With today's easy availability of dietary supplements, it is worth remembering the health impact of early
vitamin research: pellagra, scurvy, beriberi, rickets and other diseases of vitamin deficiency were virtually
eliminated overnight when widespread dietary changes were made or vitamin supplements became available.
Today in the United States, outright vitamin deficiencies are unusual, but vitamins continue to be a
fundamental focus of nutrition research. While some of their functions remain elusive, delineating vitamins'
metabolic pathways provides insights into diverse diseases. For example, common problems of the elderly
increasingly are recognized as being exacerbated by vitamin deficiencies, possibly because of poorer absorption
Ralph Green, chair of the UC Davis School of Medicine's Department of Medical Pathology, and Joshua Miller,
associate adjunct professor working with Green, are better defining the links of three B-group vitamins
to disease. These water-soluble vitamins serve as critical cofactors in a number of metabolic functions,
as well as in normal DNA synthesis.
A deficiency of vitamin B12 essential for red blood cell formation
causes anemia, as well as gastrointestinal and cardiovascular problems and "a textbook of
neurological complications," according to Green. In the U.S., the most common cause of vitamin B12
deficiency is a lack of intrinsic factor needed to absorb the vitamin from the gastrointestinal tract.
The resulting condition, "pernicious anemia," was fatal before vitamin B12
supplements became available.
In work spearheaded by Lindsay Allen, emeritus professor in the Department of Nutrition and director
of the Western Human Nutrition Research Center, Green and Miller have challenged medical dogma that pernicious
anemia occurs predominantly in northern Europeans. They've gathered epidemiological data in Latin America
and African countries, and found that not only is it at least as common in people in less-developed countries,
but it starts at younger ages.
One difficulty that has plagued clinicians and researchers is measuring an individual's ability to absorb
vitamin B12. Current methods require labeling B12 with cobalt
57 (57Co), a potentially harmful radioactive tracer. Miller and Green
are collaborating with Lawrence Livermore National Laboratory and the UC Davis Division of Biological
Sciences' Section of Microbiology to develop a better technique. The new test uses vitamin B12
labeled with carbon 14 (14C), a much safer natural isotope also used
in carbon dating. Lawrence Livermore's ultra-sensitive accelerator mass spectrometer enables them to assess
extremely small samples of body fluids, further reducing risk.
"The new assay promises to revolutionize the whole field of B12
absorption studies," says Green. They are already looking toward labeling various food sources of
vitamin B12 with 14C, and then measuring
its presence after the food is eaten by research subjects. This will provide new information on the bioavailability
of B12 in different foods, something that has been difficult to ascertain
Another prominent UC Davis nutrition researcher, Charles H. Halsted, also has a special interest in another
B vitamin more commonly known as folic acid and its role in alcoholism and alcoholic liver
Professor emeritus of internal medicine and director of the Clinical Nutrition Research Unit, Halsted
is about to launch a placebo-controlled study at the new General Clinical Research Center, which houses
clinical investigations for both the UC Davis School of Medicine and the Sacramento Veterans Affairs Medical
Center. He will evaluate the potential therapeutic effects of a nutritional supplement, S-adenosyl-methionine
(SAMe), a molecule normally produced in reactions involving folic acid, in patients with alcoholic liver
disease. His project is based on his other experimental studies that show that SAMe is lowered by alcohol
feeding and that SAMe has a positive effect in preventing the development of alcoholic liver disease.
"Alcoholism or addiction to alcohol is not a rare disease. It affects at least 5 percent
of Americans and about 1 to 2 percent of our population develops alcoholic liver disease, which is typically
fatal," Halsted says. "A dietary supplement that can prevent the progression of alcoholic liver
disease and even allow the liver to heal once the process is started could make a big difference in the
lives of many. Combined with an effective abstinence program, SAMe may give patients with alcoholic liver
disease, who were once considered hopeless, a chance for a new start."