Vitamin B12
What is Vitamin B12?
Definition
Vitamin B12, also known as cobalamin, is a water-soluble vitamin that plays a crucial role in various bodily functions. It is essential for the production of red blood cells, DNA synthesis, and proper nerve function. Vitamin B12 is not produced by the body and must be obtained from food or supplements.
Sources
Vitamin B12 is naturally found in animal products such as meat, fish, poultry, eggs, and dairy products. Some fortified plant-based foods, such as breakfast cereals and nutritional yeast, also contain Vitamin B12.
Recommended Daily Intake
The recommended daily intake of Vitamin B12 varies depending on age, sex, and life stage. For adults, the recommended intake is 2.4 micrograms (mcg) per day (1). Pregnant and lactating women may require higher amounts.
Deficiency
Vitamin B12 deficiency can lead to anemia, fatigue, weakness, constipation, loss of appetite, and neurological problems. Vegans, older adults, and people with certain medical conditions that affect nutrient absorption are at a higher risk of deficiency.
Supplementation
Vitamin B12 supplements are available in various forms, including tablets, capsules, and injections. People who follow a vegan or vegetarian diet, older adults, and those with absorption issues may benefit from B12 supplementation. It is recommended to consult a healthcare provider before starting any supplementation.
Interactions with Medications
Vitamin B12 supplements may interact with certain medications, such as metformin, proton pump inhibitors (PPIs), and histamine H2 receptor antagonists. These medications can interfere with B12 absorption or increase the risk of B12 deficiency. It is essential to talk to a healthcare provider if you are taking any of these medications and considering B12 supplementation.
Health Risks from Excessive Intake
There is no known toxicity associated with high Vitamin B12 intake from food or supplements. The body excretes any excess B12 through urine. Therefore, there is no established tolerable upper intake level (UL) for Vitamin B12 (1).
Time of Day and With or Without Food
There is no specific time of day to take Vitamin B12 supplements. It can be taken with or without food, depending on personal preference.
Dosage
The most common form of Vitamin B12 in dietary supplements is cyanocobalamin (1). The dosage of Vitamin B12 supplements varies depending on the individual's age, sex, and life stage. For adults, the recommended dose is 2.4 mcg per day (1). In cases of Vitamin B12 deficiency, higher doses may be required, and injections may be necessary.
Side Effects
Vitamin B12 supplements are generally considered safe and have no known side effects when taken in recommended doses (1). However, high doses of Vitamin B12 supplements may cause acne, rosacea, and other skin problems (1).
Citations:
(1) ODS Vitamin B12 Fact Sheet for Health Professionals
(2) Harvard T.H. Chan School of Public Health: Vitamin B12
(3) NHS Inform: Vitamin B12 or Folate Deficiency Anaemia
(4) NCBI Bookshelf: Vitamin B12
(5) Mayo Clinic: Vitamin B12
(6) Mount Sinai: Vitamin B1 Thiamine