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High doses of supplemental vitamin B12 needed to correct deficiency
The May 23 2005 issue of the American Medical Association journal Archives of Internal Medicine (http://archinte.ama-assn.org/) published the findings of Dutch researchers that much higher levels of vitamin B12 are needed to remedy a deficiency of the vitamin than are provided by the Netherlands’ recommended dietary allowance of approximately 3 micrograms per day. (In the US, the daily value for vitamin B12 is 6 mcg, however, the Institute of Medicine’s dietary reference intake is lower at 2.4 mcg per day.) A common means of correcting vitamin B12 deficiency is intramuscular injection of the vitamin, however, oral vitamin B12 has also been shown to be effective, although an optimal dose has not been determined.
Daily oral doses of 2.5, 100, 250, 500 and 1000 micrograms cyanocobalamin were administered for 16 weeks to 120 people aged 70 and older with vitamin B12 deficiency determined by low serum B12 and elevated plasma methylmalonic acid (MMA). Methylmalonic acid is a compound that is produced in the body when vitamin B12 is insufficient. Vitamin B12 is additionally needed to remethylate homocysteine to the amino acid methionine, therefore elevated total homocysteine can also be an indicator of B12 deficiency.
The participants’ blood samples were analyzed for cobalamin and MMA at 8 and 16 weeks. Plasma MMA was reduced in all participants at 8 weeks and remained stable through the study’s conclusion. Greater mean reductions in MMA were observed with increasing doses of vitamin B12, however, the highest dose of 1000 micrograms cyanocobalamin lowered MMA by the same percentage (33%) as 500 micrograms. Analysis of the data determined that the lowest dose resulting in 80 to 90 percent of the maximum reduction in MMA varied from 647 to 1032 micrograms per day.
The authors conclude that “the lowest dose of oral cyanocobalamin required to normalize biochemical markers of mild vitamin B12 deficiency in older people with a mild vitamin B12 deficiency is more than 200 times greater than the recommended dietary allowance for vitamin B12 of approximately 3 micrograms per day. Clinical trials are currently assessing the effects of high doses of oral cobalamin on markers of cognitive function and depression . . . However, the present trial demonstrates that much higher doses of cyanocobalamin are required to normalize vitamin B12 deficiency than were previously believed.”
Recent studies show that people with dementia of the Alzheimer's type have elevated levels of homocysteine in their blood. At an international scientific conference held in The Netherlands the week of April 27, 1998 , a team of scientists unveiled findings showing a definitive link between elevated homocysteine and Alzheimer's disease.
Research reported at Tufts University in 1995 documented the same finding linking elevated homocysteine and Alzheimer's disease and recommended supplementation with folic acid and vitamin B12. It should be noted that dementia can be caused by a deficiency of vitamin B12, folic acid, and other nutrients, so another reason people with dementia of the Alzheimer's type have elevated homocysteine levels could be that they are suffering from a common vitamin deficiency. Numerous studies conducted on the elderly show that deficiencies of folic acid, vitamin B12, and other nutrients are epidemic in elderly people who do not take vitamin supplements. Since both elevated homocysteine and vitamin deficiencies have been linked to dementia, the best approach to preventing and treating dementia (including Alzheimer's dementia) would appear to be testing the blood for elevated homocysteine and taking methylation enhancing nutrients such as folic acid, TMG, and vitamin B12.
Measuring blood levels of homocysteine is a new and potentially life-saving test that provides information about vitamin and methylation status, in addition to determining levels of toxic homocysteine. Those with a family history of heart disease, stroke, or Alzheimer's disease are at a particular risk for elevated homocysteine. Elevated homocysteine has also been linked to complications in diabetes, lupus, and other chronic diseases. While many people have assumed that because they are taking vitamin supplements, their homocysteine levels will be in a safe range, The Life Extension Foundation has discovered that this might not always be the case.
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This year’s theme is “Exploring New Pathways – Sharing the Journey,” and will focus many of the lecture discussions on the “new pathways” for diagnosing, staging and treating prostate cancer.
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Prostate Cancer patients and survivors.
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