can help fill the gap.
Shellfish: The Highest Natural Source
Clams contain more B12 per serving than any other common food. Mixed-species clams provide roughly 49 mcg per 100 grams of raw edible portion, which is more than 20 times the daily requirement for adults. Pacific oysters come in at about 16 mcg per 100 grams, and blue mussels at around 12 mcg. Even a small appetizer-sized portion of any of these shellfish will easily cover your daily needs for weeks in a single sitting.
Meat, Liver, and Poultry
Organ meats are the standout in this category. A quarter cup of liverwurst spread contains 7.4 mcg of B12, and a single ounce of pork liver sausage has 5.7 mcg. If liver isn’t your thing, regular cuts of beef still deliver solid amounts. A 3-ounce serving of top sirloin roast provides about 3.7 mcg, while braised short ribs and broiled top blade steak each offer roughly 3.2 to 3.5 mcg per serving. Any standard portion of beef will more than cover the 2.4 mcg daily target.
Fish: Salmon and Trout Lead the Way
Among fish, trout and salmon are the most reliable B12 sources. A cooked trout fillet (mixed species) provides about 4.6 mcg, and farmed rainbow trout comes in at roughly 2.9 mcg per fillet. Canned pink salmon delivers around 4.2 mcg per 3-ounce serving, while wild coho salmon offers about 3.8 mcg. These are practical, widely available options that make it easy to hit your daily target from a single meal.
Dairy and Eggs
Dairy products provide moderate but meaningful amounts of B12, especially for people who don’t eat much meat. One cup of milk contains 1.3 mcg, which is just over half the daily recommendation. Six ounces of plain yogurt adds another 1.0 mcg. Between a glass of milk at breakfast and yogurt as a snack, you can get close to your full daily requirement without any meat at all.
Eggs also contribute B12, though in smaller amounts than meat or fish. For lacto-ovo vegetarians, combining eggs with dairy products across the day is a practical strategy to maintain adequate intake.
Fortified Foods for Plant-Based Diets
If you follow a vegan or mostly plant-based diet, fortified foods are your most dependable B12 source. Nutritional yeast is the powerhouse here, with some brands providing between 8.3 and 24 mcg per serving, which can be several times the daily requirement in just a couple of tablespoons sprinkled on pasta or popcorn. Check labels, though, because not all brands are fortified equally.
Fortified breakfast cereals typically contain around 0.6 mcg per serving, covering about 25% of your daily needs. Fortified plant-based milks (soy, oat, almond) also contain added B12, though the exact amount varies by brand. If you rely on these sources, eating a mix of fortified foods throughout the day is more reliable than depending on one product alone.
Nori Seaweed: A Surprising Plant Source
Nori is one of the few plant foods that naturally contains B12, rather than getting it through fortification. The B12 content varies by brand and harvest season, ranging from about 23 to 53 mcg per 100 grams of dried nori. In practical terms, eating around 5 grams of nori per day (a few sheets) provides roughly 1.9 mcg of B12, which was enough to significantly improve blood levels of B12 in a four-week trial. All major nori brands tested contained at least 50% of the daily recommendation per packet, making it a viable supplemental source for vegetarians. It’s worth noting, however, that researchers still consider nori less predictable than animal or fortified sources.
How Much You Need
Adults of all ages need 2.4 mcg of B12 per day. During pregnancy, that rises slightly to 2.6 mcg, and during breastfeeding, to 2.8 mcg. Children need less: 0.9 mcg for toddlers ages 1 to 3, 1.2 mcg for kids ages 4 to 8, and 1.8 mcg for ages 9 to 13. There is no established upper limit for B12, because excess amounts are excreted in urine rather than stored to toxic levels.
How Your Body Absorbs B12
Eating B12-rich food is only half the equation. Your stomach lining produces a protein called intrinsic factor, which binds to B12 in your stomach and escorts it to the small intestine for absorption into the bloodstream. Without enough intrinsic factor, or without enough stomach acid to release B12 from food in the first place, you can eat plenty of B12 and still become deficient. This is why deficiency is common in older adults (who naturally produce less stomach acid) and in people with certain autoimmune or digestive conditions.
Cooking Reduces B12 Content
B12 breaks down with heat, so some is lost during cooking. Standard cooking methods (boiling, frying, baking) reduce B12 content by roughly 27 to 33%. Microwave heating tends to be slightly worse, with losses of about 30 to 40%. This doesn’t mean you need to eat everything raw. The B12 content of most animal foods is high enough that even after cooking losses, a standard serving still provides more than the daily requirement. But if your intake is borderline, choosing shorter, gentler cooking times can help preserve more of the vitamin.