Tips for Reducing Vitamin B12 Deficiency
Vitamin B12 deficiency in older people can be reversed by large amounts of vitamin B12 taken by mouth, according to a study in the Archives of Internal Medicine (2005;165:1167–72).
For the health of the nervous system, people require small amounts of vitamin B12 from the diet. Vitamin B12 is found in animal foods such as meats, eggs, and dairy foods, as well as small amounts in some cultured plant foods such as miso. Sufficient amounts of hydrochloric acid (HCl) and intrinsic factor (a digestive chemical) must be produced by the stomach lining to support efficient vitamin B12 absorption across the intestinal wall. Only about 1% of the vitamin B12 taken by mouth will be absorbed in people who don’t produce enough of either HCl or intrinsic factor. These people, often the elderly, are especially susceptible to vitamin B12 deficiency.
Symptoms of vitamin B12 deficiency include fatigue, lethargy, anemia, depression, and neuropathy (numbness, tingling, twitching, and other forms of nerve dysfunction). Intramuscular injections are generally used to treat a deficiency that is caused by malabsorption of vitamin B12, although previous research has found that supplementing with high amounts of oral vitamin B12 can also be effective. The exact amount of oral vitamin B12 needed to reverse a deficiency, however, is not known.
The 120 participants in the current study were at least 70 years old and had low levels of vitamin B12 and high levels of methylmalonic acid (a chemical that increases in concentration in association with vitamin B12 deficiency) in their blood. They were randomly assigned to receive either 2.5, 100, 250, 500, or 1,000 mcg of oral vitamin B12 per day for 16 weeks. Blood levels of vitamin B12 and methylmalonic acid were measured at the beginning of the study and after 8 and 16 weeks of treatment. Vitamin B12 levels rose and methylmalonic acid levels dropped in all groups by the eighth week of treatment and were stable for the last 8 weeks of the study. The average drop in methylmalonic acid levels was 16% in those taking 2.5 and 100 mcg, 23% in those taking 250 mcg, and 33% in those receiving 500 and 1,000 mcg per day. Approximately 76% of the people taking the highest amount had normal levels of methylmalonic acid by the end of the study, compared with only 21% of the people taking the lowest amount. From these numbers, it was calculated that between 647 and 1,032 mcg of oral vitamin B12 per day is needed to reverse vitamin B12 deficiency.
It is noteworthy that the amount needed to reverse deficiency in this study is at least 215 times greater than the recommended dietary allowance of 3 mcg per day. While much lower amounts of supplemental vitamin B12 can restore low blood levels of the vitamin to normal, some researchers have argued that methylmalonic acid levels are a more reliable indicator of vitamin B12 status in the body. Consequently, relatively large amounts of the vitamin appear to be necessary to achieve optimal vitamin B12 status in elderly, vitamin B12–deficient people. Vitamin B12 supplements are safe and inexpensive; therefore, a daily amount of 1,000 mcg may be advisable for people with vitamin B12 deficiency. People who have vitamin B12 deficiency because of pernicious anemia (a gastrointestinal disorder that leads to vitamin B12 malabsorption) should consult a doctor to determine whether they should receive oral or injectable vitamin B12.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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