Placing a B12 tablet under your tongue produces results similar to muscular injections with fewer complications.

Image Credit: OksanaKiian/iStock/GettyImages Vitamin B12, cobalamin, plays an important role in human health and disease, and a deficiency in B12 can result in physical and mental health problems. Most people get the amount they need through supplements, but animal products like eggs and milk — and even some plants — also serve as good sources. Side effects from this water-soluble vitamin are rare, but it’s been known to trigger the sometimes-fatal allergic reaction known as anaphylaxis, so speak with your doctor about it.

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 Tip Even high doses of vitamin B12 are considered safe, and side effects are rare. There have, however, been cases of people experiencing the allergic reaction known as anaphylaxis after taking B12, underscoring the importance of talking to your doctor before including B12 in your health regimen.

Read more: Pros & Cons of Vitamin Supplements

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Cobalamin Has Low Bioavailability

Some dietary cobalamin fails to reach your bloodstream. In fact, your ability to process cobalamin decreases as you increase your intake, so a large meal offers only slightly more cobalamin than a smaller meal. In addition, older adults often lose their ability to process cobalamin. All of this contributes to the likelihood of developing cobalamin deficiency.

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 Dietitians typically recommend getting 2.4 micrograms of cobalamin per day. However, some governments have increased this value to 8.6 micrograms. A person's gender, age and other factors affect these recommendations, and all values assume normal cobalamin processing.

Sublingual Cobalamin Offers Many Benefits

You can get cobalamin supplements in muscular and oral doses. The authors of a June 2016 report in the New Zealand Medical Journal noted the increasing popularity and many advantages of sublingual administration. Placing a B12 tablet under your tongue produces results similar to muscular injections with fewer complications.

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 A February 2018 paper in Clinical Nutrition also documented the effectiveness of sublingual administration. In this study, a weekly dose of 2,000 micrograms restored circulating cobalamin levels in patients with mild B12 deficiency. Interesting, daily doses of 50 micrograms had an even better effect.

Read more: What Are Techniques to Increase Vitamin Absorption?

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Cobalamin

Has Few Side Effects Taking larger doses of cobalamin can help you overcome bioavailability issues, but whenever you consider upping your dose of a supplement, it’s normal to have concerns about safety issues. Fortunately, the authors of a 2018 report in Food Fortification in a Globalized World concluded that even large doses of B12 remain safe, so 2,500 micrograms shouldn’t pose a health problem.

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 Read more: B12 Injections Side Effects

Cobalamin Causes

Allergic Reactions While dose size doesn’t matter, cobalamin can cause an allergic reaction, as reported in the May 2018 edition of Cureus. An older woman following a vegan diet for five years was prescribed a weekly 1,000-microgram injection of B12 and showed signs of anaphylaxis while receiving the second injection. A 2,000-microgram oral dose was prescribed, addressing the deficiency without side effects. The study noted that very few patients experience cobalamin-related anaphylaxis. Still, you should share any observed side effects with your doctor.

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 Read more: Will an Allergy Cause Throat Swelling?

Cobalamin

Comes From Many Sources Because only microorganisms can make cobalamin, you have to get it from your diet or a supplement. Most animal products contain cobalamin. Farm animals offer you the best source of cobalamin, according to a February 2015 report in Nutrition Reviews. Organ meat has the greatest concentration of this vitamin. Dairy products contain considerably less. Vegetables rarely have cobalamin, but some edible seaweeds have it.

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 Read more: Symptoms of Low B12

Traditional

Cooking Changes Cobalamin Content Food processing can have a dramatic effect on nutrients. For example, traditional cooking methods may cause a 62 percent decrease in cobalamin, according to a 2011 report in the Journal of Nutritional Science and Vitaminology. Modern techniques like vacuum-packed pouch cooking can eliminate this loss. Read more: Boiled Vegetables vs. Steamed

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  references
  
      Nutrients: Foods and Supplements Associated with Vitamin B12 Biomarkers among Vegetarian and Non-Vegetarian Participants of the Adventist Health Study-2 (AHS-2) Calibration Study
    
      Nutrients: Vitamin B12-Containing Plant Food Sources for Vegetarians
    
      National Institutes of Health: Vitamin B12
    
      Cureus: Anaphylactic Reaction to Cyanocobalamin
    
      Nutrition Reviews: Vitamin B12 in Meat and Dairy Products
    
      Journal of Nutritional Science and Vitaminology: Loss of Vitamin B12 in Fish (Round Herring) Meats During Various Cooking Treatments
    
      Nutrients: Vitamin B12 Among Vegetarians
    
      Food Fortification in a Globalized World: Efficacy and Safety of Vitamin B12 Fortification
    
      New Zealand Medical Journal: Sublingual Vitamin B12 Compared to Intramuscular Injection in Patients With Type 2 Diabetes Treated With Metformin
    
      European Journal of Clinical Nutrition: Treatment of Vitamin B12 Deficiency-Methylcobalamine? Cyancobalamine? Hydroxocobalamin?-Clearing the Confusion
    
      Clinical Nutrition: Effect of Two Different Sublingual Dosages of Vitamin B12 on Cobalamin Nutritional Status in Vegans and Vegetarians With a Marginal Deficiency
       




  references
  
      Nutrients: Foods and Supplements Associated with Vitamin B12 Biomarkers among Vegetarian and Non-Vegetarian Participants of the Adventist Health Study-2 (AHS-2) Calibration Study
    
      Nutrients: Vitamin B12-Containing Plant Food Sources for Vegetarians
    
      National Institutes of Health: Vitamin B12
    
      Cureus: Anaphylactic Reaction to Cyanocobalamin
    
      Nutrition Reviews: Vitamin B12 in Meat and Dairy Products
    
      Journal of Nutritional Science and Vitaminology: Loss of Vitamin B12 in Fish (Round Herring) Meats During Various Cooking Treatments
    
      Nutrients: Vitamin B12 Among Vegetarians
    
      Food Fortification in a Globalized World: Efficacy and Safety of Vitamin B12 Fortification
    
      New Zealand Medical Journal: Sublingual Vitamin B12 Compared to Intramuscular Injection in Patients With Type 2 Diabetes Treated With Metformin
    
      European Journal of Clinical Nutrition: Treatment of Vitamin B12 Deficiency-Methylcobalamine? Cyancobalamine? Hydroxocobalamin?-Clearing the Confusion
    
      Clinical Nutrition: Effect of Two Different Sublingual Dosages of Vitamin B12 on Cobalamin Nutritional Status in Vegans and Vegetarians With a Marginal Deficiency
    




Placing a B12 tablet under your tongue produces results similar to muscular injections with fewer complications.

Image Credit: OksanaKiian/iStock/GettyImages

Image Credit: OksanaKiian/iStock/GettyImages

Even high doses of vitamin B12 are considered safe, and side effects are rare. There have, however, been cases of people experiencing the allergic reaction known as anaphylaxis after taking B12, underscoring the importance of talking to your doctor before including B12 in your health regimen.

      Nutrients: Foods and Supplements Associated with Vitamin B12 Biomarkers among Vegetarian and Non-Vegetarian Participants of the Adventist Health Study-2 (AHS-2) Calibration Study
    
      Nutrients: Vitamin B12-Containing Plant Food Sources for Vegetarians
    
      National Institutes of Health: Vitamin B12
    
      Cureus: Anaphylactic Reaction to Cyanocobalamin
    
      Nutrition Reviews: Vitamin B12 in Meat and Dairy Products
    
      Journal of Nutritional Science and Vitaminology: Loss of Vitamin B12 in Fish (Round Herring) Meats During Various Cooking Treatments
    
      Nutrients: Vitamin B12 Among Vegetarians
    
      Food Fortification in a Globalized World: Efficacy and Safety of Vitamin B12 Fortification
    
      New Zealand Medical Journal: Sublingual Vitamin B12 Compared to Intramuscular Injection in Patients With Type 2 Diabetes Treated With Metformin
    
      European Journal of Clinical Nutrition: Treatment of Vitamin B12 Deficiency-Methylcobalamine? Cyancobalamine? Hydroxocobalamin?-Clearing the Confusion
    
      Clinical Nutrition: Effect of Two Different Sublingual Dosages of Vitamin B12 on Cobalamin Nutritional Status in Vegans and Vegetarians With a Marginal Deficiency