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Vitamin B12 Injections:

Good or Bad?

  • Vitamin supplements are very popular.

  • People often believe they'll act as a safety net and help to ensure adequate nutrient intake.

  • Supplementing with vitamin B12 is particularly common, because deficiency is widespread.

  • In fact, many people regularly get injections with vitamin B12.

  • These are claimed to help with energy levels, brain function and weight loss, to name a few.

What is Vitamin B12 and What Does it Do?

  • Vitamin B12 is a water-soluble vitamin, also known as cobalamin.

  • It plays a vital role in brain function and the production of DNA and red blood cells.

  • Chemically, vitamin B12 can exist in a number of different forms, but all of them contain the mineral cobalt.

  • The vitamin can be stored in the liver for a long time, so it may take a few years for a deficiency to develop.

Many People Are Deficient

  • The recommended daily intake (RDI) of vitamin B12 is 6 micrograms per day. 

  • Deficiency is common, especially in people who follow a vegetarian or vegan diet.

  • In fact, it's thought that up to 90% of people following these diets have a deficiency. 

  • This is because B12 is only found naturally in animal foods.

  • However, vegans and vegetarians are not the only ones who are deficient. Even some meat eaters don't absorb it very well.

  • Unlike other vitamins, the absorption of vitamin B12 depends on a protein produced in your stomach, called intrinsic factor.

  • Intrinsic factor binds to vitamin B12, so that you can absorb it into the blood. People who don't produce enough intrinsic factor can become deficient.

  • Other people at risk of deficiency include those who have had intestinal surgery, including weight loss surgery. Those with diseases that affect the gut, such as Crohn's disease or celiac disease, are also at risk.

  • Those at greatest risk of vitamin B12 deficiency are vegans and vegetarians, who get little to no B12 from the diet. Deficiency can also be caused by poor absorption.

Vitamin B12 Shots Are Very Effective

  • An untreated vitamin B12 deficiency can lead to neurological problems or pernicious anemia, which occurs when your body doesn't have enough B12 to produce the amount of red blood cells it needs.

  • Vitamin B12 shots are the most common way to prevent or treat a deficiency. The injections are prescribed by a doctor and given intramuscularly, or into muscle.

  • Injections are usually given as hydroxocobalamin or cyanocobalamin. These are very effective at raising blood levels of B12 and preventing/reversing a deficiency.

Potential Health Benefits

  • Given the vital roles that vitamin B12 plays in your body, a deficiency can have serious health consequences.

  • In fact, low blood levels of the vitamin have been linked to several health problems.

Brain Function

  • Low levels of vitamin B12 have been linked to a decline in brain function.

  • Two recent reviews found that there may be a link between low blood levels and the development of dementia.

  • However, results have been mixed and treatment with vitamin B12 wasn't effective at improving brain function in people with normal brain.


  • It's been suggested that there may be a link between low vitamin B12 levels and depression.

  • However, one review found that treating depression with vitamin B12 didn't reduce the severity of symptoms.

  • Nevertheless, it was suggested that taking the vitamin on a long-term basis could help prevent a relapse into depression.

  • Currently, there is a lack of quality research in this area. Higher quality studies are needed to find out if there is a link between vitamin B12 and depression.

Age-Related Macular Degeneration

  • Age-related macular degeneration is a condition that causes you to gradually lose central vision, usually in both eyes.

  • In people aged 50 and over, adequate consumption of vitamin B12 is thought to be important for maintaining good vision and protecting against macular degeneration.

Some Other Claims

  • Recently, vitamin B12 injections and infusions have become popular among healthy people who don't appear to have a deficiency.

  • Advocates of this approach claim that regular injections can boost energy levels and help with weight loss and mood.

  • However, there is little to no evidence to support these claims.

  • Ensuring that you have enough vitamin B12 is important for brain function and mental, bone and eye health. Injections are probably useless if you don't have a deficiency.

Safety and Side Effects

  • Vitamin B12 injections are generally considered to be very safe. They have no major side effects.

  • However, in very rare cases, some people can experience side effects caused by allergic reactions or sensitivity.

  • If you experience any side effects, speak with your doctor.

  • Vitamin B12 injections are very safe. In rare cases, the injections may cause allergic reactions.

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