Vitamin C: A possible treatment for high blood
December 20, 1999
Web posted at: 10:10 a.m. EST (1510 GMT)
By Sarah Yang
(WebMD) -- Vitamin C has been touted as a treatment
for the common cold, gallbladder disease and blocked
arteries. Too little in the diet can cause scurvy, a
disease marked by bleeding around the gums and loose
teeth. Now, a new study may further boost vitamin C's
reputation with results that it may also reduce high
| VITAMIN C|
Food sources: Citrus fruits and many other fruits and vegetables, including berries, melons, peppers, many dark green leafy vegetables, potatoes and tomatoes.
Deficiency problems: Scurvy, a disease that causes loose teeth, excessive bleeding, swollen gums and improper wound healing.
Excess amounts: May cause diarrhea and gastrointestinal discomfort. Use of supplements can also interfere with tests for blood sugar level.
From the American Dietetic Association
Researchers from the Boston University School of
Medicine and Oregon State University studied 39
patients with mild to moderate hypertension. About
half of the patients took daily doses of 500 mg of
vitamin C, also known as ascorbic acid, while the
other half took a placebo.
After one month, the
average blood pressure of patients who took vitamin C
dropped significantly more than that of patients in
the placebo group, or 9.1 percent compared to 2.7
Patients who took vitamin C also had approximately
twice the level of ascorbic acid in their blood as
those in the placebo group.
Works in conjunction, not alone
The findings, published in this week's journal Lancet,
could be explained by the ability of vitamin C to
"improve the biologic activity of nitric oxide," said
co-author Balz Frei, Ph.D., professor of biochemistry
and director of the Linus Pauling Institute at Oregon
Blood vessels require nitric oxide
to relax or dilate, Frei said. "If nitric oxide is
impaired, you fail to relax the artery, and that can
result in increased blood pressure."
Frei said vitamin C might also work well in
conjunction with current
prescription anti-hypertension medications. Patients
from both study
groups continued taking their anti-hypertension
medications during the trial.
Whatever the mechanism, the reduction in blood
pressure was "impressive," said Norman Kaplan, M.D.,
clinical professor of internal medicine at the
University of Texas Southwestern Medical Center at
Dallas and a leading expert in hypertension.
Kaplan said previous studies have linked a decrease in
blood pressure to higher levels of vitamin C in the
"It's a presumably non-dangerous approach [to reducing
blood pressure], but my recommendation is to eat more
fruits and vegetables rather than take supplements,"
he said. "Nature's best, and it's cheaper."
Foods rich in vitamin C include citrus fruits, green
peppers, broccoli, tomatoes and strawberries.
A dosage debate
The vitamin C dosage used in the study was more than
eight times greater than the recommended daily
allowance (RDA) of 60 mg for the adult diet, but
smaller than some of the 2,000 to 10,000 mg megadoses
many vitamin advocates recommend.
The proper dosage of vitamin C in the diet has been a
subject of much
debate in the medical community.
Eight months ago,
researchers from the
National Institutes of Health recommended raising the
RDA for vitamin C to between 100 mg and 200 mg. At the
same time, many health experts say doses greater than
200 mg are useless at best, and potentially harmful.
In 1998, a widely publicized study in the journal
Nature linked daily doses of 500 mg of vitamin C to
DNA damage. The results and methodology of that study
have since been criticized, but many medical experts
remain skeptical about pumping up the intake of
Medications still crucial
Alice Lichtenstein, D.Sc., a spokesperson for the
Association and professor of nutrition at Tufts
University, said she
knows of no data to suggest amending the current
guidelines for vitamin C. She also cautioned against
shunning conventional blood pressure medications based
upon the findings published in Lancet.
"It's an interesting study, but it needs to be
replicated with a more
diverse population," she said.
Frei agreed, stating that "a single study can never
give you a final
answer. We would like to see more, larger studies, and
then we'd have more confidence to really recommend
this to patients with hypertension."
Copyright 1999 Healtheon/WebMD. All rights reserved.
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