Vitamin B12

Vitamin B12 is an important vitamin needed for a healthy nervous system, the formation of red blood cells, and for building DNA. Together with other micronutrients it plays an important role in cell metabolism and can only be obtained from animal-derived foods.

A lack of vitamin B12 can lead to health problems and severe symptoms if it’s not properly managed. So it’s important to maintain normal levels of vitamin B12. Let’s find out the exact role of vitamin B12 and how we can make sure our bodies get enough of it to stay healthy.

Vitamin B12 is also known as cobalamin and one of the most important micronutrients. It is a water-soluble vitamin, meaning that it can dissolve in water. In the human body, B12 vitamin is needed for healthy blood and growth, and normal brain and nerve function, and children need it for healthy development. 1

Only certain bacteria can produce vitamin B12, some of which live in the intestines of ruminants, like cattle, or other animals. 2 These animals absorb vitamin B12 made available by bacterial digestion and store it in their liver and muscles, or pass it into their eggs and milk.

Vitamin B12 binds to proteins. When we eat food that contains it, our stomach acid releases the B12 vitamin, so it’s ready for the next step of absorption which involves binding it to intrinsic factor (IF). IF is a glycoprotein produced in the stomach that helps us to absorb B12. People who take acid-blocking medication or lack IF are at risk of a vitamin B12 deficiency. 3

Getting enough vitamin B12 benefits our health in several ways. It is involved in the following vital processes:

• red blood cell formation, preventing anemia
• normal function of the nervous system and brain
• cognitive function
• energy production from food
• helping to create and regulate DNA, the molecule which carries genetic information
• healthy skin and eyes
• normal child development, preventing birth defects.

Playing an essential role in so many processes, our body is able to store a certain amount of vitamin B12, mostly in the liver. In adults, the body can store 2-3 mgs which lasts for 3 to 5 years.

In recent years, researchers thoroughly investigated the best positive vitamin B12 effects on our health. Studies examined whether vitamin B12 prevents heart and blood vessel conditions through its potential to decrease homocysteine blood levels. Homocysteine is an amino acid which may increase the risk of heart attack when its blood levels are elevated. Researchers found that along with vitamins B6 and B9, B12 supplementation has significant risk reductions for stroke patients. However, they could not prove any beneficial effects for cardiovascular conditions. 4

Animal-derived foods contain vitamin B12, as it is produced by microorganisms in their intestines. Plants do not need vitamin B12 and thus do not produce or contain it. Some manufacturers however, fortify plant products with vitamin B12, meaning that they add extra vitamin B12 to the foods.

The following vitamin B12 foods can help you get the recommended daily amount: 5

• fish
• meat, poultry
• eggs
• beef liver
• milk and dairy products
• fortified products such as breakfast cereals, nutritional yeasts, soy or oat milk.

Some algae or fermented products like miso and tempeh contain substances that are chemically similar to vitamin B12. Our body cannot use these substances in the same way as the actual B12 vitamin and therefore, these foods are not reliable vitamin B12 sources.

A lack of the B12 vitamin is rare, as most people get enough of it through their diet. However, people who follow strict plant-based diets need to ensure that they obtain enough vitamin B12 from fortified sources or supplements. Older adults may also be advised to take vitamin B12. Their stomachs produce less hydrochloric acid which leads to a reduced absorption of the vitamin.

People with digestive tract conditions affecting nutrient absorption may be unable to absorb sufficient levels of B12 from food. Risk conditions include coeliac disease, Crohn’s disease or gastric bypass surgery. To prevent vitamin B12 deficiency, these people may need to supplement with up to 1000 mcg of vitamin B12 per day. 6

Certain medications may also lead to B12 deficiency. Metformin for blood sugar control or proton pump inhibitors can affect B12 absorption. People who regularly take such medications may think about talking to their doctor about taking vitamin B12 supplements.

A vitamin B12 test is useful for people who are at risk of developing a B12 deficiency. If you experience any of the conditions described, you may think about testing your blood levels of vitamin B12. If you experience symptoms of a B12 deficiency, a test may also be useful.

Furthermore, pregnant and lactating women may think about testing their B12 levels, as they require a higher dose.

Visit Ada's article about vitamin deficiency tests to find out more.

Q: What is the B12 vitamin and what are the benefits?

Vitamin B12 is a water-soluble vitamin which is important for many processes in the human body. It is required for a healthy nervous system, blood cell formation, and DNA creation. Only animal foods and dairy products contain vitamin B12.

Q: When to take vitamin B12?

People who only eat plant-based food and older adults should supplement with vitamin B12. People with certain medical conditions concerning the gastro-intestinal system which may lead to a vitamin B12 deficiency, may also be at risk of vitamin B12 deficiency. Supplementation can be performed with oral tablets or a vitamin B12 injection.

Q: What side effects can vitamin B12 cause?

There is no evidence that vitamin B12 produces side effects. A vitamin B12 overdose is unlikely, as any excess of the water-soluble vitamin can be excreted in the urine.

Q: How much vitamin B12 should I take?The recommended dietary allowance (RDA) for B12 is 2.4 mcg for adults. The vitamin B12 dosage for seniors is also 2.4 mcg per day. 7

Q: When do I need to seek medical help?

If you belong to a risk group of vitamin B12 deficiency, or feel any associated deficiency symptoms, you should seek medical help.