Vitamin B12 is an essential vitamin, meaning it must be obtained from nutrition. It is naturally present in animal products, such as meats, fish, eggs and dairy. Consuming vitamin B12-rich foods contribute to a healthy nervous system and circulatory system.
A vitamin B12 deficiency can lead to severe symptoms if left untreated. Deficiency of vitamin B12 increases the risk of various diseases such as anaemia and neurological conditions. The elderly are sensitive to vitamin B12 deficiency and have a higher risk of developing these conditions. Vegetarians and vegans have to ensure that they receive enough vitamin B12 from fortified foods or supplements since B12 is not naturally found in non-animal food sources.
More details about how vitamin B12 is used by the body can be read in our previous articles.
Part 1: Vitamin B12 in the Body
Part 2: Vitamin B12 Deficiency
Daily Requirement
Vitamin B12 is an essential nutrient for everyone. The German Nutrition Society recommends that adults consume 4 µg of vitamin B12 daily. People who are pregnant or breastfeeding have a higher requirement and need 4.5 and 5.5 µg of vitamin B12, respectively. However, not all of the B12 you consume will be completely absorbed. Instead, approximately half of the total vitamin B12 from a meal will reach the bloodstream. Avoid getting your daily B12 from a single large portion in one meal. Your body can absorb more B12 if you eat smaller portions of B12-rich foods across multiple meals. Avoid getting your daily B12 from a single large portion in one meal.
Vitamin B12-Rich Foods
These vitamin B12-rich foods are nutritious examples of foods that you can include in your diet to help meet your daily requirements.
Meat
Liver (beef or lamb)
Contains 65 µg vitamin B12 / 100g
Beef and lamb liver are very-rich sources of vitamin B12 and iron. You won’t need to eat very much to meet your daily requirement of vitamin B12.
Rabbit
Contains 10 µg vitamin B12 / 100g
Rabbit is a lean cut of meat that is high in vitamin B12. A small serving
Beef (various cuts)
Contains 5 µg vitamin B12 / 100g
Beef is an excellent source of vitamin B12. 100 g is sufficient to cover the daily requirement.
Seafood
Oysters
Contains 14,6 µg vitamin B12 / 100g
Oysters are notorious for their micronutrient content. They are incredibly rich in vitamin B12 and zinc.
Mackerel
Contains 9 µg vitamin B12 / 100g
A mackerel fillet is a great source of vitamin B12, vitamin D and heart-healthy unsaturated fats.
Herring
Contains 8,5 µg vitamin B12 / 100g
A few herring fillets will provide you with enough vitamin B12, as well as monounsaturated fats.
Mussels
Contains 6,2 µg vitamin B12 / 100g
Mussels will provide you with a lot of vitamin B12 and iron.
Trout
Contains 5 µg vitamin B12 / 100g
A single serving of trout contains the daily requirement of vitamin B12 and is a great source of vitamin D and unsaturated fats.
Cheese
Swiss cheese
Contains 3,1 µg vitamin B12 / 100g
Swiss cheese contains high levels of vitamin B12. Two slices can cover half of the daily requirement.
Tilsit cheese
Contains 2,2 µg vitamin B12 / 100g
Tilsit cheese contains large amounts of vitamin B12. Tilsit cheese can help to meet the daily requirements of vitamin B12, especially for those on a vegetarian diet.
Edam cheese
Contains 2,1 µg vitamin B12 / 100g
Edam is a very good source of vitamin B12, especially in a vegetarian diet. 100 g cover 2/3 of the daily requirement.
Fortified foods
It is possible to find B12-fortified foods in some supermarkets, depending on local availability. Fortified foods are foods with added vitamins and minerals to help meet the daily nutrient requirements of consumers. Foods that are sometimes fortified with B12 include cereals, juices and dairy. The vitamin content of fortified foods should be listed on the nutritional information panel. This information includes how much of the daily requirement a single serving supplies.
Unlike animal sources, the B12 content in fortified foods is easier to digest. This means people who have difficulty with digestion may absorb more B12 from fortified foods than from animal products. Fortified foods are also an alternative for vegans and vegetarians and can help avoid a decrease in B12 levels.
Plant Sources of Vitamin B12
Animals don’t produce vitamin B12 themselves, but soil and aquatic bacteria produce the vitamin which accumulates higher up in the food chain, especially in ruminant animals. It follows that bacteria may also contribute to the vitamin B12 content in non-animal food sources, theoretically providing an alternative for vegans and vegetarians, or simply contributing to your daily fruit and vegetable intake. However, plants and vegetables, fermented foods like sauerkraut and tempeh, and selected types of mushrooms contain only trace amounts, making them inadequate sources of B12.
Alternative non-animal sources like cyanobacteria (such as spirulina) and algae (such as dried purple nori) have substantial vitamin B12 content. These foodstuffs have a higher vitamin B12 content than the plant examples mentioned above, but also contain analogues of vitamin B12 that are biologically inactive. The pseudovitamin B12, as these analogues are called, do not provide nutritional value and can interact with the transport of vitamin B12 through the body. While foodstuffs like spirulina or nori do contain some of the true vitamin B12, the pseudovitamin reduces the overall efficacy and may not improve vitamin B12 status. Cyanobacteria, algae and other plant sources are not recommended as a suitable source of vitamin B12.
Supplements Guide
Vitamin B12 is essential for everyone, and the recommended daily intake of vitamin B12 is 4 µg. Supplements are an alternative source of vitamin B12 for anyone on a restrictive diet that eats little or no animal foods, such as vegan and vegetarian. B12 supplements typically contain the vitamin listed in the ingredients as cyanocobalamin or methylcobalamin; either form is equally as effective for increasing circulating B12 levels. A tablet that contains between 1 µg and 1000 µg (1 mg) can be taken safely. Vitamin B12 supplements may be better tolerated if taken in the morning.
- Ingredients: cyanocobalamin or methylcobalamin
- Dose: between 1 µg and 1000 µg (1 mg) daily
- Instructions: Take in the morning, with or without food
People who have trouble absorbing B12, as discussed previously, may choose intramuscular injections from a healthcare provider. This method bypasses the intestinal absorption of B12 and supplies the vitamin directly to the bloodstream.
What happens if I take too much?
It is not possible to take in too much vitamin B12 from food, due to the way that this vitamin is absorbed. Furthermore, there is no reported upper limit for vitamin B12. The upper limit for nutrients is the maximum daily intake from all sources (foods and supplements) that should not pose health risks. This means that vitamin B12 intake and supplementation typically does not cause severe adverse effects. However, some people have experienced mild discomforts with high doses of B12 supplements, so you may need to adjust your dose and speak with your doctor.
You should also discuss B12 supplementation with your doctor if you regularly take medications. It is possible for B12 supplements to interact with some medications such as statins, contraceptive pills and others.
References
Vitamin B12 Fact Sheet for Health Professionals
Nutritional aspects of depression. Cell Physiol Biochem. 2015;37(3):1029-43.
Folate, vitamin B12, and neuropsychiatric disorders. Nutr Rev. 1996 Dec;54(12):382-90.
Vitamin B12 (Cobalamine). Deutsche Gesellschaft für Ernährung e.V.
Nutritional information for vitamin B12-rich foods from BLS database.
