This article explores the subject of vitamin B12 benefits, but you can only get the benefits if you ensure that you include foods rich in the vitamin in your diet. You need to obtain B12 from the foods you eat because your body can’t make it.
If you are a vegan not taking supplements or fortified foods, you are likely not getting enough B12 because the vitamin is mostly found in foods derived from animals, such as meat, organ meats, fish, and poultry.
Vitamin B12 ( also known as cobalamin) is one of the water-soluble B-complex vitamins essential for health and wellness. However, people on a strict vegan diet don’t get enough because plant foods don’t have it. Studies show that the incidence of cobalamin deficiency is high among vegans who do not take supplements or eat fortified foods.
Many vegans don’t get enough B12 benefits
Pawlak et al. reported a high incidence of deficiency among vegetarians, especially vegans who do not take supplements. They recommended screening all people on strict vegan diets for deficiency.
Vitamin B12 deficiency is common in countries where a large proportion of the population is vegetarian due to cultural factors. Woo et al. recommended monitoring the cobalamin status of vegetarian communities in countries such as India and rural communities in northern China who rarely take fortified foods or supplements.
While certain bacteria in the human colon can produce cobalamin, it is not available for absorption, according to Degnan et al. Only ruminants, such as cattle, sheep, and goats, and animals that eat their poop (coprophagy or cecotrophy), such as rabbit and guinea pig, can use B12 produced in their colon.
Ruminant animals can absorb cobalamin produced by microbes resident in the rumen section of their first stomach compartment.
Vegans need B12 supplementation
You likely don’t enjoy eating your poop, and you certainly don’t have rumen stomach compartments like cattle. So, if you don’t want to eat meat, organ meats, and fish, you may increase your naturally-sourced B12 by adding milk and eggs to your diet (lacto-ovo-vegetarian diet). However, the bioavailability of vitamin B12 from eggs is much lower than in meat, poultry, and fish.
According to Watanabe, the bioavailability of cobalamin from “fish meat, sheep meat, and chicken meat averaged 42%, 56%-89%, and 61%-66% respectively,” while the vitamin in eggs was poorly absorbed (<9% bioavailable). However, milk is an excellent source of bioavailable cobalamin.
The best way to get B12 vitamin benefits is through eating more foods naturally rich in the nutrient. It is better to get your vitamins from natural sources because they may also offer other health-boosting benefits, such as blood-forming iron, bodybuilding proteins, and healthy bowel function promoting dietary fiber.
People on a strict vegan diet that excludes eggs and milk have fewer natural food options, such as fermented plant sources, seaweed (dried purple laver, also known as nori), and algae. Many vegans rely on fortified foods and supplements to get the vitamin.
This article offers an in-depth exploration of the health benefits of vitamin B12 and why you need to pay closer attention to your intake of the vitamin, especially if you are vegan.
Vitamin B12 benefits: 17 health-boosting functions of cobalamin
Here are 17 B12 vitamin benefits that show why you need more of it in your diet.
1. B12 promotes the health of the nervous system
An adequate intake of vitamin B12 is essential for the healthy functioning of the central nervous system (CNS), including the brain and spinal cord.
B12 is essential to health because the biologically active (bioactive) forms of the vitamin function as coenzymes in the metabolic and synthetic processes that ensure healthy functioning of the brain, the spinal cord (CNS), and the peripheral nervous system (PNS).
Cobalamin is involved in the maintenance of the CNS through regulation of DNA synthesis, synthesis of myelin, and metabolism of amino and fatty acids.
Myelin sheaths protect nerve axons and help them transmit electrical signals faster and more efficiently. Myelin production is, therefore, essential for maintaining the health of the central nervous system (CNS).
The bioactive forms of vitamin B12 involved in supporting the health of the CNS include methylcobalamin (MeCbl) and adenosylcobalamin, also known as coenzyme B12 (AdoCbl).
MeCbl and AdoCbl are involved as coenzymes (or cofactors) in key processes that maintain CNS health.
A coenzyme (or cofactor) is an organic substance whose presence is needed before an enzyme-catalyzed reaction can take place. Methylcobalamin, for instance, acts as a cofactor of methionine synthase in the synthesis of the essential amino acid methionine.
2. Vitamin B12 may promote brain health and cognitive function
Vitamin B12 supports brain health and cognitive function. Deficiency of the vitamin may be associated with cognitive impairment.
Moore et al. reported that epidemiological evidence suggests a link between vitamin B12 deficiency and cognitive decline and that supplementation may help to improve cognition in individuals with deficiency.
The researchers concluded that low cobalamin is associated with neurodegenerative disease and cognitive impairment. They also reported that B12 levels “in the subclinical low-normal range” were associated with Alzheimer’s disease, vascular dementia, and Parkinson’s disease. They added that vegetarianism and metformin use may lower cobalamin levels and increase the risk of cognitive impairment.
While some cases of dementia are reversible with vitamin B12 therapy, it does not improve cognition in people without preexisting deficiency of the vitamin, according to the researchers.
Supplementation may also help to maintain cognitive function in those who are at risk of deficiency. However, the intervention must start before the onset of neuronal damage.
The role of cobalamin in maintaining brain health and cognitive function is not entirely surprising due to its role in the healthy functioning of the nervous system of which the brain is a part.
Smith et al. reported that homocysteine-lowering B vitamins (B12, B6, and folate) slowed down brain atrophy in older adults with mild cognitive impairment (MCI).
Another study found that B vitamins (B12, B6, and folate) may slow down cognitive decline in people with elevated homocysteine and mild cognitive impairment.
3. B12 may boost metabolism in deficient individuals
Vitamin B12 plays a role in the metabolism of amino and fatty acids.
Adenosylcobalamin (or coenzyme B12) is the co-factor of methylmalonyl-CoA mutase in the conversion of methylmalonyl-CoA to succinyl-CoA. Succinyl-CoA plays a role in the energy-generating citric acid cycle (Kreb’s cycle) and the metabolism of fatty and amino acids.
A study found that B12 deficiency increased fatigue levels and depression in lacunar stroke patients.
Another study reported that deficiency of the vitamin can result in hematologic symptoms, such as low energy, low exercise tolerance, fatigue, and shortness of breath. The researchers noted that supplementation reduced the symptoms.
Thus, individuals susceptible to cobalamin deficiency may experience B12 vitamin benefits through supplementation. Such benefits may include a boost in energy levels and improvement in deficiency symptoms, such as weakness, tiredness, fatigue, and lethargy.
4. Vitamin B12 supports red blood cell formation
Your body needs vitamin B12 for the formation of healthy blood cells. The vitamin plays a role — alongside iron and folate (folic acid or vitamin B9) — in hematopoiesis.
Hematopoiesis (or hemopoiesis) involves the formation of the cellular components of blood, including the maturation of red blood cells in the bone marrow.
The bioactive form of B12, adenosylcobalamin (coenzyme B12), plays a role in the formation of succinyl-CoA required for the production of the iron-containing heme component of hemoglobin and myoglobin.
5. Cobalamin prevents pernicious anemia
Vitamin B12 is referred to as the “anti-pernicious anemia factor” due to its role in preventing the condition.
Pernicious anemia (also known as vitamin B12 deficiency anemia) is a form of megaloblastic anemia. Folate deficiency anemia is another form of megaloblastic anemia.
Pernicious anemia is characterized by impaired DNA synthesis, decreased production of red blood cells, increased production of defective and immature blood cells that are larger than normal. Defective red blood cells result in impaired delivery of oxygen to vital body tissues and organs.
6. B12 supplementation may help prevent depression
Some studies suggest that B12 supplementation may help prevent depression.
A study reported that data suggests a relationship between vitamin B12 and depression and that timely supplementation can delay the onset of depression and boost the effectiveness of antidepressants.
Another study found that supplementation can boost the ability of antidepressants to relieve the symptoms of depression.
There is a link between depression and low vitamin B12 in physically disabled older women, Penninx et al. reported. They found that deficiency was associated with a twofold risk of severe depression.
Another study concluded that high cobalamin levels were associated with an improved probability of recovery from major depression.
B12 is a cofactor in the synthesis of mood-altering neurotransmitters, including serotonin and dopamine, according to Valizadeh et al.
Cobalamin deficiency may alter emotions, mood, sleep patterns, and deficiency can lead to neuropsychiatric problems. The researchers also reported a case of obsessive-compulsive disorder (OCD) linked with B12 deficiency.
7. Cobalamin reduces the risk of age-related macular degeneration, optic neuropathy
Research findings suggest that people with low B12 levels are at a higher risk of developing age-related macular degeneration (AMD) and that supplementation may help prevent it.
Deficiency of the vitamin may also be associated with optic neuropathy and progressive decline in visual acuity.
According to Huang et al., age-related macular degeneration was associated with elevated homocysteine levels and decreased vitamin B12 levels.
Another study found that daily supplements of B12, folic acid (vitamin B9), and vitamin B6, may reduce the risk of developing AMD in women at high risk of cardiovascular disease.
8. B12 lowers the risk of miscarriage, preterm birth, and low birth weight
There is an increased risk of low birth weight and birth defects — such as neural tube defects — in babies born to mothers who suffered B12 deficiency during pregnancy, studies reported.
Rogne et al. found that low maternal cobalamin levels during pregnancy increased the risk of preterm birth and low birth weight.
Pregnant women deficient in cobalamin also had a higher risk of miscarriage.
According to Molloy et al., B12 deficiency may be associated with infertility and repeated spontaneous abortion. The authors also concluded that deficiency may be associated with an increased risk of birth defects, such as neural tube defects (NTD), and preterm births.
Mothers with inadequate vitamin stores during pregnancy also gave birth to babies suffering deficiency-related health issues.
9. Cobalamin may support memory performance
Researchers have linked Vitamin B12 deficiency with various cognitive issues, including memory loss.
Deficiency of the vitamin is associated with impaired memory, impaired cognition, neural symptoms such as tingling and numbness, according to Jatoi et al.
The researchers reported that the cognitive effects of deficiency were likely due to decreased myelination. They concluded that supplementation may improve the symptoms of memory loss in cobalamin deficient individuals.
Soh et al. also reported that cognition, including memory, recall, and recognition, may be affected by cobalamin levels.
Low vitamin levels “within the normal range” may be “associated with poorer memory performance,” according to Kobe et al. The authors said that memory impairment may be due to “reduced microstructural integrity of the hippocampus.”
The role of cobalamin in healthy memory function is likely linked with its role in preventing brain atrophy and dementia in older people with mild cognitive impairment (MCI).
10. Low B12 may increase the risk of heart disease
Multiple studies reported a link between high homocysteine blood levels, higher levels of total cholesterol, high LDL cholesterol and triglyceride levels, and consequently a higher risk of cardiovascular diseases.
The observation led to the suggestion that homocysteine-lowering vitamin B12 used in conjunction with B6 and folate may lower the risk of heart disease.
A study reported that high homocysteine levels were associated with an increased risk of stroke. The researchers concluded that supplementation with B12, folate, and B6, may lower the risk of stroke — including subarachnoid hemorrhage and ischemic stroke — by reducing homocysteine levels.
Another team of researchers concluded that B12 deficiency may counter the cardio-protective benefits of vegetarian diets. People on vegan diets have a reported higher risk of cobalamin deficiency and thus a higher risk of elevated homocysteine levels (hyperhomocysteinemia).
The authors advised people on a vegan diet to use supplements.
However, Zhao and Schooling did not find a link between high homocysteine levels and increased risk of coronary artery disease/myocardial infarction (CAD/MI). They also found no evidence that high vitamin B12, folate, and B6 reduced the risk of CAD/MI. But they acknowledged that low levels of the vitamin may be associated with an unfavorable lipid profile.
11. Vitamin B12 may promote bone health and prevent osteoporosis
Vitamin B12 may promote healthy bones and help stave off osteoporosis in women, some studies suggest.
B12 status may be linked with bone health in older women, according to Dhonukshe-Rutten et al. The authors reported that bone mineral density was associated with B12 levels in women, but they found no association in men.
They also found that the incidence of osteoporosis was higher among women with “marginal” and “deficient” levels of B12 than in women with normal levels of the vitamin.
Tucker et al. reported that deficiency may be a factor in osteoporosis. According to the authors, men and women with low plasma levels had lower average bone mineral densities (BMD).
12. Cobalamin improves the condition of skin, hair, and nails
According to Almohanna et al., B12, folate, vitamin D, iron, and selenium may play a role in premature graying/whitening, and supplementation may improve the symptoms.
B12 deficiency may have adverse dermatological effects, such as hyperpigmentation, oral effects such as glossitis, and changes in hair and nail condition, another study found.
Cobalamin excess and deficiency may have other dermatological effects, such as atopic dermatitis, aphthous stomatitis, vitiligo, and acne.
Noppakun and Swasdikul reported a case of premature greying, generalized skin and nails hyperpigmentation due to vitamin B12 deficiency anemia (pernicious anemia).
They reported that treatment with intramuscular injection of cyanocobalamin reversed the symptoms.
Studies have also reported effects, such as reversible facial hyperpigmentation, due to cobalamin deficiency.
However, some researchers have expressed concern about the risks of prescribing vitamin and mineral supplements to treat skin, hair, and nail conditions.
Burns et al. suggested that doctors should help to raise awareness about the risks of widespread use of so-called “beauty supplements” marketed as “natural” supplements to improve skin condition. The authors reported that some of the products were toxic, teratogenic, and increased the risk of diabetes.
Brescoll et al. also reported that people with cobalt sensitivity may show adverse cutaneous (skin) reactions to cobalamine replacement therapy. The reactions may include acne, rosacea, and allergic site reactions, such as anaphylaxis, the authors reported.
13. B12 deficiency and cancer risk
Low levels of cobalamin may increase the risk of certain cancers, and supplementation may reduce the risk of such cancers, some studies found.
One study found that low B12 increased the risk of gastric cancer. However, other studies suggested that high B12 increased the risk of cancer.
Fanidi and associaties reported that high vitamin levels may increase lung cancer risk. Hung et al. also concluded that a high intake of cobalamin was associated with an increased risk of developing lung cancer.
The results suggested that excessive intake of cobalamin may be harmful and that experts should warn people about the risks of supplementation.
Another study concluded that folic acid and B12 supplementation may increase the risk of colorectal cancer. The team of medical researchers said their study suggested the need to limit supplementation to patients with deficiency.
However, Peterson et al. urged more work to clarify the role of the B vitamins in inflammation and cancer.
14. Vitamin B12 and sleep disorder
Vitamin B12 may play a role in the treatment of insomnia and excessive daytime sleepiness (EDS), researchers reported.
A study found that supplementation with vitamin B12, B6, melatonin, extrafolate, and magnesium improved insomnia regardless of the cause. However, the exact role or contribution of B12 to the alleviation of insomnia was not clear from the study.
Another study found that females with higher vitamin B12 levels reported improved sleep quality and a lower need for sleep medication.
The researchers recommended more studies with larger sample sizes for a better understanding of the relationship between B12 levels and sleep. Improvement in sleep quality may bring many health benefits, including boosting immunity and resistance to infectious diseases such as pneumonia.
Khawaja et al. (2019) reported a case of excessive daytime sleepiness (EDS) caused by vitamin B12 deficiency. However, the researchers reported there was no evidence of circadian rhythm disorder in the patient and that the mechanism through which cobalamin deficiency caused EDS was not clear.
15. Hydroxycobalamin is an effective antidote for cyanide poisoning
Hydroxocobalamin, a form of cobalamin, was found effective and approved by FDA for treating cyanide poisoning.
The approval came after multiple research studies found that hydroxocobalamin was an effective antidote for poisoning with cyanide salts that can cause death.
Meillier and Heller reported that hydroxocobalamin prevented death from cyanide poisoning and had less severe side effects than sodium thiosulfate.
The FDA first approved intravenous hydroxocobalamin for cyanide poisoning in 2006.
Hydroxocobalamin counters cyanide toxicity by binding with cyanide to form cyanocobalamin (vitamin B12) excreted through urine.
16. Vitamin B12 and treatment of canker sores
Vitamin B12 is effective in treating aphthous stomatitis (RAS), also known as canker sores.
A study found that people with recurrent aphthous stomatitis (canker sores) were more likely to have lower levels of B12 and folate. The researchers concluded that cobalamin deficiency played a role in causing canker sores and that supplementation may reduce the recurrence and severity of the condition.
Another study concluded that cobalamin appeared effective for treating canker sores regardless of the vitamin status of the patient.
However, Lalla et al. reported that daily multivitamin supplementation did not prevent or reduce the number and duration of canker sore episodes. They recommended that doctors should not routinely prescribe multivitamin supplementation to prevent canker sores.
17. Cobalamin and nerve pain due to shingles
B12 may be effective in treating post-herpetic neuralgia (PHN), a type of neuropathic pain caused by shingles.
A study found that cobalamin relieved the symptoms of post-herpetic neuralgia (PHN) and may help in cases of painful peripheral neuropathy. Experts believe that B12 may alleviate neuropathic pain through multiple mechanisms, including promoting myelination, nerve regeneration, and decreasing ectopic nerve firing.
According to Wang et al., cobalamin could play a complementary role in treating PHN.
Local injection of methylcobalamin (a bioactive form of vitamin B12) with lidocaine administered within 4–7 days of onset may relieve acute PHN, Xu et al. reported.
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