Featured Research

from universities, journals, and other organizations

Vitamin C Worsens Knee Osteoarthritis In Animal Study

June 7, 2004
Duke University Medical Center
High doses of vitamin C increase the severity of spontaneous knee osteoarthritis in an animal model of the disease, according to a new study by Duke University Medical Center researchers.

DURHAM, N.C. -- High doses of vitamin C increase the severity of spontaneous knee osteoarthritis in an animal model of the disease, according to a new study by Duke University Medical Center researchers.

Related Articles

The results contradict previous short-term studies in guinea pigs and an epidemiologic study in humans that suggested vitamin C might protect against osteoarthritis, said lead investigator Virginia Kraus, M.D., associate professor of medicine at Duke University Medical Center. The study was published in the June 2004 issue of Arthritis & Rheumatism. The research was sponsored by the Arthritis Foundation and the National Institutes of Health.

In the Duke study, the researchers fed guinea pigs -- which develop knee osteoarthritis in a manner remarkably similar to humans -- low, medium and high doses of vitamin C during an eight-month period. The researchers found that high-dose guinea pigs developed more cartilage damage and had more bony spurs form in their knee joints than did the medium- and low-dose groups. The researchers' examination of the spurs revealed a possible cause for the link between vitamin C and osteoarthritis. They discovered a protein in the spurs that leads to spur formation and can be activated by vitamin C.

Because this study indicates potential drawbacks to long-term use of high-dose vitamin C supplements, adults should not supplement their dietary vitamin C levels above the recommended dietary allowance (RDA), Kraus said. The RDA for men is 90 milligrams per day and the RDA for women is 75 milligrams per day. A diet that includes five servings of fruits and vegetables a day supplies about 200 milligrams per day of vitamin C.

"It's possible that brief exposure to high levels of vitamin C offers antioxidant effects with a minimum of side effects, while prolonged exposure results in deleterious effects," Kraus said. A randomized, controlled clinical trial in humans would be required to definitely resolve the issue of vitamin C dosing, she said.

Like humans, the Hartley strain of guinea pigs lack a gene for making vitamin C, leaving them dependent on vitamin C in their diet. Each of the 46 guinea pigs followed in the study were fed standard chow supplemented by a custom-made food with three different concentrations of ascorbic acid (vitamin C). The study began when the guinea pigs were 4 months old.

The medium dose, 30 milligrams per day, was the guinea pig equivalent of the RDA for vitamin C in humans -- comparable to a person consuming five fruit and vegetable servings. The lower dose, about three milligrams per day, was the minimum necessary to prevent scurvy in the guinea pigs. The high dose was 150 milligrams per day, an amount shown to protect against surgically-induced osteoarthritis in a short-term guinea pig study. The equivalent human dose is 1,500 to 2,500 milligrams per day.

The antioxidant properties of vitamin C were posited as one explanation for the earlier positive results, because oxygen radicals can degrade collagen and proteoglycan, a connective tissue protein. The vitamin has also been shown to help collagen synthesis and stimulate production of key components of collagen.

The Duke researchers did find an association between higher levels of vitamin C and increasing collagen in knee cartilage. However, there was also a strong correlation between vitamin C dose and the severity of disease, including the number and size of osteophytes, or bony spurs at the knee joint. The researchers found an important protein in bone growth called active transforming growth factor beta almost exclusively in the osteophytes. The protein is known to cause joint degeneration and spur formation, and vitamin C can convert this protein from an inactive to an active state, Kraus said. This conversion means that vitamin C's ability to enhance collagen synthesis and activate transforming growth factor beta might be the reason guinea pigs fed high doses of vitamin C developed more osteoarthritis, she said.

Another factor considered in the study was the role of weight as a risk for osteoarthritis. The guinea pigs fed a low dose of vitamin C had a lower mean weight from 5 months to 8 months of age than the other guinea pig groups. Thus, the researchers cannot rule out weight as a protective factor for osteoarthritis between the low dose group and the other guinea pig groups. Still, the weights of the medium dose and high dose guinea pig groups were similar throughout the study, and analyses restricted to these two groups showed a significant worsening of osteoarthritis with increasing levels of vitamin C.

Collaborators on the study include Janet Huebner, Thomas Stabler, Charlene Flahiff, Loria Setton, Christian Fink and Amy Clark, all of Duke. Vladimir Vilim of the Institute of Rheumatology in Prague also contributed to the research.

Story Source:

The above story is based on materials provided by Duke University Medical Center. Note: Materials may be edited for content and length.

Cite This Page:

Duke University Medical Center. "Vitamin C Worsens Knee Osteoarthritis In Animal Study." ScienceDaily. ScienceDaily, 7 June 2004. <www.sciencedaily.com/releases/2004/06/040604030442.htm>.
Duke University Medical Center. (2004, June 7). Vitamin C Worsens Knee Osteoarthritis In Animal Study. ScienceDaily. Retrieved March 30, 2015 from www.sciencedaily.com/releases/2004/06/040604030442.htm
Duke University Medical Center. "Vitamin C Worsens Knee Osteoarthritis In Animal Study." ScienceDaily. www.sciencedaily.com/releases/2004/06/040604030442.htm (accessed March 30, 2015).

Share This

More From ScienceDaily

More Health & Medicine News

Monday, March 30, 2015

Featured Research

from universities, journals, and other organizations

Featured Videos

from AP, Reuters, AFP, and other news services

Soda, Salt and Sugar: The Next Generation of Taxes

Soda, Salt and Sugar: The Next Generation of Taxes

Washington Post (Mar. 30, 2015) — Denisa Livingston, a health advocate for the Dinι Community Advocacy Alliance, and the Post&apos;s Abby Phillip discuss efforts around the country to make unhealthy food choices hurt your wallet as much as your waistline. Video provided by Washington Post
Powered by NewsLook.com
UnitedHealth Buys Catamaran

UnitedHealth Buys Catamaran

Reuters - Business Video Online (Mar. 30, 2015) — The $12.8 billion merger will combine the U.S.&apos; third and fourth largest pharmacy benefit managers. Analysts say smaller PBMs could also merge. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
S. Leone in New Anti-Ebola Lockdown

S. Leone in New Anti-Ebola Lockdown

AFP (Mar. 28, 2015) — Sierra Leone imposed a three-day nationwide lockdown Friday for the second time in six months in a bid to prevent a resurgence of the deadly Ebola virus. Duration: 01:17 Video provided by AFP
Powered by NewsLook.com
These Popular Antibiotics Can Cause Permanent Nerve Damage

These Popular Antibiotics Can Cause Permanent Nerve Damage

Newsy (Mar. 27, 2015) — A popular class of antibiotic can leave patients in severe pain and even result in permanent nerve damage. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.


Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News


Free Subscriptions

Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile

Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?

Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins