What Food Has B12? Unveiling the Top Sources of Vitamin B12

Vitamin B12, a crucial nutrient also known as cobalamin, is vital for numerous bodily functions. Naturally abundant in animal-derived foods, it can also be found in fortified products and supplements. Its primary roles include the formation of red blood cells and DNA synthesis. Furthermore, vitamin B12 is indispensable for the healthy functioning and development of brain and nerve cells.

When we consume foods containing vitamin B12, it is bound to protein. The digestive process begins in the stomach, where hydrochloric acid and enzymes work to release vitamin B12 from these proteins, freeing it into its unbound form. Subsequently, this free vitamin B12 combines with a protein called intrinsic factor. This combination is essential for the absorption of vitamin B12 further down in the small intestine, allowing the body to utilize this critical nutrient.

Supplements and fortified foods offer vitamin B12 in its free form, potentially making it easier for the body to absorb. A wide array of vitamin B12 supplements are available, including various formulations. Despite claims suggesting that certain forms, such as sublingual tablets or liquids designed for absorption under the tongue, offer superior absorption compared to traditional tablets, scientific studies have not consistently demonstrated a significant difference in absorption rates. While vitamin B12 tablets are available in high dosages, often exceeding the recommended dietary allowance, it’s important to note that high intake does not guarantee increased absorption. Adequate intrinsic factor is still necessary for the body to effectively absorb vitamin B12. In cases of severe vitamin B12 deficiency stemming from a lack of intrinsic factor, a condition known as pernicious anemia, medical professionals may prescribe vitamin B12 injections directly into the muscle to bypass the absorption issue.

Recommended Daily Intake of Vitamin B12

RDA (Recommended Dietary Allowance): For both men and women aged 14 years and older, the recommended daily intake of vitamin B12 is 2.4 micrograms (mcg). This requirement increases during pregnancy and lactation, rising to 2.6 mcg and 2.8 mcg daily, respectively. [1]

UL (Tolerable Upper Intake Level): The Tolerable Upper Intake Level (UL) represents the maximum daily dose of a nutrient that is unlikely to cause adverse health effects in the general population. Notably, no upper limit has been officially established for vitamin B12. This is because a toxic level for vitamin B12 has not been identified. However, some research suggests that daily supplements of 25 mcg or higher might be associated with an increased risk of bone fractures. [2]

Vitamin B12’s Role in Health

Cardiovascular Health

Vitamin B12 plays a role in the breakdown of homocysteine, an amino acid. Elevated levels of homocysteine are linked to a heightened risk of cardiovascular disease and stroke. This is because high homocysteine may contribute to the formation of blood clots, promote excess free radical production, and impair the normal function of blood vessels. Insufficient vitamin B12 can lead to increased homocysteine levels in the body.

While studies have shown that vitamin B12 supplementation can effectively lower homocysteine levels, these findings haven’t consistently translated into a reduced risk of cardiovascular events in individuals taking vitamin B12 supplements. Consequently, the American Heart Association does not currently recommend the routine use of B vitamin supplements for the purpose of reducing cardiovascular disease risk. [1] Nevertheless, vitamin B12 supplements can be particularly important for individuals with genetic predispositions that result in elevated homocysteine levels.

Cognitive Function

Elevated homocysteine levels are also associated with an increased occurrence of Alzheimer’s disease, dementia, and general cognitive decline. Similar to the findings related to cardiovascular disease, research indicates that vitamin B12 supplementation can reduce homocysteine blood levels, but this reduction has not consistently resulted in lower rates of cognitive decline. A comprehensive Cochrane review examining folic acid supplements, with or without vitamin B12, and their impact on cognition, found no significant effect of these supplements compared to a placebo on cognitive function in healthy elderly individuals or those with dementia. [3] Another review encompassing 14 randomized controlled trials also found no consistent evidence of cognitive benefits from vitamin B12 supplements, whether taken alone or in combination with other B vitamins, in people with normal or impaired cognitive function. [4] These findings do not rule out potential benefits for specific individuals with low vitamin B12 levels, highlighting the need for further research in this area.

Top Food Sources of Vitamin B12: What Food Has B12?

When considering “What Food Has B12”, it’s important to focus on natural, animal-based sources and fortified options. Here’s a detailed look at the best food sources of vitamin B12:

Fish and Shellfish: These aquatic foods are excellent sources of vitamin B12. Examples include salmon, tuna, sardines, trout, and shellfish like clams, oysters, and mussels. Incorporating a variety of fish and shellfish into your diet can significantly boost your B12 intake.

Variety of seafood including fish and shellfish, natural sources of vitamin B12.

Liver: Organ meats, especially liver, are among the most concentrated sources of vitamin B12. Beef liver, chicken liver, and lamb liver are all rich in this essential vitamin. Liver was historically a dietary staple and remains a potent source of B12.
Red Meat: Beef, lamb, and venison are good sources of vitamin B12. The B12 content varies depending on the cut and preparation, but red meat generally contributes significantly to B12 intake for meat-eaters.
Eggs: Eggs, particularly the yolks, contain vitamin B12. Both chicken eggs and duck eggs are viable sources. Including eggs as part of a balanced diet can contribute to meeting your daily B12 needs.
Poultry: Chicken, turkey, and other poultry are sources of vitamin B12, although generally less concentrated than red meat or organ meats. Poultry is a widely consumed food group and contributes to overall B12 intake.
Dairy Products: Milk, cheese, and yogurt are dairy products that provide vitamin B12. The amount varies across different types of dairy, but these are common and accessible sources for many. Consider incorporating a variety of dairy into your diet if you consume these products. Options include milk, cheddar cheese, swiss cheese, and Greek yogurt.
Fortified Nutritional Yeast: For vegetarians and vegans seeking non-animal sources, fortified nutritional yeast is an excellent option. It’s specifically produced to contain added vitamin B12. Always check the nutrition label to confirm B12 fortification.
Fortified Breakfast Cereals: Many breakfast cereals are fortified with vitamins, including vitamin B12. These can be a convenient way to increase B12 intake, especially for those who eat cereal regularly. Again, checking the nutrition label is crucial to ensure fortification with B12.
Enriched Soy or Rice Milk: Plant-based milk alternatives like soy milk and rice milk are often enriched with vitamin B12 to make them nutritionally comparable to cow’s milk in terms of B12 content. Opt for fortified versions to ensure B12 intake from these sources.

Signs of Vitamin B12 Deficiency and Toxicity

Deficiency

It’s important to note that measuring vitamin B12 levels in the blood alone may not be the most accurate method for diagnosing a deficiency. Some individuals with a deficiency can exhibit normal B12 blood levels. More reliable markers for assessing vitamin B12 activity include blood levels of methylmalonic acid (MMA) and homocysteine. These values tend to increase when a vitamin B12 deficiency is present. Estimates suggest that up to 15% of the general population may experience vitamin B12 deficiency. [1]

Several factors can contribute to vitamin B12 deficiency:

Avoiding Animal Products: Individuals who abstain from meat, fish, poultry, and dairy products are at a higher risk of vitamin B12 deficiency. This is because vitamin B12 is naturally found primarily in animal-based foods. Studies have indicated that vegetarians often have lower vitamin B12 blood levels. [5] Therefore, individuals following vegetarian or vegan diets should prioritize including B12-fortified foods or a B12 supplement in their dietary regimen. This is particularly critical for pregnant women, as adequate vitamin B12 is essential for fetal neurological development, and deficiency can lead to irreversible neurological damage in the fetus.
Lack of Intrinsic Factor: Pernicious anemia is an autoimmune condition characterized by the body’s immune system attacking and potentially destroying cells in the stomach lining. This destruction can lead to a deficiency in intrinsic factor, a protein crucial for vitamin B12 absorption in the small intestine. Without sufficient intrinsic factor, vitamin B12 cannot be properly absorbed, even from high-dose supplements. This deficiency can result in various types of anemia and neurological damage.
Inadequate Stomach Acid or Medications that Reduce Stomach Acid: A more common cause of vitamin B12 deficiency, especially among older adults, is insufficient stomach acid. Stomach acid is necessary to release vitamin B12 from food proteins. It is estimated that 10-30% of adults over the age of 50 experience difficulty absorbing vitamin B12 from food due to reduced stomach acid production. [1] Furthermore, individuals who regularly use medications to suppress stomach acid, such as proton-pump inhibitors, H2 blockers, or antacids, for conditions like gastroesophageal reflux disease (GERD) or peptic ulcer disease, may also face challenges in absorbing vitamin B12 from food. These medications can hinder the release or reduce the production of stomach acid, potentially preventing vitamin B12 from being liberated into its usable form in the stomach. While research hasn’t consistently shown a higher prevalence of deficiency in people using these medications, individuals using them long-term and who have other risk factors for vitamin B12 deficiency should be closely monitored by their healthcare provider. They may also consider using fortified foods or supplements, as these forms of vitamin B12 are typically absorbed effectively and do not require stomach acid for absorption.
Intestinal Surgeries or Digestive Disorders Causing Malabsorption: Surgical procedures affecting the stomach, where intrinsic factor is produced, or the ileum, the final segment of the small intestine where vitamin B12 absorption occurs, can elevate the risk of deficiency. Certain digestive diseases, including Crohn’s disease and celiac disease, which negatively impact the digestive tract, also increase the risk of vitamin B12 deficiency due to malabsorption.
Medications that Interfere with Absorption: Long-term use of metformin, a medication commonly prescribed for type 2 diabetes, is strongly linked to vitamin B12 deficiency and lower folic acid levels. Metformin can interfere with the absorption of these vitamins, potentially leading to increased homocysteine levels and an elevated risk of cardiovascular disease. [6] Proton pump inhibitors and histamine blockers, prescribed to reduce stomach acid, are also associated with reduced vitamin B12 levels.

Signs of vitamin B12 deficiency can manifest in various ways, including:

Megaloblastic anemia: Characterized by abnormally large red blood cells and a reduced overall number of red blood cells. This condition arises due to insufficient vitamin B12 intake or poor absorption.
Pernicious anemia: A specific type of megaloblastic anemia caused by a lack of intrinsic factor, hindering vitamin B12 absorption.
Fatigue and weakness: General feelings of tiredness and reduced physical strength.
Nerve damage: Manifesting as numbness and tingling sensations, particularly in the hands and legs.
Memory loss and confusion: Cognitive impairments affecting memory and mental clarity.
Dementia: A more severe form of cognitive decline.
Depression: Mood disturbances and persistent sadness.
Seizures: Involuntary muscle contractions and loss of consciousness in severe cases.

Toxicity

Vitamin B12 is a water-soluble vitamin, meaning that any excess amount not utilized by the body is excreted through urine. Generally, oral vitamin B12 supplements, even at high doses up to 1000 mcg per day for treating deficiency, are considered safe. The Institute of Medicine states that “no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals.” [1] However, it is always advisable to consult with a healthcare professional before starting any high-dosage supplement regimen.

Did You Know?

B vitamin complex supplements are often promoted for their purported ability to boost energy levels and mood. Individuals with a B vitamin deficiency may experience an increase in energy levels after starting supplementation because vitamin B12 is directly involved in the production of healthy blood cells and can correct anemia if present. However, there is no scientific evidence to support the claim that B vitamin supplements provide benefits for individuals who are not deficient in these vitamins.
Vegan diets often recommend incorporating Brewer’s or nutritional yeast for their B12 content. However, yeast does not naturally contain vitamin B12; it is only present if the yeast has been fortified with it. It is important to be aware that while some brands of nutritional yeast are fortified with B12, not all are.
Nori (purple laver), a dried edible seaweed used in sushi rolls, is sometimes touted as a plant-based source of vitamin B12. While nori does contain small amounts of active vitamin B12, the amount can vary significantly among different types of seaweed, with some containing negligible amounts. Therefore, nori is not considered a reliable food source of vitamin B12.

Vitamins and Minerals

References

Last reviewed March 2023

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