From Health Facts
Cobalt is a trace mineral stored in the liver that is a component of vitamin B12. It is important in the normal development of red-blood cells. It's also involved in various enzyme reactions and aids in the formation of myelin nerve coverings.
The following foods are natural sources of cobalt. For a more expansive list on food sources of specific nutrients visit Health Canada's Dietary Reference Intakes for Elements or USDA's National Nutrient Database
- clams, oysters
- liver, kidney, meats
- dairy products
Small amounts can also be found in plant sources, and are best utilized as part of vitamin B12-rich foods.
The following are the primary uses for cobalt: 
- Anemia: Cobalt supplementation may play a role in treating anemia when other treatments don't work.
- Cancer: Cobalt in the form of radioactive cobalt-60 may treat certain kinds of cancer.
- Fatigue, digestive disorders, neuromuscular problems: Cobalt may treat these conditions.
- Recent and severe burns and injuries: Individuals with recent and severe burns and injuries may need additional amounts.
- Anorexia Nervosa and Bulimia: Individuals with anorexia nervosa and bulimia may need additional amounts.
- Vegan and Vegetarians: Many vegans and vegetarians have inadequate B12 intake and may require additional amounts of cobalt.
- weakness, especially in the arms and legs
- sore tongue
- nausea, appetite loss, weight loss
- bleeding gums
- numbness and tingling in hands and feet
- difficulty maintaining balance
- pale lips, tongue, gums
- confusion and dementia
- poor memory
In doses of 20-30mg/day, cobalt can lead to:
- enlargement of the thyroid gland (also can lead to thyroid growth in infants)
- enlargement of the heart leading to congestive heart failure
Lab tests to detect deficiency: 
- Concentrations in human plasma
- Measured in bioassay as part of vitamin B12
- The recommended dosages varies based on age and health status. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.
- Generally: Eat a balanced diet to prevent deficiency
- Pregnancy: Take as B12 if doctor advises.
- Breastfeeding: Take as B12 if doctor advises.
- Drug Interactions include:
- Colchicine - Drug may cause inaccurate lab studies of cobalt or vitamin B12.
- Neomycin - Drug may cause inaccurate lab studies of cobalt or vitamin B12.
- Para-aminosalicylic Acid - Drug may cause inaccurate lab studies of cobalt or vitamin B12.
- Phenytoin - Drug may cause inaccurate lab studies of cobalt or vitamin B12.
- Other Interactions include