But a few years later, a private pharmaceutical firm began
taking a good, long look at 1,24-dihydroxyvitamin D2 for
potential benefits to human health.
Various independent studies have suggested that vitamin
D can treat or prevent cancer. "It prevents growth of cancer cells,"
says Horst. But its toxicity hampered this research.
Excessive intake of vitamin D can lead to anorexia, nausea,
vomiting, weakness, nervousness, and impaired renal function, as well
as calcification of blood vessels and kidneys. That is why 1,24-dihydroxyvitamin
D2 was attractive to researchers.
"It has a good safety profile," says Joyce Knutson,
director of preclinical research at Bone Care International, Inc., based
in Madison, Wisconsin. "When you are using a form of vitamin D
to fight cancer, you don't want its elevating effect on calcium to create
She says LR-103, which is 1,24-dihydroxyvitamin D2's
pharmaceutical name, will enter clinical trials for its effect on a
variety of cancers before year's end. Bone Care and ARS share a patent
on the drug.
...And It Tenderizes Meat
Vitamin D's toxicity was used in a positive way in studies conducted
with Iowa State University in Ames, which were led by Donald Beitz,
a professor of animal science and biochemistry. This research is now
being evaluated within the U.S. beef industry.
"We took advantage of the potential toxic effect of vitamin D,
and of vitamin D3 in particular," says Horst. The result:
a new way to tenderize beef.
Horst explains that if animals receive too much vitamin D, their blood
calcium levels can rise to 40 to 50 percent above normal. "If blood
calcium remains at these concentrations for several days, animals can
become sick and eventually die," he says. "But most mammals
can tolerate an increase in blood calcium of 20 to 30 percent for 3
to 5 days without any harm.
"Creating that 20- to 30-percent elevation in blood calcium by
feeding excess vitamin D3 2 to 3 days before slaughter results
in greater muscle calcium and more tender cuts of meat," he says.
"Elevated calcium in the meat activates postmortem muscle enzymes
that can help degrade structural proteins responsible for tough meat."
He says the method triggers no ill effect for consumers and has no
harmful effect on the animal, unless too much vitamin D3
is used. ARS and Iowa State University share a patent on this technique,
which is being tested by private firms. Interest has increased in the
past 2 years.
An identical method has been applied to pork. It has led to improved
meat color, but no tenderizing effect has been observed.By Luis
Pons, Agricultural Research Service Information Staff.
This research is part of Animal Health, an ARS National Program
(#103) described on the World Wide Web at www.nps.ars.usda.gov.
Ronald L. Horst is
with the USDA-ARS U.S. National
Animal Disease Center, 2300 Dayton Ave., Ames, IA 50010-0070; phone
(515) 663-7312, fax (515) 663-7669.
"Vitamin D Research: Humans May Benefit From Animal Health
Studies" was published in the July
2003 issue of Agricultural Research magazine.