We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here’s our process.
Medical News Today only shows you brands and products that we stand behind.Our team thoroughly researches and evaluates the recommendations we make on our site. To establish that the product manufacturers addressed safety and efficacy standards, we:
- Evaluate ingredients and composition: Do they have the potential to cause harm?
- Fact-check all health claims: Do they align with the current body of scientific evidence?
- Assess the brand: Does it operate with integrity and adhere to industry best practices?
Vitamin B12 (cobalamin) is essential for the health of nerve tissue, brain function, and red blood cells. Sources include meat, eggs, and some yeast products. People with a B12 deficiency may need supplements. Signs of a deficiency include headaches and fatigue.
A deficiency or insufficiency can occur when levels of vitamin B12 become too low to meet the demands of the body. This can lead to a number of symptoms and can even progress to irreversible neurological issues if left untreated.
In the United States and United Kingdom, approximately
Vitamin B12 is a water-soluble vitamin, like all other B vitamins. This means it can dissolve in water and travel through the bloodstream. The body can store vitamin B12 for up to 4 years, and it can get rid of any excess or unwanted vitamin B12 in the urine.
Vitamin B12 is the largest and most structurally complicated vitamin. It occurs naturally in animal products like meat and eggs, and manufacturers can produce it through bacterial fermentation synthesis.
This article explores the functions of vitamin B12, how a person would know they are not consuming enough vitamin B12, and how to increase intake.
Vitamin B12 is crucial to various bodily processes,
- normal functioning of the brain and nervous system
- cognitive functioning (ability to think)
- formation of red blood cells and anemia prevention
- helping create and regulate DNA
- possibly preventing congenital abnormalities
- helping protect the eyes from macular degeneration
- necessary for energy production
Vitamin B12 is essential for healthy blood. When the body does not have enough B12, it leads to decreased normal red blood cell production (anemia), which impairs oxygen delivery.
Megaloblastic anemia, also called nutritional-deficiency anemia, is a type of anemia caused by B12 or folate deficiency. Megaloblastic anemia is characterized by impaired DNA synthesis and the formation of large, abnormal, immature red blood cells.
The National Institutes of Health (NIH) recommend that teens and adults over the age of 14 should consume
Excessive intake of vitamin B12 has not shown toxic or harmful qualities. However, people should speak with their physician before starting any new supplements.
Some medications may decrease the absorption of vitamin B12 from foods. These medications include:
Vitamin B12 occurs naturally in many animal products. It does not typically occur in plant foods, unless it is supplemented.
Good dietary sources of vitamin B12
- fish, especially haddock and tuna
- dairy products, such as milk, cheese, and yogurt
- some nutritional yeast products
Additionally, manufacturers fortify some types of plant milk and breakfast cereals with vitamin B12.
Even though vitamin B12 is found in a variety of foods, some people are at an increased risk of developing B12 deficiency or insufficiency. Groups at an increased risk include:
- older adults
- those on restrictive diets like vegan diets
- people with certain health conditions such as celiac disease
Having low or deficient B12 levels can lead to a number of symptoms, some of which can be serious. It can result in irreversible and
hat said, even slightly lower-than-normal levels of vitamin B12 can trigger symptoms. However, these symptoms are
Once symptoms worsen, they can include neurological changes, such as numbness and tingling in the hands and feet. Some people may have difficulty maintaining balance.
Infants who lack vitamin B12
- unusual movements, such as face tremors
- reflex problems
- feeding difficulties
- eventual growth problems if left untreated
Insufficient vitamin B12 can also lead to anemia. The most common symptoms of anemia are fatigue, shortness of breath, and an irregular heartbeat. People with anemia might also experience:
- a sore mouth or tongue
- weight loss
- pale or yellowing skin
- menstrual problems
Who is at risk?
Several groups of people may be at an
Vegans face a risk of vitamin B12 deficiency, as their diet excludes animal-sourced food products. Pregnancy and lactation can worsen deficiency in vegans. Unless a vegan diet is carefully planned, it is difficult to get enough vitamin B12 through plant foods alone. For this reason, it is recommended for those following vegan diets to supplement with B12.
People with pernicious anemia may lack vitamin B12. Pernicious anemia is an autoimmune disease that affects the blood. Patients with this disorder do not have enough intrinsic factor (IF), a protein in the stomach that allows the body to absorb vitamin B12.
Other at-risk groups include people with small intestine problems, for example, an individual with a surgically shortened small intestine. Crohn’s disease is also a
People with chronic alcohol use disorder may lack vitamin B12, as their bodies may not absorb nutrients efficiently.
Treatment for vitamin B12 deficiency includes oral vitamin B12 supplements or vitamin B12 injections.
Some people have difficulties absorbing vitamin B12 from food sources and may need to take supplements.
Some populations may have problems absorbing vitamin B12 from food, including:
- older adults
- people with pernicious anemia
- those with intestinal disorders
People can take B12 supplements orally or in a nasal spray. However, oral supplements
Vegans and others who do not get enough B12 from their diet can take supplements to avoid deficiency. This is particularly important during pregnancy and while breastfeeding.
People can purchase various B12 supplements in health food stores and online. That said, supplements are not FDA regulated and people should be careful when taking them, and ensure they purchase them from a reliable source.
Doctors may prescribe
These injections consist of vitamin B12 in cyanocobalamin or hydroxocobalamin forms.
A healthcare professional typically administers these injections into a muscle every other day for 2 weeks, or until the individual’s symptoms improve. Continuing treatment depends on if the cause of the deficiency relates to diet or if the individual has any accompanying neurological problems.
Hydroxocobalamin injections may cause side effects, including:
- pain, swelling, or itching at the injection site
- nausea or vomiting
- hot flashes
Vitamin B12 is an essential vitamin mainly found in animal products. Most adults require 2.4 mcg daily.
The body needs vitamin B12 for normal function of the brain and nervous system, the formation of red blood cells, and other critical processes.
Deficiencies in vitamin B12 can lead to symptoms like headaches, fatigue, and digestive problems and can even lead to nerve damage and cognitive issues.
Some people are more at risk of deficiencies, such as older adults and those who do not absorb nutrients well. Vegans may also have a deficiency risk, as their diet excludes many B12 sources.
Most people who eat a balanced diet receive enough B12. For others, doctors may recommend oral supplements or injections.