Vitamin D May Prevent Arthritis

Research Links Vitamin D Deficiency to Rheumatoid Arthritis

By Salynn Boyles
WebMD Medical News   Reviewed By Brunilda  Nazario, MD
on Friday, January 09, 2004  

Jan. 9, 2004 -- Move over vitamins A, B, C and E. It is beginning to look like
the long ignored vitamin D is every bit as important for preventing disease as
you are.

New research makes the case that vitamin D helps protect older women against
rheumatoid arthritis -- an autoimmune joint disorder of unknown cause. Recent
studies have also linked deficiencies of vitamin D to other disorders such as
certain cancers, heart disease, diabetes, and even unexplained pain but its
role in human autoimmune disease is less clear.

The studies are far from conclusive, but researcher Michael Holick, MD, says
there is every reason to believe that the supplement plays a much bigger role
in disease prevention than has been recognized.

"Vitamin D has always been considered sort of a ho-hum vitamin," Holick tells
WebMD. "People think they get plenty of it from the sun or in their diets, but
these days that just isn't the case."

Vitamin D and Rheumatoid Arthritis

The latest research drew on data from the Iowa Women's Health Study, which
followed almost 30,000 women, aged 55 to 69, for 11 years. Over the course of
the study, the women were questioned about their eating habits, their use of
nutritional supplements, and other health-related issues.

During the trial, 152 of the women developed rheumatoid arthritis. The
investigators found that women whose diets were highest in vitamin D had the
lowest incidence of rheumatoid arthritis.

Women who got less than 200 international units (IU) of vitamin D in their
diets each day were 33% more likely to develop rheumatoid arthritis than women
who got more, researcher Kenneth G. Saag, MD, tells WebMD. Saag is an associate
professor of medicine at the University of Alabama at Birmingham.

The association remained significant even after the researchers adjusted for
other suspected rheumatoid arthritis risk factors, such as smoking. And even
though many foods with vitamin D are also high in calcium, the vitamin's
protective effect seemed to be independent of how much calcium the women ate.

The findings are reported in the January 2004 issue of the journal Arthritis
and Rheumatism.

How Much Is Enough?

An 8-ounce glass of milk or fortified orange juice has about 100 international
units (IU) of vitamin D and a typical multivitamin has 200 to 400 IU. Other
good dietary sources of vitamin D include cod liver oil, which has 1360 IU of
vitamin D per tablespoon; salmon, which has 425 IU per 3-ounce serving; and
herring and sardines. The recommended intake of adequate amounts of vitamin D
depends on a person's age. The Food and Nutrition Board (FNB) of the Institute
of Medicine says that older women should consume 400 to 600 IU per day in order
to have adequate vitamin D intakes.

Like Holick, Saag says he believes vitamin D deficiency is an under-recognized
health problem in the U.S. today.

"General population studies indicate that about one in three people are vitamin
D deficient," he says. "This is a particular problem during the winter months,
when sun exposure is minimal. This is another reason why people should think
about supplementing their diets with a multivitamin."

But Holick says most people need to take 1000 IU of vitamin D each day. And he
says even this amount may be inadequate in people who have no exposure to the
sun.

"Most people get between 90% and 95% of their vitamin D from sun exposure, so
if you eliminate that you are setting the entire country up for vitamin D
deficiency," he says.

The director of the Vitamin D Research Lab at Boston University, Holick
advocates a limited amount of sun exposure, without sunscreen, every day -- a
message that the nation's top dermatology group abhors. In a recent press
release, officials with the American Academy of Dermatology expressed "deep
concern" that the public is being misled "about the very real danger of
[unexposed] sun exposure -- the leading cause of skin cancer."

But Holick counters that it does not take much sun to get more than enough
vitamin D -- only a few minutes of unprotected sun exposure at most for most
people.

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SOURCES: Saag, K. Arthritis and Rheumatism, January 2004; vol. 50: pp. 72-77.
Kenneth G. Saag, MD, MSc, associate professor, division of clinical immunology
and rheumatology, University of Alabama, Birmingham. Birmingham. Michael
Holick, MD, Vitamin D Research Lab, department of medicine, Boston University
Medical Center.

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