Functions
- Red blood cell formation
- Involved in synthesis of nucleic acids
- Fatty acid catabolism
- Nervous system myelination (covering over nerves)
- Reduction of glutathione
Deficiency
- Pernicious anemia
- Unsteady gait and dizziness
- Chronic fatigue or drowsiness
- Constipation
- Depression, Irritability, or mood swings
- Digestive disturbances
- Liver enlargement
- Hallucinations
- Headaches
- Nerve disorders
- Spinal cord degeneration
- Inflammation of tongue
- Palpitations
- Tinnitus
Characteristics
- soluble in water or alcohol
- unstable in hot alkaline or acid solutions
Good Sources
Natural
- beef, pork, chicken
- liver, kidney
- milk and dairy products
- eggs
- clams, oysters, king crab, herring, salmon, tuna
- most of vitamin required by humans is synthesized by intestinal bacteria
| Food | Quantity | mcg |
|---|---|---|
| Beef, lean braised flank | 3 oz | 2.81 |
| Chicken | 1/2 breast | 0.29 |
| Milk, non-fat | 1 cup | 0.93 |
| Egg | 1 large | 0.50 |
Artificial
- fortified cereals and soy products
Recommended Daily Allowances (RDA)
- Males (11 yrs. and older)
- 2.4 mcg
- 3 mcg
- Females (11 yrs. and older)
- 2.4 mcg
- 3 mcg
- Pregnant females
- 4 mcg
- Lactating females
- 5 mcg
- Children
- 2-5 mcg
- Infants
- 1-2 mcg
- Varied values reflect different references
Tolerable Upper Intake Levels (UL)
- Adults (19 to 50 yrs)
- not yet determined
- Generally considered non-toxic
- Intakes above UL may lead to negative health consequences
- Eg: Oversupply of B-12 works against Vitamin C concentrations in tissues
Supplementation
- Not usually necessary
- People who are on strict vegetarian diets may need supplementation.
- some recommend 25-500 mcg daily
- Some elderly people and those with certain food intolerances may be deficient in Vitamin B-12 because they lose their ability to absorb B-12 from foods.
- In which case, parenteral vitamin B-12 can be prescribed by a health care professional.
- Not required to be taken with other nutrients
