16 Benefits Of Vitamin B12, Dosage, And Side Effects

The much underrated group of nutrients that are actually vital to your wellbeing.

Reviewed by Dr. Abby Kramer, DC
Written by Ravi Teja Tadimalla, Professional Certificate In Food, Nutrition & Health
Edited by Arshiya Syeda
Fact-checked by Aparna Mallampalli, BEd (Biological Sciences), MSc (Microbiology), Diploma In Nutrition  • 

Vitamin B12 plays a vital role in many bodily functions. But the benefits of vitamin B12 are less discussed. In central and south America, Mexico, the Indian subcontinent, and some parts of Africa, Vitamin B12 deficiency is a severe issue (1).
This vitamin majorly improves heart health, helps manage skin diseases, improves memory, and helps with mood improvement. The daily dose of vitamin B12 is 2.4 micrograms in adults (2).

From the article below, know what it says about vitamin B12 and the benefits it offers. Also, look at which foods are rich in this vitamin and the symptoms of its deficiency. Scroll down!

What Is Vitamin B12? How Does It Help?

Vitamin B12, also known as cobalamin, helps in the proper functioning of the body’s blood cells and nerves. It also plays a role in DNA synthesis (3).

The vitamin is also known for megaloblastic anemia prevention, a type of anemia that makes people weak. Studies have shown that a deficiency in this nutrient could lead to the condition (4).

Vitamin B12 is absorbed in the body in two steps. In food, this vitamin is attached to a protein. The hydrochloric acid in the stomach separates vitamin B12 from this protein synthesis. The vitamin then combines with another protein made by the stomach (called the intrinsic factor). It is then absorbed in the body (5).

Individuals with pernicious anemia (a decrease in red blood cells) may be deficient in vitamin B12, as their bodies do not have the ability to produce the intrinsic factor (3).

Vitamin B12 is important for performing various bodily functions. In the following section, we will discuss the crucial benefits of vitamin B12 in detail.

What Are The Health Benefits Of Vitamin B12?

1. Helps In The Formation Of Red Blood Cells

Vitamin B12 may increase red blood cell count
Image: Shutterstock

Vitamin B12 (along with folate) helps in the formation of red blood cells. Without enough vitamin B12, red blood cells do not divide normally as they are supposed to and become too large. This makes them difficult to get out of the bone marrow (6).

This can result in fewer red blood cells in the bloodstream to carry oxygen to the body, leading one to feel tired and weak. This condition is also called pernicious anemia, and if not treated, it can damage the brain, heart, and other organs of the body (6).

2. May Prevent Birth Defects

Vitamin B12 is one of the crucial ingredients during pregnancy. A deficiency of this vitamin may cause infertility and recurrent abortions (7).

Starting pregnancy with a vitamin B12 deficiency may increase the risk of neural tube defects in the newborn. It may also lead to preterm delivery. The deficiency in the mother may also cause the same in the newborn if sufficient vitamin B12 is not available in breast milk. However, these implications need more research (7).

Women with vitamin B12 levels lower than 300 ng/L have a higher risk of delivering infants with birth defects (8). Increasing B12 levels beyond this may reduce the risk, though more research is warranted (8).

Vitamin B12 is required to create the new maternal and fetal cells and prevent neural tube defects in the newborn (9). It works together with folate to achieve this. A deficiency of vitamin B12 can also lead to folate deficiency, and this adversely affects pregnancy.

The vitamin may treat nausea and morning sickness, which are often associated with pregnancy. However, research in this aspect is limited.

3. Might Promote Skin Health

Vitamin B12 deficiency has been associated with changes in the skin. The most common symptom is hyperpigmentation (10).

Other dermal complications of this deficiency include vitiligoi  XAn autoimmune disease that causes loss of skin color in patches due to deficiency of melanin and also affects the mouth, hair, and eyes. and other skin lesionsi  XAn abnormal change in the appearance of the skin or tissues that is usually caused due to trauma or disease. (11), (12).

Vitamin B12 can also help treat some serious skin ailments. One study found that a vitamin B12 cream could reduce the extent and severity of eczema. This was especially true in the case of eczema in children (13).

You can get the cream from a pharmacy. Apply it to the affected areas twice a day. Make sure you consult your doctor. B12 also helps with inflammation reduction and its side effects, and this is one reason it can counteract eczema.

Vitamin B12 may also help reduce shingles pain. Anecdotal evidence suggests that taking 1000 mcg of vitamin B12 on a daily basis may help treat the condition. However, as research is limited, we recommend you check with your doctor before using it.

Studies suggest that folic acid and vitamin B12, along with sun exposure, can induce repigmentation (14).

Vitamin B12 may also help fight cellulitei  XA condition where the fat deposition beneath the skin causes lumpy, dimpled flesh on thighs, buttocks, and stomach. , but there are limited studies to prove this.

4. May Improve Hair Health

Vitamin B12 may promote healthy hair growth
Image: Shutterstock

Vitamin B12 helps in the formation of red blood cells. Some believe this may promote hair growth.

Vitamin B12 deficiency was observed in those with hair loss (15). At the base of hair follicles, we have tiny blood vessels that connect to the roots of each hair strand. These blood vessels carry oxygen to the hair, thereby boosting hair growth and preventing hair fall.

5. May Promote Heart Health

Vitamin B12 has shown potential for heart disease prevention and treatment. The nutrient lowered homocysteine (a particular amino acid), the high levels of which could elevate the risk of ischemic heart disease (16).

Deficiencies of B vitamins, in general, were linked to higher homocysteine levels and an increased risk of stroke (16). This may also cut down the long-term costs associated with expensive medical treatments.

Vitamin B12 was also found to reduce blood pressure in preschool children (17).

6. May Aid Diabetes Treatment

Though there is no direct link between vitamin B12 and diabetes treatment, the nutrient may treat diabetic retinopathy (damage of blood vessels in the eye) (18).

It may aid the treatment of diabetic neuropathy (nerve damage in the legs and feet), though further research is warranted (19). Anecdotal evidence suggests that the vitamin may also treat some of the symptoms of neuropathy, including numbness, pain, and a prickling sensation.

Vitamin B12 reduces homocysteine levels in the blood, which can otherwise lead to retinopathy (20).

More interestingly, metformin, a commonly prescribed diabetic drug, may cause vitamin B12 deficiency (21). This is why it might be a good idea to supplement it, especially in the case of diabetes. Pernicious anemia is vitamin B12 deficiency experienced in the case of type 1 diabetes (22).

7. May Help Maintain Bone Health

Low plasma levels of vitamin B12 have been linked to lower bone mineral density in humans. Studies suggest that the vitamin may affect bone formation. It has also been linked to osteoblastic activity (bone formation) (23).

High homocysteine levels and low vitamin B12 levels have also been associated with osteoporosisi  XA bone disease that causes bones to become weak and brittle due to low bone mineral density and decreased bone mass. (24). Since vitamin B12 helps lower homocysteine levels, it may play a beneficial role here.

In a study conducted on older women, lower levels of vitamin B12 were linked to increased hip bone loss (25).

8. May Help Prevent Macular Degeneration

Vitamin B12 may prevent macular degeneration
Image: Shutterstock

Age-related macular degeneration has been associated with reduced plasma vitamin B12 levels and increased homocysteine levels. Intake of B12 supplementation may prevent the condition (26). However, more thorough studies are needed to understand the mechanism.

Another study also states that high levels of homocysteine may increase the risk of age-related macular degeneration (27). Since vitamin B12 helps lower the levels of this amino acid, it could be helpful in the treatment of AMD.

In another study in women, daily supplementation with folic acid, vitamin B12, and vitamin B6 over a seven-year period was found to reduce the risk of age-related macular degeneration (28).

9. May Boost Brain Health

Studies show that supplementing with vitamin B12 along with antidepressants may improve depressive symptoms. B12 deficiency may be associated with depression (29).

Adequate vitamin B12 levels may also increase the probability of recovery from depression. However, we need more studies to confirm this finding (30).

The vitamin may also have a beneficial effect on mood. It is believed the vitamin produces brain chemicals responsible for better mood stabilization, though we need more research to understand the mechanism. Anecdotal evidence suggests that it may help treat stress and certain anxiety disorders.

Vitamin B12, when combined with omega-3 fatty acids, could also slow down memory decline in adults. The nutrients improve cognitive function and also slow down the progression of mild cognitive impairment (31).

Another study states that the vitamin can prevent brain volume loss in the elderly. Individuals taking adequate vitamin B12 had a reduced risk of brain shrinkage/atrophy (32).

Vitamin B12 deficiency may also lead to dementia and Alzheimer’si  XA progressive neurodegenerative disease that causes impaired memory and mental functioning due to the shrinkage of brain cells. , although more studies are needed to understand the mechanism (33), (34).

As vitamin B12 also aids cell production (a process called methylation), it may help improve the symptoms of autismi  XA serious developmental disorder that affects the overall cognitive, emotional, and social ability of an individual to interact. (35).

10. May Help With Energy Production

Vitamin B12 plays a role in cellular energy production (36). However, there is no research stating that it may boost energy levels or improve athletic performance, as popularly believed.

Some research states that vitamin B12 deficiency could lead to increased levels of fatigue (37).

11. May Improve Sleep

There is limited research in this aspect. However, one study states that adequate vitamin B12 levels may improve sleep-wake rhythm disorders (38). This study has been conducted only on two patients, so we need more large-scale studies to understand the impact this vitamin can have on sleep quality.

It is believed that a deficiency of B12 may cause insomnia. However, more research is needed to establish the link.

12. May Help In The Treatment Of Fibromyalgia

Vitamin B12 may help manage Fibromyalgia
Image: Shutterstock

It is believed that low levels of vitamin B12 may lead to fibromyalgiai  XA disorder characterized by widespread musculoskeletal pain and tenderness, accompanied by fatigue, altered sleep, and mood issues. and chronic fatigue syndrome. There is a lack of research in this aspect.

One study states that vitamin B12 injections may work as analgesics, thereby aiding the treatment of fibromyalgia (39).

Other research also links fibromyalgia to higher levels of homocysteine in the blood (40). As vitamin B12 lowers homocysteine levels, it may potentially aid in the treatment of fibromyalgia.

13. May Help Improve Symptoms Of Tinnitus

Tinnitus is a condition characterized by a buzzing sensation in the ears. One study states that vitamin B12 may improve the symptoms of tinnitus (41).

The deficiency of vitamin B12 has been linked to chronic tinnitus and noise-induced hearing loss.

Insufficient Evidence For The Following

14. May Stabilize Digestive Health

Vitamin B12 is believed to help with the production of digestive enzymes, which promote digestive health and ensure the proper breakdown of food. The nutrient could foster the gut environment by promoting the growth of healthy gut bacteria.

It is also believed to eliminate the harmful bacteria in the gut, possibly preventing other digestive system health issues like inflammatory bowel disease.

15. May Help With Weight Loss

Though we need more research, some reports state that vitamin B12 helps the body convert fat into energy and also aids the breakdown of carbs.

The vitamin may boost your metabolism, and some believe this may help with weight loss.

However, please consult your doctor before using B12 for this purpose.

16. May Prevent Mosquito Bites

Vitamin B12 may prevent mosquito bites
Image: Shutterstock

Though we don’t know if it can ease mosquito bites, some believe vitamin B12 may repel mosquitoes. It is thought to exude a mosquito repellent-like smell. However, we suggest you talk to a specialist before using it for this purpose.

What Are The Food Sources Of Vitamin B12?

The following are some of the best food sources of vitamin B12 (42):

  • Beef and chicken liver (3 ounces contain 3,375% RDA of the vitamin)
  • Salmon (A 108-gram filet contains 821% RDA)
  • Tuna (3 ounces contain 385% of the RDA)
  • Organic yogurt (1 container of 170 grams contains 53% of the RDA)
  • Raw milk (1 cup contains 41% of the RDA)
  • Lamb (3 ounces contains 34% of the RDA)
  • Low-fat yogurt (8 ounces contains 18% of the RDA)
  • Egg (1 large whole egg contains 10% of the RDA)
  • Roasted chicken breast (3 ounces contains 5% of the RDA)

protip_icon Trivia
People who consume a vegan diet are often advised to include Brewer’s yeast in their diet to meet their daily recommended allowance of vitamin B12.

Including these foods in your diet can help you meet your regular vitamin B12 requirements. But what if you don’t? How do you know you are deficient in this vitamin?

What Are The Symptoms Of Vitamin B12 Deficiency?

The following are some of the most common symptoms of the deficiency:

  • Muscle aches
  • Weakness/chronic fatigue
  • Poor memory
  • Dizziness
  • Anxiety and mood swings/depression
  • Heart palpitations
  • Nausea and abdominal cramping
  • A poor appetite

Taking adequate vitamin B12 can help you avoid these symptoms. Find out the recommended dosage in the next section.

What Is The Recommended Vitamin B12 Dosage?

The following table can help you with the details (2):

Age Group
0 to 6 months
8 ounces
7 to 12 months
0.5 mcg
1 to 3 years
0.9 mcg
4 to 8 years
1.2 mcg
9 to 13 years
1.8 mcg
14 years and older
2.4 mcg
Adult and adolescent pregnant females
2.6 mcg
Adult and adolescent lactating females
2.8 mcg

What About Vitamin B12 Shots? Who Needs Them?

These are the synthetic versions of the vitamin. You can take vitamin B12 from foods or acquire the vitamin from a man-made version of the nutrient known as cyanocobalamin.

Vitamin B12 shots are nothing but injections containing very high amounts of cyanocobalamin. These shots can quickly boost the vitamin B12 levels in the individual.

Who needs them? You need these shots only if you are severely deficient (or are at risk) in vitamin B12. Vitamin B12 injections are available only by prescription, which means a clinical diagnosis is a must. You can’t (and shouldn’t) administer the shots on your own without the advice of a doctor or dietitian (43).

The following factors can increase the risk of vitamin B12 deficiency:

  • Smoking
  • Alcohol abuse
  • Sticking to a vegetarian or vegan diet
  • Aging
  • Thyroid disorder
  • People on certain diabetes medications
  • Gastrointestinal disorders like Crohn’s diseasei  XA chronic inflammatory bowel disease that causes the digestive tract to become swollen and irritated, causing pain and diarrhea.
  • Surgical removal of parts of the stomach

One major benefit of vitamin B12 shots is that they bypass the stomach and are directly absorbed into the bloodstream. Hence, in case you have gastrointestinal issues or had stomach surgeries, these shots could be a better option over oral supplements.

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Dried purple laver (Nori), an edible seaweed used to make sushi rolls, is the most suitable source of vitamin B12 for vegans.

Side Effects Of Excess Vitamin B12

Vitamin B12 is water-soluble. This means that excess of it can pass out of your system through urine. Vitamin B12 has not shown to cause any harm. However, certain medications can interfere with your body’s ability to absorb vitamin B12. The most common of these include antiepileptici  XA class of drugs that help control abnormal brain activity and decrease the episodes of seizures. drugs (44).

Vitamin B12 can also interfere with metformin, the anti-diabetes drug (21). It can also interfere with Proton Pump Inhibitors, drugs used to treat acid reflux and peptic ulcers (45).

Infographic: Causes Of Vitamin B12 Deficiency

Vitamin B12 (cobalamin) is an essential nutrient for proper body functioning. This vitamin has many benefits, from helping to form red blood cells to improving sleep quality. However, deficiency of vitamin B12 may lead to several adverse effects. Apart from dietary deficiency, vitamin B12 deficiency may occur due to many underlying medical health issues. Check out the infographic below to learn about the causes of vitamin B12 deficiency.

causes of vitamin b12 deficiency (infographic)

Illustration: StyleCraze Design Team

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The benefits of vitamin B12 are numerous. It can improve your overall health if included as a part of your daily diet. Vitamin B12 can help form red blood cells, prevent congenital disabilities, and promote skin, hair, cardiovascular, bone, brain, and digestive health. Other benefits of B12 include weight loss and improved sleep. It may also aid in treating fibromyalgia and diabetes. Foods like beef, chicken liver, salmon, tuna, raw milk, lamb, egg, and organic yogurt are the best sources of vitamin B12. Try including these foods regularly in your diet to minimize the risk of vitamin B12 deficiency. Vitamin B12 in the form of methylcobalamin and adenosylcobalamin may offer benefits for nervous system function. However, a proper dosage of vitamin B12 is important to avoid potential side effects.

Frequently Asked Questions

Is vitamin B12 water-soluble?

Yes, B12, just like other B vitamins, is water-soluble. This simply means that having an overdose of vitamin B12 is highly unlikely as it dissolves in water, and the remaining amount is passed out through urine.

What is the best time to take a vitamin B12 supplement?

In the mornings, after breakfast, or during lunch. You may also take vitamin B12 during the night. But since they promote energy generation, taking it in the day could be ideal (information on this is mixed, though).

Vitamin B12 supplements may work between 48 to 72 hours, especially if they are taken by someone who is deficient in the vitamin.

Is too much vitamin B12 bad for you?

Not really. As we discussed, B12 is a water-soluble vitamin. Maintain your dosage as per the recommended levels or as directed by your healthcare provider.

Is vitamin B12 good for treating erectile dysfunction?

There is no research on this. If you are going to use the vitamin for treating ED, make sure to consult your doctor.

Can vitamin B12 cause pimples?

There is no evidence here. If you experience pimples, it could mean some underlying condition. Consult a dermatologist.

How long should I take B12 supplements?

Vitamin B12 supplements may take anywhere between six months to a year to address your deficiency. However, always consult with your doctor first before you choose to take or extend the dose of your B12 supplements.

Key Takeaways

  • Poor memory, muscle ache, weakness, and anxiety may be a few symptoms of Vitamin B12 deficiency.
  • Your heart health and memory may improve if you include vitamin B12 in your routine.
  • It may promote skin and hair health.
  • Foods such as eggs, salmon, and tuna are rich in this vitamin.
  • Vitamin B12 may interfere with certain medications.

Worried about a potential B12 deficiency? Check out this informative video that uncovers the 7 warning signs to keep an eye on and helps you take proactive steps towards better health.


Articles on StyleCraze are backed by verified information from peer-reviewed and academic research papers, reputed organizations, research institutions, and medical associations to ensure accuracy and relevance. Check out our editorial policy for further details.
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