Summary
Highlights
The recommended daily allowance for adults is 2.4 micrograms. B12 is abundant in animal products like fish, meat, poultry, eggs, and dairy. Fortified foods include certain breakfast cereals and nutritional yeast. Examples of B12 content: a 6-ounce plain yogurt has 1 microgram (43% daily intake), a large egg 0.5 micrograms (19% daily intake), and nutritional yeast contains 8.3-24 micrograms (346-1000% daily intake).
Certain medications can increase the risk of B12 deficiency. Proton pump inhibitors (PPIs) like pantoprazole and omeprazole reduce stomach acid, impairing the release of protein-bound B12. Metformin, commonly prescribed for pre-diabetes and type 2 diabetes, also reduces B12 absorption. Patients on these medications should discuss their B12 levels with their healthcare provider.
B12 deficiency is typically treated with injectable formulations to bypass digestive absorption barriers. Oral B12 supplements or B complex vitamins can provide energy and may disrupt sleep if taken in the evening; it's recommended to take them in the morning. While nutritional needs should ideally be met through food, supplementation or fortified foods are necessary in certain cases to maintain adequate B12 levels.
Natural B12 in food is protein-bound and needs to be released. This process begins in the mouth with saliva, continues in the stomach with hydrochloric acid and gastric enzymes, and in the intestines, intrinsic factor helps release and transport B12. This absorption process is simpler for B12 in supplements or fortified foods as it's not protein-bound, aiding absorption for those with compromised digestive processes.
B12 deficiency is rare under 60 (up to 6% of the population) but rises to 20% in those over 50. Symptoms include paleness, weakness, low energy, hair loss, megaloblastic anemia (large, abnormal red blood cells), glossitis of the tongue, and neurological symptoms like numbness and tingling in hands and feet, which can occur even without anemia. The body stores a large amount of B12 (1000-2000 times daily intake), so deficiency symptoms may take a long time to appear.
Individuals at higher risk include vegetarians and vegans who don't consume animal products, people with pernicious anemia (an autoimmune condition affecting intrinsic factor production), those with intestinal surgeries or digestive issues like Crohn's or Celiac disease, and older adults. Age is a significant factor as stomach acid and enzyme production decrease, making it harder to break down protein-bound B12.
Vitamin B12, or cobalamin, is one of the eight B vitamins. It's water-soluble and crucial for DNA synthesis, fatty acid, and amino acid metabolism. It's found naturally in some foods, added to others (fortified foods), and available as supplements or injectables for those with absorption issues. B12 contains cobalt, vital for healthy red blood cell development and a healthy nervous system.