How Much Is Too Much Vitamin B12?

Vitamin B12 is an essential nutrient with an irreplaceable role in the functioning of our cells. However, excess buildup of this vitamin could be a sign that not all is well in your body.

Buildup of vitamin B12 in the bloodstream may occur as a result of certain illnesses. In rare cases, it can also come about from indiscriminate overuse of vitamins. Though the human body can easily dispose of vitamin B12 easily, this excess could still produce unwanted effects on your health. Are you looking to take B12 vitamins safely? This guide will explain how.

Key Ideas

  • Certain conditions may make your body more prone to accumulating vitamin B12. These include kidney problems, liver problems, and some forms of cancer.
  • High vitamin B12 can lead unwanted symptoms and side effects affecting your skin, kidneys, and digestive bacteria.
  • Taking vitamin B12 supplements rarely causes excess buildup for healthy people. However, supplements should be used with caution if you have health problems, and should only be taken if needed.

High Vitamin B12: What You Need to Know

As we mentioned before, excess vitamin B12 is a sign that something in your body isn’t working as intended. Plus, accumulation can cause symptoms worth keeping a close eye on. To learn more, keep reading!

Certain conditions may make your body more prone to accumulating vitamin B12. These include kidney problems, liver problems, and some forms of cancer. (Source: Lightfieldstudios: 110626402/ 123rf.com)

What Can Cause High Vitamin B12 Levels?

Vitamin B12 is water-soluble, which means after your body has taken as much as it needs, it can dispose of the rest in your urine. For this reason, excess vitamin B12 buildup is rarely caused by simply consuming too much of it (1, 2). However, there are certain conditions which may trigger excess vitamin B12 in your body. Taking supplements may then worsen the severity. These conditions are the most relevant (3, 4):

  • Kidney problems
  • Cancer in blood-forming tissues (leukaemia) (5)
  • Liver problems
  • Polycythaemia vera (a disease which causes an excess of red blood cells) (6)
  • Overconsumption of vitamin B12 (especially when taken as injections)

If you have these conditions and would like to take vitamin B12 supplements, it’s important to first check with your doctor. In some cases, your body may not be able to process supplements correctly, causing the vitamin to build up.

How Much Vitamin B12 Is Too Much?

For a healthy adult, recommended daily intake of vitamin B12 is 2.4 micrograms per day (7). If you have a balanced diet and you aren’t vegan or vegetarian, you ought to easily attain this amount without needing supplements.

However, if you don’t get enough vitamin B12 or your body requires more than average, your doctor may recommend supplements. But how much is too much?

It’s estimated that, for healthy adults, safe vitamin B12 doses in supplements range from 2 milligrams a day to up to 1,000 times the standard daily intake! Injections, on the other hand, should provide no more than 1 milligram (8). Regardless, never go over the recommended dosage unless instructed to by your doctor.

If you experience pain, inflammation, redness, or pus at the site of an injection, tell your doctor immediately. (Source: Keenan: 99C5lrAyxpQ/ Unsplash.com)

What Are the Symptoms of High Vitamin B12?

Increased vitamin B12 levels in your bloodstream are usually a sign of other health problems. As such, it is not well understood which effects are caused by the excess vitamin B12 itself.

However, a 2020 clinical case report revealed side effects from overuse of vitamin B12 to treat a woman with anaemia in hospital (9). In this case, injections of cyanocobalamin (a type of vitamin B12) were given to the patient. Reported symptoms included:

  • Acne
  • Heart palpitations
  • Anxiety
  • Redness in the face
  • Headaches
  • Insomnia

Other moderate symptoms have been found to relate to taking vitamin B12 in different dosages. These include indigestion, a tingling sensation, fever, joint pain, tongue swelling, and red or itchy skin (10).

Tell your doctor if you experience difficulty breathing, chest pain, muscle weakness, and/or increased thirst and increased need to urinate.

What Complications Can B12 Cause?

On top of the immediate symptoms which may appear after taking vitamin B12, some studies suggest possible long-term effects on other body systems and organs:

If you have a balanced diet, you aren’t vegan or vegetarian, and you don’t have any preexisting illnesses, avoid taking B12 supplements unless your doctor recommends them. (Source: Yewell: UaQCpG0frpI/ Unsplash.com)

Who Should Avoid Vitamin B12 Supplements?

As a general rule, people shouldn’t need vitamin B12 supplements unless they have an imbalanced diet, are vegan or vegetarian, or have certain conditions. If none of these apply to you, don’t take B12 supplements unless your doctor recommends them. On top of that general guideline, some people may be especially affected by taking vitamin B12 (16):

  • People allergic or sensitive to cobalt or cobalamin
  • Some people who have undergone heart surgery
  • People with Leber’s disease (a hereditary illness causing loss of eyesight) (17)
  • People with certain blood-related conditions (polycythaemia vera and some types of leukaemia)
  • People who take chloramphenicol

When and How Should I Take Vitamin B12?

Though vitamin B12 is crucial for our health, we need to determine the best way to take it if we want to maximise its benefits.

How Can I Get Enough B12 in My Diet?

Unless you are vegan or vegetarian, it’s quite easy to get recommended amounts of vitamin B12 through food. These foods have the highest vitamin B12 concentration (18):

FoodMicrograms of B12 Per 100 Grams of FoodGrams in Typical ServingMicrograms of B12 Per Serving
Lamb liver84125105
Chicken liver5612570
Beef liver46,812558
Sardines28,424068
Mussels22,125052
Octopus2015030
Serrano ham19,168015
Oysters16,1550 (unidad)8
Camembert cheese2,6401,04
Eggs (from chickens)2,558 (unidad grande)1,45
Fortified breakfast cereals0,6-1,7400,24-0,68
Reduced-fat milk0,4259 (250 ml)1,03
Fat-free yogurt0,41250,5
Fortified soy milk0,38259 (250 ml)0,98

If you follow a vegan or vegetarian diet, you may not have adequate levels of vitamin B12. Most foods which have concentrated amounts of B12 are animal products.

Do I Need Vitamin B12 Supplements?

Certain lifestyles and health conditions can require vitamin B12 supplements:

  • Strict vegan and vegetarian diets
  • Conditions like lupus
  • Malnutrition
  • Digestive problems which hinder vitamin B12’s absorption (gastric surgery or coeliac disease)
  • Pregnancy or breastfeeding

The body absorbs some forms of vitamin B12 better than others. That’s where products like SUNDT liposomal vitamin B12 come in. It’s a nasal spray which may be your fastest, most long-lasting solution for raising your B12 levels. Because SUNDT’s nasal spray doesn’t pass through the digestive system, it’s extra beneficial for people who have digestive problems or who have undergone bariatric surgery for weight loss.

Some people who have undergone heart surgery may be more severely affected by taking vitamin B12 supplements. (Source: Yarmolovich: 111498487/ 123rf.com)

How Do You Take Vitamin B12?

If you need to raise your vitamin B12 levels, the recommended solution could be a supplement or an injection. These general recommendations apply to both cases:

Supplements

  • Vitamin B12 is absorbed better on an empty stomach, so try to take supplements before eating breakfast.
  • If you use tablets designed to dissolve under the tongue, keep them there and don’t chew them.
  • If you use a vitamin B12 spray, make sure to carefully follow the manufacturer’s instructions and your doctor’s advice.
  • Liquid supplements usually cannot be mixed into water or juice. Make sure you take them according to product instructions.

Injections

  • Injections should be prescribed by a healthcare professional and performed by qualified personnel.
  • If your doctor has authorised you or a loved one to perform injections yourselves, make sure you follow every step of their instructions.
  • To prevent infections, avoid scratching the injection site.
  • If you experience pain, inflammation, redness, or pus at the injection site, tell your doctor immediately.

What Exactly Is Liposomal Vitamin B12?

Because vitamin B12 is water-soluble, the body can easily dispose of it through urine, preventing it from building up. This may be good for those of us who already have enough vitamin B12, but it’s not so great for those who really need it.

Liposomal vitamin B12 is both water-soluble and fat-soluble. Because the liposomal version can also mix with fat, it can linger in the body for longer,  benefiting those of us prone to low B12 levels.

This effect is achieved thanks to the liposomes which surround the vitamins. These microscopic liposomes protect nutrients from external damage and facilitate the body’s absorption. Take a look at SUNDT’s liposomal vitamins to learn even more about their benefits!

Our Conclusions

High vitamin B12 levels pose a serious medical concern because of the illnesses that tend to cause them. In a rare few cases, excess vitamin B12 can instead be the result of taking vitamins indiscriminately – especially in injection form.

Some conditions may make you prone to developing low vitamin B12 levels in your bloodstream, and experts may advise supplements or injections. If you’re in this situation, remember to take vitamins responsibly and always put your health and safety first.

If B12 levels are a concern of yours, this guide is a great way to explain it to your loved ones. Feel free to share this article or leave us a comment with your thoughts. We’ll talk soon!

(Featured image source: Grechaniuk: 121683205/ 123rf.com)

References (18)

1. Personal de MedlinePlus. Vitamina B12: MedlinePlus enciclopedia médica [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
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2. Personal de Mayo Clinic. Leucemia [Internet]. Mayo Clinic. Mayo Foundation for Medical Education and Research; 2018
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3. Andrès E, Serraj K, Zhu J, Vermorken AJ. The pathophysiology of elevated vitamin B12 in clinical practice. QJM. 2013 Jun;106(6):505-15.
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4. Zulfiqar AA, Andres E, Lorenzo Villalba N. Hipervitaminosis B12. Nuestra experiencia y una revisión [Hypervitaminosis B12. Our experience and a review]. Medicina (B Aires). 2019;79(5):391-396.
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5. Personal de MedlinePlus. Policitemia vera: MedlinePlus enciclopedia médica [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
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6. Andrès E, Serraj K, Zhu J, Vermorken AJ. The pathophysiology of elevated vitamin B12 in clinical practice. QJM. 2013 Jun;106(6):505-15.
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7. Office of Dietary Supplements - Vitamin B12 [Internet]. NIH Office of Dietary Supplements. U.S. Department of Health and Human Services; 2020.
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8. Personal de la universidad de Oregon. Vitamin B12 [Internet]. Linus Pauling Institute. 2020.
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9. Morales-Gutierrez J, Díaz-Cortés S, Montoya-Giraldo MA, Zuluaga AF. Toxicity induced by multiple high doses of vitamin B12 during pernicious anemia treatment: a case report. Clin Toxicol (Phila). 2020.
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10. Vitamin B12 Side Effects: Common, Severe, Long Term [Internet]. Drugs.com. 2020.
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11. Sherertz EF. Acneiform eruption due to "megadose" vitamins B6 and B12. Europe PMC. 1991.
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12. P; BIO. Vitamin B12-induced acneiform eruption [Internet]. Cutaneous and ocular toxicology. U.S. National Library of Medicine; 2013.
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13. House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, Dresser GK, Spence JD. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA. 2010.
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14. Degnan PH, Taga ME, Goodman AL. Vitamin B 12 as a Modulator of Gut Microbial Ecology. Cell Metabolism. 2014;20(5):769–78.
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15. Xu Y, Xiang S, Ye K, Zheng Y, Feng X, Zhu X, et al. Cobalamin (Vitamin B12) Induced a Shift in Microbial Composition and Metabolic Activity in an in vitro Colon Simulation. Frontiers in Microbiology. 2018;9.
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16. Personal de WebMD. Vitamin B12: Uses, Side Effects, Interactions, Dosage, and Warning [Internet]. WebMD. WebMD; 2020.
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17. Personal de MedlinePlus. Leber hereditary optic neuropathy: MedlinePlus Genetics [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
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18. Food composition database for nutrient intake: selected vitamins and minerals in selected [Internet]. European Union Open Data Portal
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Official Website
Personal de MedlinePlus. Vitamina B12: MedlinePlus enciclopedia médica [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
Go to source
Official Website
Personal de Mayo Clinic. Leucemia [Internet]. Mayo Clinic. Mayo Foundation for Medical Education and Research; 2018
Go to source
Scientific Article
Andrès E, Serraj K, Zhu J, Vermorken AJ. The pathophysiology of elevated vitamin B12 in clinical practice. QJM. 2013 Jun;106(6):505-15.
Go to source
Scientific Article
Zulfiqar AA, Andres E, Lorenzo Villalba N. Hipervitaminosis B12. Nuestra experiencia y una revisión [Hypervitaminosis B12. Our experience and a review]. Medicina (B Aires). 2019;79(5):391-396.
Go to source
Official Website
Personal de MedlinePlus. Policitemia vera: MedlinePlus enciclopedia médica [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
Go to source
Scientific Article
Andrès E, Serraj K, Zhu J, Vermorken AJ. The pathophysiology of elevated vitamin B12 in clinical practice. QJM. 2013 Jun;106(6):505-15.
Go to source
Official Website
Office of Dietary Supplements - Vitamin B12 [Internet]. NIH Office of Dietary Supplements. U.S. Department of Health and Human Services; 2020.
Go to source
University of Oregon Official Website
Personal de la universidad de Oregon. Vitamin B12 [Internet]. Linus Pauling Institute. 2020.
Go to source
Clinical Case Report
Morales-Gutierrez J, Díaz-Cortés S, Montoya-Giraldo MA, Zuluaga AF. Toxicity induced by multiple high doses of vitamin B12 during pernicious anemia treatment: a case report. Clin Toxicol (Phila). 2020.
Go to source
Official Website
Vitamin B12 Side Effects: Common, Severe, Long Term [Internet]. Drugs.com. 2020.
Go to source
Clinical Case Report
Sherertz EF. Acneiform eruption due to "megadose" vitamins B6 and B12. Europe PMC. 1991.
Go to source
Clinical Case Report
P; BIO. Vitamin B12-induced acneiform eruption [Internet]. Cutaneous and ocular toxicology. U.S. National Library of Medicine; 2013.
Go to source
Human Study
House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, Dresser GK, Spence JD. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA. 2010.
Go to source
Scientific Article
Degnan PH, Taga ME, Goodman AL. Vitamin B 12 as a Modulator of Gut Microbial Ecology. Cell Metabolism. 2014;20(5):769–78.
Go to source
In Vitro Study
Xu Y, Xiang S, Ye K, Zheng Y, Feng X, Zhu X, et al. Cobalamin (Vitamin B12) Induced a Shift in Microbial Composition and Metabolic Activity in an in vitro Colon Simulation. Frontiers in Microbiology. 2018;9.
Go to source
Official Website
Personal de WebMD. Vitamin B12: Uses, Side Effects, Interactions, Dosage, and Warning [Internet]. WebMD. WebMD; 2020.
Go to source
Official Website
Personal de MedlinePlus. Leber hereditary optic neuropathy: MedlinePlus Genetics [Internet]. MedlinePlus. U.S. National Library of Medicine; 2020.
Go to source
Database
Food composition database for nutrient intake: selected vitamins and minerals in selected [Internet]. European Union Open Data Portal
Go to source
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