Vitamin B12

Cobalamin , Cyanocobalamin , Mecobalamin , Methylcobalamin

NUTRIENT FACTS

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Nutrient Type

YES

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ATC Code

No

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Deficiency Diseases

YES

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Dietary Sources

YES

Summary

  • Vitamin B12 helps make red blood cells, which carry oxygen, and supports nerve function. It’s also important for DNA synthesis, which is the process of making new genetic material. This vitamin is crucial for preventing anemia, which is a condition where the blood lacks enough healthy red blood cells, and supporting brain health.

  • Vitamin B12 is mainly found in animal-based foods like meat, fish, poultry, eggs, and dairy products. For those on a plant-based diet, fortified foods like cereals and plant-based milk can provide B12. It’s important to include B12-rich foods in your diet or consider supplements if needed, especially for vegetarians and older adults.

  • A deficiency in Vitamin B12 can lead to anemia and neurological problems like numbness or tingling in the hands and feet. Symptoms include fatigue, weakness, and memory problems. Older adults, vegetarians, and people with absorption issues are at higher risk. Addressing a deficiency is important to prevent long-term health problems.

  • Adults generally need 2.4 micrograms of Vitamin B12 per day. Pregnant women require 2.6 micrograms, while breastfeeding women need 2.8 micrograms. There is no established upper limit for B12 intake, as it is considered safe even at high doses. It’s best to meet your needs through a balanced diet or supplements if necessary.

  • Vitamin B12 supplementation is generally safe, but excessive intake can cause harm, like skin rashes or diarrhea. There is no established upper limit, but unnecessary supplementation should be avoided. It’s important to consult a healthcare provider before taking high doses, especially if you have certain health conditions, to prevent potential side effects.

Frequently Asked Questions

What does Vitamin B12 do?

Vitamin B12 is a vital vitamin that plays a key role in the body. It helps produce red blood cells, which carry oxygen throughout the body, and supports nerve function. B12 is also important for DNA synthesis, which is the process of making new genetic material. This nutrient is crucial for overall health, as it helps prevent anemia and supports brain health.

How can I get Vitamin B12 from my diet?

Vitamin B12 is mainly found in animal-based foods. Good sources include meat, fish, poultry, eggs, and dairy products. For those on a plant-based diet, fortified foods like cereals and plant-based milk can provide B12. Absorption can be affected by certain medications, digestive disorders, and age-related changes in stomach acid. It's important to include B12-rich foods in your diet or consider supplements if needed, especially for vegetarians and older adults.

How does Vitamin B12 affect my health?

Vitamin B12 deficiency can lead to serious health issues. It may cause anemia, which is a condition where the blood lacks enough healthy red blood cells, and neurological problems like numbness or tingling in the hands and feet. Symptoms include fatigue, weakness, and memory problems. Older adults, vegetarians, and people with absorption issues are at higher risk. It's important to address a deficiency to prevent long-term health problems.

Who can have low levels of Vitamin B12?

Certain groups are at higher risk for Vitamin B12 deficiency. Older adults may have absorption issues due to decreased stomach acid. Vegetarians and vegans might not get enough B12 from their diet, as it's mainly found in animal products. People with digestive disorders like Crohn's disease, which affects nutrient absorption, are also at risk. It's important for these groups to monitor their B12 levels and consider supplements if needed.

What diseases can Vitamin B12 treat?

Vitamin B12 is used to treat pernicious anemia, which is a condition where the body can't make enough healthy red blood cells due to a lack of B12. It also helps with nerve health and can be used in cases of neuropathy, which is nerve damage. B12 may support cognitive function in older adults. The evidence for these uses is strong, especially for treating anemia and neuropathy.

How do I know if I have low levels of Vitamin B12?

To diagnose a Vitamin B12 deficiency, a blood test is used to measure B12 levels. Levels below 200 picograms per milliliter indicate a deficiency. Symptoms like fatigue, weakness, and numbness may prompt testing. Additional tests, such as a complete blood count, which measures different components of blood, and methylmalonic acid levels, which can indicate B12 deficiency, help identify the cause. It's important to address deficiencies to prevent health issues.

How much supplement of Vitamin B12 should I take?

The usual daily requirement for Vitamin B12 varies by age. Adults generally need 2.4 micrograms per day. Pregnant women require 2.6 micrograms, while breastfeeding women need 2.8 micrograms. There is no established upper limit for B12 intake, as it is considered safe even at high doses. However, it's best to meet your needs through a balanced diet or supplements if necessary, especially for those at risk of deficiency.

Will supplements of Vitamin B12 interfere with my prescription medicines?

Yes, Vitamin B12 supplements can interact with certain medications. For example, they may affect the absorption of some antibiotics, like tetracyclines, which are used to treat bacterial infections. This interaction can reduce the effectiveness of the antibiotic. Additionally, Vitamin B12 can interact with medications like metformin, which is used for diabetes, potentially leading to lower Vitamin B12 levels. It's important to consult with a healthcare provider to manage these interactions effectively.

Is taking too much of Vitamin B12 harmful?

Vitamin B12 supplementation is generally safe, but excessive intake can cause harm. High doses may lead to skin rashes, diarrhea, or blood clots. There is no established upper limit for B12, but unnecessary supplementation should be avoided. It's important to consult a healthcare provider before taking high doses, especially if you have certain health conditions. Avoiding unnecessary supplements helps prevent potential side effects and interactions with medications.

What is the best supplement for Vitamin B12?

Vitamin B12 comes in several forms, including cyanocobalamin, methylcobalamin, and hydroxocobalamin. Cyanocobalamin is the most common and cost-effective form found in supplements. Methylcobalamin is more bioavailable, meaning it's easier for the body to use, and is often preferred for nerve health. Hydroxocobalamin is used in injections for severe deficiencies. Choosing a form depends on individual needs, cost, and how well the body absorbs it.

Content of Selected Foods

Food Milligrams (mg) per serving Percent DV*
Beef liver, cooked, pan fried, 3 ounces 70.7 2,944
Clams (without shells), cooked, 3 ounces 17 708
Oysters, eastern, wild, cooked, 3 ounces 14.9 621
Nutritional yeast, fortified, from several brands (check label), about ¼ cup 8.3 to 24 346 to 1000
Salmon, Atlantic, cooked, 3 ounces 2.6 108
Tuna, light, canned in water, 3 ounces 2.5 104
Beef, ground, 85% lean meat/15% fat, pan browned, 3 ounces 2.4 100
Milk, 2% milkfat, 1 cup 1.3 54
Yogurt, plain, fat free, 6-ounce container 1.0 43
Breakfast cereals, fortified with 25% of the DV for vitamin B12, 1 serving 0.6 25
Cheese, cheddar, 1½ ounces 0.5 19
Egg, whole, cooked, 1 large 0.5 19
Turkey, breast meat, roasted, 3 ounces 0.3 14
Tempeh, 1/2 cup 0.1 3
Banana, 1 medium 0.0 0
Bread, whole wheat, 1 slice 0.0 0
Strawberries, raw, halved, 1/2 cup 0.0 0
Beans, kidney, boiled, 1/2 cup 0.0 0
Spinach, boiled, drained, 1/2 cup 0.0 0
  • * DV = Daily Value. FDA developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet. The DV for vitamin B12 is 2.4 mcg for adults and children age 4 years and older [22]. FDA does not require food labels to list vitamin B12 content unless vitamin B12 has been added to the food. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet.

Required (or Advised) Daily Intake

Age Male Female Pregnant Lactating
0–6 months 0.4 0.4 - -
7–12 months 0.5 0.5 - -
1–3 years 0.9 0.9 - -
4–8 years 1.2 1.2 - -
9–13 years 1.8 1.8 - -
14+ years 2.4 2.4 2.6 2.8