New technique for measuring vitamin B12 components.

A new way to measure quantities of vitamin B12, both in foods and in dietary supplements, has been developed by USDA-ARS scientists. As we all know, Vitamin B12 is an essential nutrient linked to human growth and cell development. The Food and Nutrition Board of the Institute of Medicine, which establishes reference values for nutrient intakes, advocates research related to absorption and bioavailability of this important nutrient.

Scientifically, vitamin B12 is one in a family of compounds called cobalamins. Each form has its own potential biological activity in terms of absorption and potency. Naturally occurring forms of B12 are found predominantly in meat and dairy products. A synthetic form, cyanocobalamin, is used in the United States to fortify foods and to make dietary supplements.

A microbiological assay has commonly been used to analyze the amount of B12 in samples, but that method takes days and is expensive. Another drawback is that it measures the total amount of B12 in a sample, but not how much of each of the individual forms of the vitamin.

The newer technique for quantifying cobalamins uses one of two separation methods. One is capillary electrophoresis, or CE, and the other is micro-high-performance liquid chromatography, or HPLC. Capillary electrophoresis is combined with a detection technique called inductively coupled plasma mass spectrometry, or ICP-MS.

This hybrid approach allows scientists to quickly detect and measure levels of specific cobalamins, according to research chemists. ARS scientists are testing various food and supplement samples using CE-ICP-MS to measure the various cobalamins. Preliminary results indicate important data findings in commercial vitamin supplements. Future projects will focus on human breast milk.

Accuracy in measuring the quantity of each of the cobalamins in foods and supplements is crucial for understanding absorption mechanisms, which will lead to health recommendations important to the public. About 10% to 15% of adults more than 60 years of age are affected by a vitamin B12 (cobalamin) deficiency. The deficiency is usually only discovered when patients develop megaloblastic anemia. However, before this stage is reached, cobalamin-deficient individuals may develop neuropsychiatric damage and show signs of disorientation and confusion, according to researchers at Columbia University, New York, NY.

Further information. Nancy Miller-Ihli, Food Composition Laboratory, USDA-ARS Beltsville Human Nutrition Research Center, 10300 Baltimore Blvd., Building 161, Room 001, BARC-East, Beltsville, MD 20705; phone: [phone]; fax: [phone]; email: [e-mail].