Vitamin B12 is used in every cell in the body. It is a cofactor involved in DNA synthesis, amino acid metabolism, and fatty acid metabolism. It is particularly important in creating myelin sheath, which coats and protects nerve cells. It is important for red blood cell creation, immune function, psychological and neurological function, and heart health. It also helps cells metabolize proteins, carbs, and fats, may help prevent cardiovascular disease, may prevent brain atrophy related to Alzheimer’s disease and other mental decline associated with age. Sources include liver, seafoods like clams, crab, and tuna, beef, dairy, cod, halibut, herring, mackerel, salmon, snapper, and trout.
Quick Facts
-Only found in animal foods
-Used in every cell of the body
-A cofactor involved in DNA synthesis, amino acid metabolism, and fatty acid metabolism
-Particularly important in creating myelin sheath, which coats and protects nerve cells
-Unique because it contains a metal ion of the element Cobalt
-Large range of bioavailability: eggs ~9%, meats 40 – 60%
-Important for red blood cell creation, immune function, psychological and neurological function, and heart health
[55][56]
-Helps cells metabolize proteins, carbs, and fats, may help prevent cardiovascular disease, may prevent brain atrophy related to Alzheimer’s disease and other mental decline associated with age, when taken with fish oil it may reduce triglycerides and cholesterol [160]
RDI
Males 19 – 30 yrs: 2.4 μg
Females 19 – 30 yrs: 2.4 μg
[128]
Deficiency
-Dangerous anemia indicated by fatigue, weakness, diarrhea, weight loss, pale skin, sore red tongue or mouth, hypotension, loss of appetite, unsteady movement, heart palpitations, confusion, disorientation or hallucinations, irritability, depression or other mood disturbance, memory loss or dementia, association with Alzheimer’s, dandruff, vision problems, high blood levels of homocysteine, which increases risk of heart attack and strokes, association with breast cancer, slowed growth, movement disorders, anemia in infants [160]
Toxicity
-No upper limit exists because it is water soluble and excess can be flushed out in the urine
-Supplementing with very high levels of B12 have shown negative side effects. Megadoses can cause acne and rosacea, though these studies use injections rather than oral supplements.
-Can cause kidney function to decline in those with diabetes or kidney disease [172]
Sources
Liver, seafoods like clams, crab, and tuna, beef, dairy [55][56], cod, halibut, herring, mackerel, salmon, snapper, trout [160]
