Cobalamin or Vitamin B12 and folate or vitamin B9 are both needed for DNA synthesis and repair. B12 is also involved in fatty acid synthesis and energy utilization. These vitamins are important for development as well, and deficiency is linked to a number of diseases. In addition to deficiency, the toxicity has been studied, as well as interactions with diseases and medications. It is important to consult a health care professional regarding dietary management and the diagnosis and treatment of disease.
Folate Health Risks
According to the Office of Dietary Supplements, the risk of toxicity from folate is quite low. In part this is because it is a water soluble vitamin, so it can be excreted in the urine as excessive amounts are consumed. The upper limit of folate intake is 1,000 micrograms, equal to 1 mg, in persons age 19 and older. If more folate is consumed, it can cause worse symptoms from a B12 deficiency. This is because B12 deficiency is diagnosed by the combination of anemia, or low blood cell counts with large cells called megaloblastic anemia, and nerve problems. The folate corrects the anemia and does not correct the nerve problems, making the diagnosis more difficult.
Folate Medical Interactions
Folate may provoke seizures in persons prone to seizures who are taking anticonvulsant medications. It may also interact with some cancer drugs; this should be discussed with a health care professional.
Vitamin B12 Health Risks
According to a 2006 article by Dr. E. Lonn in the "New England Journal of Medicine" vitamin B12 has an extremely low toxicity. Like folate, it is water soluble, and excessive amounts are lost in the urine. The treatment of megaloblastic anemia with high doses of B12 can cause low blood potassium which can be fatal. It can also cause low platelets.
Vitamin B12 Medical Interactions
High doses of vitamin B12 should not be given to people with a rare hereditary disease of the visual system called Leber's disease because it can cause blindness. In addition if a person has a blood growth disorder called polycythemia vera and a B12 deficiency, the disease will be masked. If B12 is given, the disease will be unmasked, and complications such as blood clots can occur.
References
- National Institutes of Health: Office of Dietary Supplements: Folate
- "Harrison's Principles of Internal Medicine, 17th Ed."; Anthony S Fauci et al; 2008
- "New England Journal of Medicine"; "Homocysteine lowering with folic acid and B vitamins in vascular disease"; Lonn et al; 2006
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