Vitamin B12 (Cobalamin) – Benefits, Sources, Deficiency Symptoms and Side Effects

vitamin b12

Vitamin B12, as the name implies, is part of the B complex of vitamins. Like the other B vitamins, it is involved in energy metabolism and other related biological processes.

However, that is where the similarity ends. The list of things that are unique about this vitamin is long, and includes the following facts:

  • Most B vitamins do not store well, but several years’ worth of vitamin B12 can be stored in your body
  • Most B vitamins can be found in a wide variety of plant and animal foods, but since no plant or animal can make vitamin B12 (only microorganisms like fungi and bacteria can do that), it is typically only animal foods that contain B12 since plants cannot make or store this vitamin. However, mushrooms (since they are themselves fungi) often contain B12, as do fermented plant foods like tempeh or miso since they have been produced with the help of microorganisms. Most B vitamins are relatively small and have a fairly simple chemical structure, while vitamin B12 is larger and more complex.
  • Most B vitamins are more easily absorbed than vitamin B12,which has more complicated requirements for absorption.
  • In terms of physical amount, vitamin B12 has the lowest daily requirement of all the B vitamins, and it is needed in about 1/1000th the amount of some other B vitamins.
  • Vitamin B12 is the only vitamin that contains a metal element (cobalt). In fact, the cobalt contained in B12 is the reason that this vitamin goes by the chemical name cobalamin.



  • Helps Maintain Energy Levels

Cobalamin benefits your metabolism because it’s needed to convert carbohydrates into useable glucose in the body. Glucose from carbohydrate foods is used as a form of energy, so this is the reason why people with vitamin B12 deficiencies often experience fatigue. Cobalamin is also needed for neurotransmitter signaling that helps your muscles contract and gives you energy to go about your day without feeling tired and run down.

  • Prevents Memory Loss and Lowers Risk of Neurodegenerative Disease

A vitamin B12 deficiency may cause various neurologic and psychiatric disturbances. Because of its role in nerve health and neurotransmitter signaling, Cobalamin benefits cognitive function and is used to lower the risk of neurodegenerative diseases, including Alzheimer’s disease and dementia.

  • Boosts Mood and Helps the Nervous System to Properly Function

One of the most researched Cobalamin benefits is its ability to help in healthy regulation of the nervous system, including reducing such mood disorders as depression and anxiety. Vitamin B12, along with folate, is needed as a major determinant of one-carbon metabolism, which produces the compound called SAM (S-adenosyl methionine). SAM is crucial for neurological function, dealing with stress and mood regulation.

B12 is needed for concentration and cognitive processes, such as learning, so a vitamin B12 deficiency can result in difficulty focusing and an increased risk for attention disorders.

  • Plays a Role in Maintaining Heart Health

Vitamin B12 benefits cardiovascular health in several ways, which is important considering the fact that heart disease is currently the number one cause of death worldwide. Cobalamin helps to reduce elevated homocysteine levels, which is now considered a major risk factor for heart disease. Homocysteine is an amino acid and its levels in the blood are influenced by blood levels of B-complex vitamins, including vitamin B12.

Vitamin B12 helps to protect against heart disease like a heart attack or stroke by lowering high homocysteine levels in the blood. There is also some evidence that B12 can help control high cholesterol and high blood pressure levels. B vitamins are also able to control atherosclerotic diseases, in which someone experiences a dangerous build-up of plaque in the arteries.

  • Needed for Healthy Skin and Hair

Vitamin B12 is essential for healthy skin, hair and nails because it plays a major part in cell reproduction. Vitamin B12 benefits skin health by reducing redness, dryness, inflammation and acne blemishes — and can be applied to the skin for psoriasis and eczema. It can also reduce hair breakage and help nails to become stronger.

  • Aids in Digestion

Due to its role in helping with digestive enzyme production, vitamin B12 is needed to support a healthy metabolism and the breakdown of foods within the stomach. One of the ways that vitamin B12 benefits digestion? It helps foster healthy bacteria within the gut environment. The elimination of harmful bacteria in the digestive tract — and simultaneously the presence of beneficial bacteria — is what prevents digestive disorders like inflammatory bowel disease (IBS) or Candida.

  • Needed for a Healthy Pregnancy

Vitamin B12 is needed to create nucleic acid, or DNA — the basic genetic material that’s used to create the entire body. Therefore, vitamin B12 is not only a key nutrient for growth and development, but a vital component of a healthy pregnancy. Vitamin B12 also interacts with folate in the body, so it may help lower the risk of birth defects, such as neural tube defects.

  • May Help Prevent Cancer

Vitamin B12 supplementation is now being studied as a way to help lower the risk of certain kinds of cancers, especially when taken with folate. Some preliminary research shows that vitamin B12 benefits the immune system enough to potentially help prevent cancer, including cervical, prostate and colon cancers.

  • Helps Produce Red Blood Cells and Prevent Anemia

B12 is needed to help produce a healthy level of red blood cells. It helps prevent a type of anemia called megaloblastic anemia, which results in symptoms like chronic fatigue and weakness.


Deficiency Symptoms

·         Constantly feeling tired or chronic fatigue

·         Muscle aches and weakness

·         Joint pain

·         Difficulty breathing or shortness of breath

·         Feeling dizzy

·         Poor memory

·         Inability to concentrate well

·         Mood changes, like increased depression and anxiety

·         Having abnormal heart problems, such as palpitations

·         Poor dental health, including bleeding gums and mouth sores

·         Digestive problems like nausea, diarrhea or cramping

·         A poor appetite

·         A more serious deficiency can also cause a form of anemia called pernicious anemia, a serious condition that can cause memory loss, confusion and even long-term dementia



Good sources include:

  • meat
  • salmon
  • cod
  • milk
  • cheese
  • eggs
  • some fortified breakfast cereals


World’s Healthiest Foods ranked as quality sources of vitamin B12

Food Serving
Cals Amount
Sardines 3.20 oz 188.7 8.11 338 32.2
Salmon 4 oz 157.6 5.67 236 27.0
Tuna 4 oz 147.4 2.66 111 13.5
Cod 4 oz 96.4 2.62 109 20.4
Lamb 4 oz 310.4 2.51 105 6.1
Scallops 4 oz 125.9 2.44 102 14.5
Shrimp 4 oz 134.9 1.88 78 10.4
Beef 4 oz 175.0 1.44 60 6.2
Yogurt 1 cup 149.4 0.91 38 4.6
Cow’s milk 4 oz 74.4 0.55 23 5.5
Eggs 1 each 77.5 0.55 23 5.3
Turkey 4 oz 166.7 0.42 18 1.9
Chicken 4 oz 187.1 0.39 16 1.6
Cheese 1 oz 114.2 0.24 10 1.6
Mushrooms, Crimini 1 cup 15.8 0.07 3 3.3


How much vitamin B12 do I need?

Adults need approximately 0.0015mg a day of vitamin B12.

If you eat meat, fish or dairy foods, you should be able to get enough vitamin B12 from your diet.

However, because B12 is not found naturally in foods such as fruit, vegetables and grains, vegans may not get enough of this vitamin. Read our page on the vegan diet for information and advice on vegan nutrition.


Side Effects

There is not enough evidence to show what the effects may be of taking high doses of vitamin B12 supplements each day.

Vitamin B12 absorption can be hindered when someone has a history of alcoholism or heavy smoking. In addition to alcohol and nicotine, long-term antibiotic use can also reduce the ability of the stomach to absorb and use vitamin B12. For this reason, anyone who has used stomach-acid controlling drugs may want to talk to their doctor about needing vitamin B12 supplements.

Potassium supplements can also reduce absorption of vitamin B12 benefits, so if you take large amounts of potassium in supplement form, you should watch out for a possible vitamin B12 deficiency. Potassium from food sources shouldn’t cause a problem, but very high amounts may set someone up for a vitamin B12 deficiency.



No Comments

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.