Vitamin B12

October 3, 2020

Overview

Vitamin B12 is an essential vitamin. This means that the body requires vitamin B12 to work properly. Vitamin B12 can be found in foods such as meat, fish, and dairy products. It can also be made in a laboratory. It is often taken in combination with other B vitamins.

Vitamin B12 is most commonly used for vitamin B12 deficiency, a condition in which vitamin B12 levels in the blood are too low, as well as cyanide poisoning and high levels of homocysteine in the blood (hyperhomocysteinemia).

Classification

Is a Form of:

Vitamin

Primary Functions:

Vitamin B12 deficiency

Also Known As:

B12, B Complex Vitamin, Bedumil

How Does It Work?

Vitamin B12 is required for the proper function and development of the brain, nerves, blood cells, and many other parts of the body.

Uses

A rare inherited condition marked by vitamin B12 deficiency (Imerslund-Grasbeck disease). Injecting vitamin B12 as a shot for 10 days followed by monthly injections for the remainder of life is effective for treating people with an inherited disease that results in poor absorption of vitamin B12.
Vitamin B12 deficiency. Vitamin B12 can treat and prevent vitamin B12 deficiency. It can be taken by mouth, as a shot, or through the nose. The shot works best in people with severe vitamin B12 deficiency or associated nerve damage.
Cyanide poisoning. Administering hydroxocobalamin (Cyanokit), a natural form of vitamin B12, as a shot for a total dose of up to 10 grams is likely an effective treatment for cyanide poisoning. Treatment of cyanide poising with hydroxocobalamin (Cyanokit) has been approved by the U.S. Food and Drug Administration (FDA).
High levels of homocysteine in the blood (hyperhomocysteinemia). Taking vitamin B12 by mouth, along with folic acid and sometimes pyridoxine (vitamin B6), can lower blood levels of homocysteine.
An eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD). Some research shows that taking vitamin B12 with other B vitamins, including folic acid and vitamin B6, might help prevent an eye disease called age-related macular degeneration. But the effects of vitamin B12 alone on AMD are not clear.
Canker sores. Using an ointment containing vitamin B12 helps to reduce pain of canker sores. Also, early research shows that taking vitamin B12 1000 mcg under the tongue (sublingually) might help to reduce the number of canker sore outbreaks, the duration of outbreaks, and pain caused by the canker sores.
Nerve pain caused by shingles (postherpetic neuralgia). Some research shows that injecting vitamin B12 in the form of methylcobalamin under the skin six times weekly for up to 4 weeks reduces pain more than taking vitamin B12 by mouth or injecting lidocaine under the skin in people with nerve damage from shingles. Other research shows that it reduces pain and the need for painkillers. Adding thiamine or lidocaine to the treatment also seems to reduce itching.

Recommended Dosing

The following doses have been studied in scientific research:

ADULTS:

BY MOUTH:

The typical general supplemental dose of vitamin B12 is 1-25 mcg per day: The recommended dietary allowances (RDAs) of vitamin B12 are: 1.8 mcg; older children and adults, 2.4 mcg; pregnant women, 2.6 mcg; and breast-feeding women, 2.8 mcg. Because 10% to 30% of older people do not absorb food-bound vitamin B12 efficiently, those over 50 years should meet the RDA by eating foods fortified with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 mcg per day has been used to maintain vitamin B12 levels in older people.
For vitamin B12 deficiency: Vitamin B12 doses of 300-10,000 mcg daily have been used. However, some evidence suggests that the most effective oral dose is between 647-1032 mcg daily.
For high levels of homocysteine in the blood (hyperhomocysteinemia): Vitamin B12 doses of 400-500 mcg in combination with 0.54-5 mg of folic acid and 16.5 mg of pyridoxine has been used.
For an eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD): A combination of 1 mg of vitamin B12, 2.5 mg of folic acid, and 50 mg of pyridoxine daily has been used for 7.3 years.

APPLIED TO THE SKIN:

For canker sores: A topical ointment containing vitamin B12 500 mcg daily in four doses for 2 days has been used.

AS AN INJECTION:

For vitamin B12 deficiency: The usual dose is 30 mcg as an injection into the muscle or under the skin daily for 5-10 days. For maintenance therapy, 100-200 mcg once monthly is commonly used. Both cyanocobalamin and hydroxocobalamin forms are used. The usual dose for pernicious anemia-associated vitamin B12 deficiency is 100 mcg given as an injection into the muscle or under the skin once daily for 6-7 days. Then the dose may be given every other day for 7 doses followed by every 3-4 days for around 3 weeks. Then, 100 mcg should be injected every month for life. Another dosing recommendation for injectable vitamin B12 includes 1000 mcg daily for 7-10 days followed by 1000 mcg weekly for 1 month followed by 1000 mcg monthly for life.
For rare inherited condition marked by vitamin B12 deficiency (Imerslund-Grasbeck disease): Vitamin B12 in the form of hydroxocobalamin has been injected into the muscle at a dose of 1 mg daily for 10 days followed by once monthly for the remainder of the person's life.
For cyanide poisoning: Hydroxocobalamin (Cyanokit) has been given intravenously (by IV) for a total dose of up to 10 grams.

USED IN THE NOSE:

For vitamin B12 deficiency: Doses of 500 mcg of vitamin B12 have been injected into one nostril weekly.

APPLIED UNDER THE SKIN:

For nerve pain caused by shingles (postherpetic neuralgia): As an injection under the skin, 1000 mcg of vitamin B12, with or without 100 mg of thiamine or 20 mg of lidocaine, has been given six times weekly for up to 4 weeks.

PLACED UNDER THE TONGUE:

For canker sores: Vitamin B12 1000 mcg daily under the tongue for 6 months has been used.

CHILDREN:

BY MOUTH:

The recommended dietary allowances (RDAs) of vitamin B12 are: Infants 0-6 months, 0.4 mcg; infants 7-12 months, 0.5 mcg; children 1-3 years, 0.9 mcg; children 4-8 years, 1.2 mcg; children 9-13 years, and 1.8 mcg; older children.

AS AN INJECTION:

For vitamin B12 deficiency: Injecting 0.2 mcg/kg of vitamin B12 into the muscle or under the skin once daily for 2 days, followed by a 1000 mcg injection daily for 2-7 days and another 100 mcg injection weekly for 4 weeks thereafter has been used. Additional injections of 100 mcg monthly may be needed depending on level of symptom improvement and cause of vitamin B12 deficiency.

Vitamin B12 Supplements Frequently Asked Questions

How much B 12 should you take a day?

While the recommended daily amount of vitamin B-12 for adults is 2.4 micrograms, you can safely take higher doses. Your body absorbs only as much as it needs, and any excess passes through your urine. High doses of vitamin B-12, such as those used to treat a deficiency, might cause: Dizziness.

What is the best supplement for vitamin b12?

Cyanocobalamin is a synthetic form of vitamin B12 that can be converted to the natural forms methylcobalamin and adenosylcobalamin. The body may absorb cyanocobalamin better, while methylcobalamin has a higher retention rate.

Is it OK to take 1000 mcg of b12 a day?

Because it's relatively safe, no tolerable upper intake level (UL) has been set for vitamin B12. UL is considered the maximum amount of a substance that can be taken safely without side effects. High doses of B vitamins over 1,000 mcg have also been associated with complications in people with kidney disease.

Are vitamin b12 supplements effective?

Studies have shown that vitamin B12 helps decrease homocysteine levels, which may reduce your risk of heart disease. However, there is currently no scientific evidence to confirm that vitamin B12 supplements are effective in this regard.

When should I take b12 morning or night?

B vitamins tend to boost energy, so take them in the morning; at night, they can lead to restlessness and insomnia. They're best absorbed on an empty stomach, but if you have a sensitive tummy, take them with a little food.

How long does it take for b12 supplements to work?

A response usually is seen within 48 to 72 hours, with brisk production of new red blood cells. Once B12 reserves reach normal levels, injections of vitamin B12 will be needed every one to three months to prevent symptoms from returning.

How can I increase my b12 naturally?

To increase the amount of vitamin B12 in your diet, eat more of foods that contain it, such as:

Beef, liver, and chicken.
Fish and shellfish such as trout, salmon, tuna fish, and clams.
Fortified breakfast cereal.
Low-fat milk, yogurt, and cheese.

How much vitamin b12 should a person over 65 take?

Why Low Vitamin B12 Levels Are Common in Older Adults

The recommended daily allowance for vitamin B12 for adults is 2.4 micrograms. Experts have estimated that a Western diet contains 5-7 micrograms of vitamin B12, and a multivitamin often contains 12-25 micrograms.

What happens when your vitamin b12 is low?

Weakness and fatigue are common symptoms of vitamin B12 deficiency. They occur because your body doesn't have enough vitamin B12 to make red blood cells, which transport oxygen throughout your body. As a result, you are unable to efficiently transport oxygen to your body's cells, making you feel tired and weak.

How much b12 should a man take?

The typical general supplemental dose of vitamin B12 is 1-25 mcg per day: The recommended dietary allowances (RDAs) of vitamin B12 are: 1.8 mcg; older children and adults, 2.4 mcg; pregnant women, 2.6 mcg; and breast-feeding women, 2.8 mcg.

Who will get the most benefit from a vitamin b12 supplement?

Many older adults, who do not have enough hydrochloric acid in their stomach to absorb the vitamin B12 naturally present in food. People over 50 should get most of their vitamin B12 from fortified foods or dietary supplements because, in most cases, their bodies can absorb vitamin B12 from these sources.

What is the most absorbable form of b12?

There are two forms of vitamin B12 that you're likely to come across – methylcobalamin and cyanocobalamin. Cyanocobalamin is the most commonly supplemented form of vitamin B12 and is chemically synthesised. Methylcobalamin is found in animal-based foods and is therefore obviously naturally occuring.

Does b12 help you lose weight?

Vitamin B12 for Weight Loss

B12 works by converting the food we eat into sugar and other types of fuel that keep the body running smoothly. B12 is often associated with weight loss because of its ability to boost metabolism and provide lasting energy.

Can you take vitamin D and vitamin b12 together?

Can I take Vitamin D and Vitamin B12 together? Absolutely, yes! Since these are dietary supplements, you can take them together with no worries! You can get the levels of Vitamin D and B12 in your blood checked and ask your doctor for a prescription based on their levels in your body.

Does b12 keep you awake at night?

B vitamins help regulate the body's level of tryptophan, an amino acid important for maintaining healthy sleep. Vitamin B9 (folic acid) deficiency has been linked to insomnia. Vitamin B12 (cobalamin) is reported to help insomniacs who have problems falling asleep, as well as promoting normal sleep-awake cycles.

Why does b12 make me tired?

Weakness and Fatigue

They occur because your body doesn't have enough vitamin B12 to make red blood cells, which transport oxygen throughout your body. Summary: When you are deficient in B12, your body isn't able to produce enough red blood cells to effectively transport oxygen throughout your body.

How much b12 should I take for nerve damage?

Left untreated, it can cause permanent nerve damage. Vitamin B-6 may help to maintain the covering on nerve endings. But it's important that you don't take more than 200 milligrams (mg) of B-6 per day. Taking higher amounts can lead to nerve damage and cause symptoms of neuropathy.

How do you know if your b12 is low?

Symptoms of Vitamin B12 Deficiency

Weakness, tiredness, or lightheadedness. Heart palpitations and shortness of breath. Pale skin. A smooth tongue.

When should I take b12?

Some companies also offer vitamin complexes, which are combinations of the daily amount of each B vitamin. B vitamin complex supplements are available for purchase online. Because of its energy-boosting abilities, the best time of day to take a B vitamin is after waking up.

What plant foods are high in b12?

The only reliable vegan sources of B12 are foods fortified with B12 (including some plant milks, some soy products and some breakfast cereals) and B12 supplements. Vitamin B12, whether in supplements, fortified foods, or animal products, comes from micro-organisms.

Do Almonds have vitamin b12?

While soy, almond, and rice milks are not naturally high in vitamin B12, they are usually fortified, making them an excellent source of this vitamin.

Does banana peel have b12?

Banana peels are not poisonous. In fact, they're edible, and packed with nutrients. "Banana peel is eaten in many parts of the world, though [it's] not very common in the West," Flores said. "It contains high amounts of vitamin B6 and B12, as well as magnesium and potassium.

Should seniors take b12 supplements?

Why Low Vitamin B12 Levels Are Common in Older Adults

The recommended daily allowance for vitamin B12 for adults is 2.4 micrograms. As people get older, their ability to absorb vitamin B12 tends to decrease. This is because seniors often develop problems with the acids and stomach enzymes needed to process the vitamin.

How much b12 should a senior woman take?

What's the recommended dosage of vitamin B12 for seniors? The recommended daily allowance of vitamin B12 for adults is 2.4 micrograms. Experts have estimated that a Western diet contains 5-7 micrograms of vitamin B12, and a multivitamin often contains 12-25 micrograms.

Why do older adults need b12 supplement?

B12 is important for creating red blood cells and DNA, and for maintaining healthy nerve function. “Getting enough B12 is a challenge for older people because they can't absorb it from food as well as younger people," says Tucker.

Can low b12 cause weight gain?

Why a vitamin B12 deficiency is unlikely to affect your weight. Despite the numerous processes in which vitamin B12 is involved, there's little evidence to suggest that it has any influence on weight gain or loss.

Clinical Studies

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