B12 is an essential vitamin, which means your body needs it to function properly. Getting enough vitamin B12 is important for your overall health, as it’s a necessary nutrient for processes involving the central nervous system, DNA, and red blood cells. Your body can’t produce the vitamin on its own, so you must get B12 from your diet or supplements.
However, an estimated 6% of the U.S. population under the age of 60 is vitamin B12 deficient. Deficiency rates are much higher in certain populations, including people over 60 and those taking certain medications, such as metformin, a drug that lowers blood sugar levels.
Vitamin B12 deficiency can have major effects on the body, but it can be detected, treated, and in some cases, prevented entirely.
B12 requirements change throughout life. As with many other nutrients, babies and children need less B12 each day than adults.
The recommended daily intake of B12 in micrograms (mcg) is:
- Up to 6 months: 0.4 mcg
- 7 to 12 months: 0.5 mcg
- 1 to 3 years: 0.9 mcg
- 4-8 years: 1.2 mcg
- 9-13 years: 1.8 mcg
- 14-18 years: 2.4 mcg
- Age 19 and over: 2.4 mcg
It’s important to keep in mind that the recommended daily intake is based on the amount needed to avoid deficiency, meaning these recommendations are not necessarily what the average adult needs to maintain optimal vitamin B12 levels.
For example, studies have shown that to maintain healthy blood levels of vitamin B12, men need to consume 5.94 mcg per day and women over the age of 20 need to consume 3.78 mcg.
During pregnancy and breastfeeding, the requirements for most vitamins and minerals increase. Because B12 is involved in proper growth and development of the fetus, pregnant women need 2.6 mcg of B12 per day, and breastfeeding women need 2.8 mcg per day. However, some experts recommend that breastfeeding women take more B12 than currently recommended to maintain optimal blood levels of the vitamin.
Vitamin B12 deficiency during pregnancy can be harmful to both parents and the fetus. A lack of vitamin B12 during this time can lead to adverse effects, including abnormal fetal development and preeclampsia, a dangerous condition characterized by high blood pressure.
There are several factors that can cause vitamin B12 deficiency, some of which are beyond an individual’s control.
There are three main causes of B12 deficiency:
- Autoimmune problems: Pernicious anemia is an autoimmune disease that makes it difficult for the small intestine to absorb vitamin B12, which leads to low vitamin B12 levels.
- Malabsorption: Some people may not be able to absorb vitamin B12 effectively due to intestinal damage or surgery. For example, people who have had gastric bypass surgery or have had part of their intestine removed may be at risk for developing vitamin B12 deficiency.
- Low dietary intake: Vitamin B12 is found in foods of animal origin, such as fish, meat, poultry, eggs, and dairy products. Not getting enough vitamin B12-rich foods in your diet can lead to a vitamin B12 deficiency, which is common in people who have been following a vegan or strict vegetarian diet for at least several years.
Long-term use of certain medications has also been linked to vitamin B12 deficiency. Metformin, which lowers blood sugar levels, and proton pump inhibitors, which treat acid reflux, are examples of medications that can interfere with the absorption of vitamin B12 and lead to vitamin B12 deficiency.
Some people are more likely than others to develop vitamin B12 deficiency due to factors such as age and underlying medical conditions, and certain factors, such as the use of certain medications, may increase your risk of vitamin B12 deficiency.
Risk factors for B12 deficiency include:
Be 60 years of age or older
The risk of vitamin B12 deficiency increases with age. This is due to malabsorption and loss of intrinsic gastric factor, a substance required for vitamin B12 absorption. Up to 20% of U.S. adults over 60 years of age are thought to be vitamin B12 deficient.
Taking certain medications
Some medications, such as metformin and proton pump inhibitors, can negatively affect the absorption of vitamin B12, so long-term use of these medications can lead to vitamin B12 deficiency.
Have certain health conditions
People with certain health conditions are more likely to develop vitamin B12 deficiency. These conditions include inflammatory bowel disease (IBD) and celiac disease. These diseases make it difficult to absorb vitamin B12.
Vegan Diet
Because B12 is found in high amounts in animal products like meat and fish, people who follow a vegan or vegetarian diet are more likely to develop a B12 deficiency, and the risk is even higher for those who have followed such a diet for at least three years. However, there are supplements and non-animal sources of vitamin B12, such as fortified cereals, that can prevent vitamin B12 deficiency in these groups.
Having certain surgeries
Surgeries such as gastric bypass, ileectomy (removal of the end of the small intestine and the beginning of the colon), and gastrectomy (removal of part or all of the stomach) can affect the body’s ability to absorb vitamin B12.
Are pregnant or breastfeeding
Because the need for vitamin B12 increases during pregnancy and breastfeeding, pregnant and breastfeeding people are at higher risk of low vitamin B12 levels.
Alcohol and drug abuse
Research has shown that alcohol abuse and use of certain drugs, such as methamphetamines, may increase the risk of vitamin B12 deficiency, which may be caused by inadequate intake and reduced absorption of vitamin B12 from the diet.
Some of the most common symptoms of B12 deficiency are vague, so many people may not realize they have a deficiency, which is why it’s essential to get a blood test to evaluate your B12 levels if you think you may have a deficiency.
The most common symptoms of B12 deficiency include:
- Malaise
- Pale skin
- Pale conjunctiva (the tissue lining the eyelids)
- Shortness of breath during activity
- Dry lips
Inflammation of the tongue (glossitis) can be another sign of vitamin B12 deficiency.
B12 deficiency can also cause neurological symptoms such as:
- dizzy
- Memory problems
- headache
- Tingling in the hands and feet
- Difficulty walking
B12 deficiency can lead to more severe symptoms, such as nerve damage, which can be irreversible if left untreated.
B12 deficiency is diagnosed by blood tests such as a complete blood count, which includes testing the levels of B12 and folate in your serum. Your health care provider may also order other laboratory tests, such as tests to measure methylmalonic acid and homocysteine levels. These two measurements help diagnose B12 deficiency.
People with serum vitamin B12 levels below 200 picograms per milliliter (pg/mL) are considered deficient. People with serum vitamin B12 levels between 200 and 300 pg/mL are considered to be borderline deficient or have low vitamin B12 levels. Up to 40% of the Western population has borderline vitamin B12 levels.
Levels above 300 pg/mL are considered normal, but people with lower-than-normal levels may also experience symptoms of vitamin B12 deficiency.
If you’ve been diagnosed with B12 deficiency or your B12 levels are below the normal range, your healthcare provider will recommend a treatment plan tailored to your needs.
Because B12 deficiency shares symptoms with other serious conditions and illnesses, it is important to never self-diagnose and always contact your healthcare provider for appropriate testing to rule out a deficiency.
If your B12 levels are found to be low or deficient, your healthcare provider may recommend either oral B12 supplements or B12 injections.
Your health care provider can also help manage any underlying health conditions that may be causing vitamin B12 deficiency.
People who don’t get enough vitamin B12 in their diet can boost their vitamin B12 levels by taking an oral vitamin B12 supplement in the form of a spray, capsule, or lozenge. However, for people who are unable to properly absorb vitamin B12 due to a medical condition or previous surgery, vitamin B12 injections are recommended.
Dosage and duration vary depending on the severity of the deficiency and the underlying cause.
While some causes of B12 deficiency cannot be prevented, most people can maintain optimal B12 levels by consuming foods that contain B12 or by supplementing their diet with B12.
If you’re interested in taking a B12 supplement, it’s a good idea to have your B12 levels checked by a healthcare professional beforehand, and then ask for advice on dosage to ensure you’re getting the right amount of B12.
Vitamin B12 is found in multivitamins, as well as vitamin B-complex and vitamin B12-only supplements. Multivitamins generally contain less vitamin B12 than supplements that contain only vitamin B12.
Most vitamin B12-only supplements contain 500 to 1,000 micrograms per serving. Vitamin B12 supplements are generally considered safe, even at very high doses, because your body doesn’t store too much vitamin B12 and excretes what it doesn’t need in your urine.
In fact, because vitamin B12 has such low toxicity, there is no tolerable upper intake level (maximum daily intake of a nutrient that is unlikely to cause harm).
It’s important to note that some forms of vitamin B12 are more effective than others at raising vitamin B12 levels. Research has shown that natural forms of vitamin B12, such as methylcobalamin, may be more effective at raising vitamin B12 levels compared to cyanocobalamin, a synthetic form of vitamin B12.
If you’re concerned that you’re not getting enough vitamin B12 in your diet, try increasing your intake of the following foods that are rich in vitamin B12:
- Boiled beef liver
- Boiled clams with shells removed
- Fish such as salmon and tuna
- Dairy products such as yogurt and cheddar cheese
- egg
- Poultry like turkeys
B12 is primarily concentrated in animal foods, but is also found in some plant foods, such as fortified foods. If you are consuming a plant-based diet with little or no animal products, be sure to include more fortified foods in your diet to meet your B12 needs.
Plant-based sources of vitamin B12 include:
B12 deficiency can be caused by a variety of factors, including medical conditions, medication use, or low dietary intake of the vitamin.
A B12 deficiency can cause a variety of vague symptoms, including fatigue and pale skin. If left untreated, a deficiency can have serious health effects.
Most people can maintain optimal vitamin B12 levels by regularly consuming foods rich in vitamin B12, such as fish, eggs, and yogurt, but some people may need to take vitamin B12 supplements or receive vitamin B12 injections to treat and prevent deficiencies.
If you’re concerned that you may have a B12 deficiency or deficiency, make an appointment with your healthcare provider, who can order blood tests to rule out a deficiency and give you treatment recommendations based on your current B12 levels.
