Nutrient Information: Vitamin B12

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Nutrient Key Information
Nutrient Name:	Vitamin B12
Nutrient Category:	Vitamins and Other Components
Measuring Unit:	µg
Nutrient Summary:	Vitamin B12 is essential for normal blood formation and body neurological function.
Nutrient Function:	Help red blood cell formation and prevent anemia Play the role in nerve cells growth and the nervous system function. It may play a role in preventing brain atrophy which often associated with memory loss or dementia. Vitamin B12 and folate together to help DNA and RNA synthesis of new cells Conversion of food into energy by metabolism of certain fatty acids and amino acids. Vitamin B12 and folate depend on each other for their activation. Vitamin B12 removes a methyl group CH3 from folate and attaches it to itself to activate both Vitamin B12 and folate. Vitamin B₁₂ is processed in the stomach and the small intestine, and then released into the circulation. To absorb vitamin B₁₂ from foods, there are two steps (vitamin B₁₂ absorption from supplements only needs step #2): 1) Hydrochloric acid and the digestive enzyme pepsin in the stomach separates vitamin B₁₂ from the protein that it's attached to. 2) Then the freed vitamin B₁₂ combines with a protein secreted by the stomach, called intrinsic factor. Now the small intestine's receptors can recognize and absorb the Vitamin B₁₂. Some people cannot absorb Vitamin B₁₂ well: 1) People older than 50 years old who produce less hydrochloric acid in their stomach. 2) People who eat little or no animal foods. 3) People with autoimmune diseases who cannot produce enough hydrochloric acid and/or intrinsic factor. 4) People with stomach or intestinal surgery who cannot produce enough hydrochloric acid and/or intrinsic factor. 5) People who take some medication which suppresses gastric acid production. In the body, vitamin B₁₂ is circulated via bile and delivered back to the intestine where it is reabsorbed.

Vitamin B12 Chemistry Structure

Vitamin B12 Rich Foods

Food Sources

Foods naturally containing vitamin B₁₂ are primarily animal origin foods. Milk and fish have the greatest B₁₂ bioavailability.

• Fish, such as mackerel, herring, sardines, tuna, trout, salmon
• Dairy products, such as milk (cautious: boiling milk will significantly reduce the Vitamin B₁₂ content)
• Shellfish, such as clams and oyster
• Organ meats, such as beef liver
• Eggs
• Meat, such as beef, pork
• Poultry, such as turkey, chicken drumstick
• Fortified cereals

Attention for vegan diet (pure vegetarian): plant foods have no vitamin B₁₂ unless they are fortified, such as fortified ready-to-eat cereals and meal replacement formulas.

Note:
1. 10–30% of people older than 50 years old may be unable to absorb naturally occurring vitamin B₁₂ because of the lower stomach acid secretion caused by the atrophic gastritis. Experts advise people older than 50 to consume foods fortified with vitamin B₁₂ or take Vitamin B₁₂ supplements to meet their daily Vitamin B₁₂ needs.
2. Vitamin B₁₂ can be destroyed by microwave cooking

Sample Foods High in: Vitamin B12 View Additional Food Sources
	Food Description	Nutrient Amount¹	Daily Value%²
	Mollusks, clam, mixed species, cooked, moist heat Category: Finfish and Shellfish Products Similar foods: cooked clam	98.89 µg	4,120.42%
	Beef, variety meats and by-products, liver, cooked, pan-fried Category: Beef Products Similar foods: cooked beef liver	83.13 µg	3,463.75%
	Mollusks, oyster, Pacific, cooked, moist heat Category: Finfish and Shellfish Products Similar foods: oyster	28.8 µg	1,200.00%
	Fish, mackerel, Atlantic, cooked, dry heat Category: Finfish and Shellfish Products Similar foods: mackerel fish	19 µg	791.67%
	Fish, tuna, fresh, bluefin, cooked, dry heat Category: Finfish and Shellfish Products Similar foods: cooked tuna fish	10.88 µg	453.33%
	Milk, reduced fat, fluid, 2% milkfat, with added vitamin A and vitamin D Category: Dairy and Egg Products Similar foods: 2% milk	0.55 µg	22.92%
	Beef, plate steak, boneless, outside skirt, separable lean and fat, trimmed to 0" fat, all grades, cooked, grilled Category: Beef Products Similar foods: cooked beef plate skirt	7.72 µg	321.67%
	Turkey, retail parts, drumstick, meat only, cooked, roasted Category: Poultry Products	2.53 µg	105.42%

¹ Nutrient amount is in 100 gram food
² Use FDA 2000 calorie diet as Daily Value reference

Additional Nutrient Information
Nutrient Summary	Vitamin B12 is essential for normal blood formation and body neurological function.
Deficiency Health Effects	Usually vitamin B₁₂ deficiencies are caused by lack of hydrochloric acid (releasing vitamin B₁₂ from foods) or lack of intrinsic factor (enabling vitamin B₁₂ absorption) in the stomach. The common symptom of vitamin B₁₂ deficiency is fatigue or lack of energy. The main problems vitamin B12 deficiency can cause are: Hematological effects: megaloblastic anemia or pernicious anemia. Symptoms include weakness, fatigue, dizziness, shortness of breath, and heart palpitations. When anemia is established, some degree of neutropenia and thrombocytopenia may occur that may increase the risk of infection. Neurological effects: Neurological complications are present in 75–90% of individuals with vitamin B12 deficiency. Symptoms include tingling and numbness in the fingers or toes, tremors or uncontrollable shaking for some people, gait disturbances, loss of concentration, memory loss, disorientation, dementia, visual disturbances, depression and insomnia. Even marginal vitamin B₁₂ deficiency impairs memory and cognition. Gastrointestinal effects: Vitamin B12 deficiency is often associated with gastrointestinal complaints, such as loss of appetite, flatulence, and constipation. Note: Excessive folate intake from supplement may obscure the vitamin B12 deficiency that can result in unrecognized neurological damage.
Effects if Above Upper Limit	Due to inadequate data on adverse effects of excess vitamin B12 consumption, a Upper Limit for the vitamin B₁₂ could not be determined. No adverse effects have been associated with excess vitamin B₁₂ intake from food or supplements in healthy individuals. Apparently only a small percentage of vitamin B₁₂ can be absorbed from the gastrointestinal tract.
External References	The National Academies of Science, Engineering, Medicine publication: Dietary Reference Intakes healthline.com Article: 9 Health Benefits of Vitamin B12, Based on Science NIH (National Institutes of Health) article: Vitamin B12 Nutrition Science Book: Understanding Nutrition by Ellie Whitney and Sharon Rady Rolfes

Daily Value Age Group	Recommended Daily Values
Toddler 1 to 3 years old:	0.9 µg
Child 4 to 8 years old:	1.2 µg
Male 9 to 13 years old:	1.8 µg
Male 14 to 18 years old:	2.4 µg
Male 19 to 30 years old:	2.4 µg
Male 31 to 50 years old:	2.4 µg
Male 51 to 70 years old:	2.4 µg
Male Senior 71 or older:	2.4 µg
Female 9 to 13 years old:	1.8 µg
Female 14 to 18 years old:	2.4 µg
Female 19 to 30 years old:	2.4 µg
Female 31 to 50 years old:	2.4 µg
Female 51 to 70 years old:	2.4 µg
Female Senior 71 or older:	2.4 µg
Female Pregnancy (>18):	2.6 µg
Female Lactation (>18):	2.8 µg
FDA (Based on 2000 calorie daily diet):	2.4 µg

	The nutrient Dietary Reference Intakes and nutrition facts is from Institute of Medicine of National Academies 2006. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press. https://doi.org/10.17226/11537
	Nutrition facts knowledge are based on U.S. FOOD & DRUG Administration Nutrition Education Resources & Materials. https://www.accessdata.fda.gov/scripts/interactivenutritionfactslabel/
	Nutrition facts knowledge are based on National Institutes of Health Dietary Supplement Fact Sheets. https://ods.od.nih.gov/factsheets/list-all
Disclaimer	The nutrient information provided here should not take the place of medical advice. We encourage you to talk to your healthcare providers (such as your doctor) about your dietary requirements which are best for your overall health. We also recommend you to read organization or professional reference documents or articles mentioned, but not limited to, in this page. Any mentions and reference links in this page don't represent our endorsement of their services and advice.

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