Does Vitamin B12 Increase Heart Rate?

What is vitamin B12?

Vitamin B12, also known as cobalamin, is an essential vitamin, meaning it is necessary for the healthy functioning of the body. It is involved in a lot of different processes that include, among others, red blood cell production, keeping nerves healthy and making DNA. The body cannot create vitamin B12, so it must be taken from various food sources, such as fish, meat, milk and fortified cereals. The average intake recommendation for vitamin B12 is 2.4 micrograms a day. The deficiency of vitamin B12 can begin mildly and progress to severe side effects, impairing brain and nerve function. 

Food sources of vitamin B12

The two most common causes of vitamin B12 deficiency. One is from not getting enough vitamin B12 through the diet. Most of food sources of vitamin B12 are animal products, meaning that vegetarians and vegans are often at increased risk of B12 deficiency. Also, as people grow older, 10-30% may be unable to absorb naturally occurring vitamin B12. 

Another cause of B12 deficiency is its impaired absorption in the gut, in such conditions as pernicious anemia, Crohn’s disease, celiac disease or surgeries that involve gastric bypass, and result in the lack of ‘intrinsic factor’; a gut molecule that helps vitamin B12 absorption. 

Some medications such as anticonvulsants and proton pump inhibitors, can also increase the likelihood of B12 deficiency through varied mechanisms. 

Complications of B12 deficiency

Vitamin B12 Deficiency can be difficult to diagnose, as it has similar symptoms to many other conditions. Because vitamin B12 has many different roles in the body, symptoms can vary a lot. B12 can cause 4 main conditions, which present in different ways:


B12 deficiency leads to a type of anemia called pernicious anemia. Anemia is when there is not enough hemoglobin and/or not enough red blood cells. Hemoglobin is contained in the red blood cells and function to oxygen from the lungs to all the cells in the body. If B12 levels are too low, the red blood cells produced will be faulty, meaning they are less able to carry oxygen.  

Anemia can lead to tiredness, dizziness, paleness (especially pale extremities such as fingers and toes) and increased heart rate. This can be made worse with the deficiency of necessary elements for manufacturing and production of red blood cells, for example, vitamin B12 or iron deficiency. 

Pernicious Anemia

Nerve damage 

Vitamin B12 is important for the functioning of the nervous system. When B12 levels are low, nerves can begin to slowly break down; a condition known as neuropathy, which simply signifies a problem with the nerves.

Symptoms include tingling, numbness, weakness, and difficulty keeping balance that may get worse with anemia.

Spinal cord damage 

Spinal cord damage, known as myelopathy (problem with the spinal cord), is also associated with vitamin B12 deficiency. Myelopathy results from the damage of nerve cells in a part of the spinal cord. These nerve cells are in charge of coordinating muscle movement along with perceiving and telling your body about the sensations you are experiencing from the outside world. Symptoms of myelopathy include muscle weakness, numbness, tingling, difficulties sensing touch and balance problems. 


Dementia is a disease most commonly presenting in the elderly, and may be exacerbated by vitamin B12 deficiency. Symptoms of dementia include memory loss, behavioral changes, cognitive decline, and judging impairment. 

Symptoms of vitamin B12 deficiency

Other various symptoms of B12 deficiency include:

  • A swollen, inflamed tongue
  • Dizziness
  • Shortness of breath
  • Pale skin 
  • Muscle weakness
  • Numbness or tingling in hands and feet 
  • Tiredness (low energy)
  • Weight loss 
  • Infertility
  • Irregular or increased heartbeats
  • Constipation
  • Appetite loss
  • Flatulence
  • Low mood (depression)
  • High blood pressure or very low blood pressure 

Vitamin B12, Vitamin B6 and Folate 

There is a strong interrelationship between vitamin B12, vitamin B6 and folate (also known as vitamin B9). A combined deficiency of these 3 members of vitamin B complex is related to elevated homocysteine (an amino acid; a unit that with other amino acids form proteins) levels that are‌ associated with an increased risk of stroke.

Having a diet deficient in B6 results in vitamin B12 levels lowering.

B12 deficiency can decrease folate levels in the cells even if folate intake remains the same. If folate levels are low, they can be normalized either using folic acid tablets or through dietary manipulation to increase such foods as broccoli, brussels sprouts and peas. 

How does B12 affect the heart rate?

Less than the normal dietary intake of B12 can increase the incidence of palpitations (perceived sensation of increased or irregular heart beating), which makes you feel your heart beating in your chest, seemingly speeding up or running at an irregular rhythm. 

Vitamin B12 supplements (not clear if this refers to physiological or pharmacological doses) lower the blood levels of homocysteine in the blood, which may be linked to increased risk of stroke or heart attacks, although the relation between vitamin B12 supplementing and lower rates of heart attacks has not been confirmed.  

Side effects of too much vitamin B12

You can take vitamin B supplements in several forms, ranging from over-the-counter medications. If B12 levels are very low, injections are usually given first to be followed for maintenance by either tablets or injections. 

Heart effects

Vitamin B12 injections are likely to cause side effects as a large ‘amount’ of vitamins is put directly into the bloodstream. Excess vitamin B12 can result in the possibility of blood clots overly and unduly forming in important blood vessels. Blood clots can stop the blood flowing to different body organs, leading ultimately to widespread organ damage resulting in devastating consequences, as strokes and possibly heart attacks. 

Liver and kidney effects

The liver and kidneys are responsible for breaking down lots of molecules, including vitamin B12. If the levels of vitamin B12 are too high, the liver and kidney cells may be damaged with inflammation and scarring. 

When to seek medical advice

Those on restricted diet, or have had gastric bypass surgery, and those who are pregnant or with certain health conditions may be at more risk of B12 deficiency to be confirmed by a blood test. 

Those with a history of heart, liver or kidney problems should consult their doctor before taking over-the-counter B12 supplements. 


Vitamin B12 is an important vitamin that you can get through diet or supplements. Getting enough vitamin B12 can increase energy levels, lift mood, prevent loss of neurons, help with high blood pressure, support bone health, prevent major birth defects and prevent anemia. If you are at increased risk of B12 deficiency, supplements are one way to increase B12 intake after being approved by a medical professional. 


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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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