Vitamin B12: Benefits, foods, deficiency, and supplements 

Vitamin B12 

Vitamin B12 is a type of vitamin soluble in water and can be found naturally in certain foods and added to others. It is also available as a dietary supplement or a prescription medication. The compounds with vitamin B12 activity are referred to as cobalamin due to the presence of the mineral cobalt.  

Additionally, it acts as a cofactor for two enzymes, methionine synthase and L-methylmalonyl-CoA mutase. Vitamin B12 is initially bound to protein in food and needs to be released before the body can absorb it. The process begins in the mouth, where food mixes with saliva. The liberated vitamin B12 then attaches itself to haptocorrin, a protein that binds to cobalamin found in saliva. Further release of vitamin B12 from its food matrix occurs in the stomach, thanks to the action of hydrochloric acid and gastric protease. 

In the stomach, it also binds to haptocorrin. In the duodenum, digestive enzymes separate the vitamin B12 from haptocorrin, and this freed vitamin B12 combines with intrinsic factors. Intrinsic factor is a binding protein that is secreted by the stomach’s parietal cells and is responsible for the transport and delivery of vitamin B12.  

The resulting complex is then absorbed in the distal ileum through receptor-mediated endocytosis. However, if vitamin B12 is already present in its free form, such as in fortified foods or dietary supplements, it does not require the separation step.

Vitamin B12 helps your body perform various functions, such as making red blood cells, boosting memory and mood, helping your body produce energy and DNA, and improving your heart health. 

Health benefits of Vitamin B12 

Vitamin B12 offers numerous health advantages. It is recognised for its positive effects on memory, mood, the nervous system, iron levels, heart health, hair, nails, and skin. 

Supports healthy hair, nails and skin 

Adequate levels of vitamin B12 are essential for promoting healthy hair, skin, and nails due to its role in cell production. Insufficient vitamin levels can lead to various dermatologic symptoms, such as hyperpigmentation, nail discolouration, hair changes, vitiligo, and angular stomatitis. However, it remains uncertain whether 
taking a supplement has no effect on skin, nail strength, or hair health in individuals who are well-nourished and not deficient in vitamin B12. 

Blood health 

Vitamin B12 significantly influences the body’s production of healthy red blood cells. Inadequate levels of this vitamin or its deficiency can lead to improper development of red blood cells. Consequently, the red blood cells become more prominent and irregular in shape, which hinders their movement from the bone marrow to the bloodstream. This condition is known as megaloblastic anaemia. Over time, anaemia can cause weakness, fatigue, and other health issues as the body lacks sufficient red blood cells to supply oxygen to the organs. 

Reducing the risk of macular degeneration 

Macular degeneration, a condition primarily impacting central vision, is a disease associated with ageing. Researchers have suggested that maintaining adequate levels of vitamin B12 can help reduce the risk of developing age-related macular degeneration. 

Potentially reduce the risk of breast cancer 

 While there is no conclusive evidence supporting the notion that vitamin B12 alone decreases the likelihood of developing breast cancer, research conducted on various populations has indicated that women who consume higher levels of folate in their diet have a reduced risk of breast cancer. Vitamin B12 collaborates with folate within the body, potentially contributing to mitigating breast cancer risk. Additionally, a preliminary study has suggested that postmenopausal women who consume the least amount of B12 in their diet may face an elevated risk of breast cancer. 

Heart health 

Research indicates that the presence of vitamin B12 in the body has been proven to lower the levels of homocysteine in the bloodstream effectively. Homocysteine, an amino acid, has been closely associated with an elevated risk of heart disease. Recent studies have revealed that individuals with slightly elevated homocysteine levels are more susceptible to experiencing heart attacks and strokes.

Brain health 

According to scientific research, vitamin B12 benefits brain and nervous system function, memory, mood, and depression. Additionally, studies have indicated that individuals with depression tend to have low levels of both folate and vitamin B12. 
 
Furthermore, vitamin B12 deficiency has been linked to impaired memory. Research currently does not indicate that vitamin B12 supplements have the same effect on mood and depression in individuals with normal B12 levels. However, they may be beneficial for those with a vitamin B12 deficiency. 

Food sources of Vitamin B12  

The diet should consist of a diverse range of vegetables, fruits, and grains, with at least half being whole grains. It is recommended to consume fat-free and low-fat milk, yoghurt, cheese, and oils. These dairy products are beneficial as they may provide some amount of B12. Additionally, many ready-to-eat breakfast cereals are fortified with vitamin B12. 
 
To ensure a balanced diet, include a variety of protein foods such as lean meats, poultry, eggs, seafood, beans, peas, lentils, nuts, seeds, and soy products. Fish and red meat are rich sources of vitamin B12, while poultry and eggs contain this essential vitamin. Limiting the consumption of foods and beverages high in saturated, added sugars, and sodium is vital. Rich sources of vitamin B12 include beef, oysters, and certain fish such as salmon and tuna, which surpass the levels found in dairy and poultry. 
 
While plant-based sources are limited, dried, edible seaweed like nori contains notable amounts of vitamin B12, with approximately 77.6 micrograms per 100 grams. Additionally, certain non-animal products like fortified breakfast cereals can provide vitamin B12 at 0.6 micrograms per serving. Furthermore, it is advisable to restrict the intake of alcoholic beverages. Lastly, it is essential to maintain a diet that aligns with your daily calorie requirements.  
 

Food	Amount	Micrograms per serving	Percent DV
Pan-fried Beef liver	3 ounces	70.7 micrograms	2,944%
Nutritional yeast	¼ cup	8.3 to 24 micrograms	346% to 1,000%
Chicken breast	1 cup (140 grams)	0.476 micrograms	19.83%
Canned tuna	3 ounces	2.6 micrograms	108%
Salmon, Atlantic,	3 ounces	2.6 micrograms	108%
Cooked clams	3 ounces	17 micrograms	708%
Egg	1 egg (50 grams)	0.51 micrograms	21.25
Trout	3.5 ounce	7.5 micrograms	312%

 Vitamin B12 supplements  

Supplements and fortified foods contain vitamin B12 in its unbound state, making it easier for the body to absorb. There is a wide range of vitamin B12 supplements available in the market. 

Some claim that specific forms, such as sublingual tablets or liquids placed under the tongue for absorption through the mouth tissues, have better absorption rates than traditional tablets. Still, studies have not found any significant differences. 

Vitamin B12 tablets are also available in high doses that exceed the recommended dietary allowance. Still, it’s important to note that the amount absorbed may not match the high dosage, as an adequate amount of intrinsic factor is required for absorption. In cases of severe vitamin B12 deficiency caused by insufficient inherent factors (pernicious anaemia), doctors may prescribe B12 injections administered into the muscle. 

Vitamin B12 levels 

The vitamin B12 level test is conducted to determine the quantity of vitamin B12 present in the body. The usual range of vitamin B12 levels is typically between 200 to 900 picograms per millilitre, but the measurement method may vary depending on the laboratory’s protocol. 

If a person’s vitamin B12 levels are not within the normal range, they may require treatment. Elevated levels of B12 may indicate liver disease, diabetes, or certain types of leukaemia. 

Conversely, low levels of the vitamin may indicate a B12 deficiency or pernicious anaemia. Doctors commonly utilise a blood test to assess the level of vitamin B12 in a person’s body, although home urine tests are also an option. As part of a routine blood test, doctors can include the examination of vitamin B12 levels. 

While fasting is not obligatory before a B12 test, it may be required if the doctor also intends to analyse other elements in the blood. 

Individuals should inform their doctor about any medications and supplements they are currently taking, as certain substances can impact the accuracy of the test results.

High levels of vitamin B12

An excessively high vitamin B12 level is considered anything above 900 pg/mL. This outcome could indicate liver or kidney issues, diabetes, or specific types of leukaemia. 

Low vitamin B12

Vitamin B12 levels are considered inadequate if they fall below 200 pg/mL. This outcome suggests a deficiency in vitamin B12, pernicious anaemia, or an overactive thyroid. 

Individuals with low levels of vitamin B12 often experience neurological symptoms. It is important to note that the ranges for these results may vary between different laboratories. Therefore, discussing the results and their implications with a doctor is essential. 

The doctor may also assess methylmalonic acid (MMA) levels and other substances to evaluate for vitamin B12 deficiency. 

Vitamin B12 Deficiency 

Insufficient levels of vitamin B12 can result in fatigue, muscle weakness, loss of sensation, and a tingling sensation in the fingers and toes. When the body lacks an adequate supply of vitamin B12, it is unable to generate a sufficient number of healthy red blood cells, which can lead to anaemia. 

Older individuals with insufficient hydrochloric acid production in their stomachs may be prone to vitamin B12 deficiency. This is particularly true for those who have digestive disorders like Crohn’s disease or celiac disease or those who have undergone weight loss or gastrointestinal surgery, as their ability to absorb B12 is reduced. 

Additionally, individuals who follow a vegetarian or vegan diet and do not consume many animal products should consult their healthcare provider to assess their vitamin B12 levels.

Risks and interactions 

Individuals with kidney problems may risk experiencing side effects from B-vitamin supplementation, as these vitamins are excreted through the kidneys. It is important to note that a severe allergic reaction to vitamin B12 supplementation is infrequent but can occur, requiring immediate medical attention. Additionally, potential side effects of taking B-vitamin supplements may include nausea or diarrhoea. Considering the role of these micronutrients in energy production, consuming them in the morning is recommended to avoid any potential impact on sleep if taken too late in the day. 

When evaluating the causes of a deficiency or deficiency symptoms, it is essential to consider an individual’s holistic well-being. This entails considering environmental factors and emotional well-being, as they can significantly affect the body’s capacity to metabolise this essential nutrient. 

According to research, vitamin B12 can have an impact on certain medications. The National Institute of Health has identified several drugs that can hinder the body’s absorption of vitamin B12. 

These include Chloromycetin, which is an antibiotic used to treat infections; proton pump inhibitors like Prilosec and Prevacid that are used to treat acid reflux and peptic ulcer disease; histamine H2-receptor antagonists such as Tagamet and Zantac, and Pepcid that are used to treat peptic ulcer disease, and Metformin, which is used to treat insulin resistance and diabetes. 

You must inform your healthcare provider about any medications, vitamins, or supplements you are taking before consuming vitamin B12. 

Summary

Vitamin B12 is important for various bodily functions, including maintaining a healthy nervous system and producing red blood cells. It is crucial to regularly monitor vitamin B12 levels, especially for individuals who follow plant-based diets, older adults, and those with specific medical or gastrointestinal conditions. Ensuring an adequate intake of vitamin B12 is vital for overall health and well-being. 

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