The researchers looked at nearly 30,000 women from the Iowa Women's Health
Study. All had answered a food questionnaire in 1986 that assessed how much and
how often they ate certain foods as well as their vitamin and supplement intake.
Years later, there were 158 cases of rheumatoid arthritis among the women.
The diets of those women were compared with those of study participants who
remained free of the illness.
The doctors found that women getting less than 40 micrograms of
beta-cryptoxanthin, which is found in citrus fruits like oranges and grapefruit,
were at a slightly higher risk of developing rheumatoid arthritis than women who
consumed more than that amount.
When they looked at the amount of zinc in each woman's diet, they found that
those who took zinc supplements had a lower risk of rheumatoid arthritis. But
getting an equivalent amount of zinc from food was not associated with decreased
risk.
Their results are published in the February issue of the American Journal of
Epidemiology.
Dr. James Cerhan of the Mayo Clinic in Rochester, Minnesota, one of the
study's authors, told Reuters Health that the findings must "be replicated
before we go out and tell the public to take zinc and eat oranges."
However, he says the study's strength was its ability to look at women's
diets before they developed arthritis. He says people with rheumatoid arthritis
often change their diets after getting a diagnosis in the hopes that certain
foods will improve their symptoms.
But the only well-defined risk factor for rheumatoid arthritis is genetics,
according to Cerhan. The disease is caused by a misguided immune system attack
on the body's own joint tissue, which leads to swelling, pain, stiffness and in
some cases deformity. Rheumatoid arthritis is more common among women than men.
Cerhan says the results are "interesting, but we can't take this as the
definitive study."
The message to the general consumer, he adds, is "here's another reason to
eat your fruits and vegetables.
"Not only can they protect you from chronic diseases such as cancer and heart
disease, but now they may also prevent rheumatoid arthritis."
