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Guinea pig in a poke

I have some troubling news for those of you who are giving your guinea pigs high doses of vitamin C: They may be at risk of developing knee osteoarthritis (OA), according to a new study from the Duke University Medical Center.

If you’re taking vitamin C in large doses yourself, however, should you be concerned about your own knees?

Yes, say the Duke researchers. In their conclusion, they write that the study outcome, “suggests that ascorbic acid intake should not be supplemented above the currently recommended dietary allowance (90 mg/day for men and 75 mg/day for women).”

That’s YOU they’re talking about, not your guinea pig. And this “advice” is based on one guinea pig study, which happens to contradict an earlier study.

And if you’re thinking this sounds like a guinea pig in a poke, you’re absolutely right.

Game, set and match

Here are the basics on the Duke study, as reported in the journal Arthritis & Rheumatism:

Over a period of eight months, a group of guinea pigs were fed either low, medium, or high doses of ascorbic acid. Those who received low and medium doses had no knee problems. Perhaps they’re now enjoying tennis and skydiving. Meanwhile, the guinea pigs in the high dose group experienced the activation of a protein called TGF-beta. And because latent TGF-beta has been shown to be activated by ascorbic acid, and because TGF-beta has been linked to “OA- like changes,” an increase of cartilage collagen in the guinea pigs was attributed to the highest dose of vitamin C.

The researchers note that their results are the exact opposite of those in a previous ascorbic acid study that found ascorbic acid to SLOW the progression of OA in guinea pigs. Nevertheless, they still finish up their conclusions with a recommendation that men and women should not exceed the very low vitamin C RDA, set by the U.S. Department of Agriculture.

Does that recommendation strike you as a little too easy? And very premature?

Funny that’s how it strikes me too.

What a racquet!

Knowing that HSI Panelist Allan Spreen, M.D., regards vitamin C as one of the most basic and useful nutrients you can incorporate into your diet and supplement regimen, I asked him if he had an opinion on this study. His response nearly rattled the windows. In Dr. Spreen’s own words:

“More propaganda from the drug world.

“First, the study is funded from 3 sources: the Arthritis Foundation and the National Institutes of Health are two, both of which are thoroughly controlled by the pharmaceutical industry (in my opinion). I don’t know the source of the third grant’s funding, but I assure you it isn’t a vitamin company.

“Second, it’s already established that the same amount of vitamin C DOES help osteoarthritis, so AT MOST nothing can be determined until a ‘tie-breaker’ study helps settle the issue (hopefully not one associated with drug companies, but don’t hold your breath).

“The conclusion is to stay with the RDA (90 milligrams for men, 75 for women). What garbage, when drug companies control the ‘official’ therapy line.

“If ‘long term’ high-dose C causes arthritis (any type), it better hurry. I have as bad a set of knees as most anyone; one operated on arthroscopically, and the other using the older ‘open’ surgical technique, where they remove the entire cartilage instead of just shaving out the inner edge). I also have not taken LESS than 3,000 (up to 9,000) milligrams of vitamin C daily for the last 30 years, and my knees tolerate as much racquetball as my out-of-shape body can take.

“However, that’s anecdotal. The real evidence is the motive of those funding the studies. Why would anyone care to try disproving such a thesis as using a nutrient to treat arthritis? It’s just more of the same.”

Not right in the head

And under the heading of “Just more of the same” I have to also sound off on one of my pet peeves: misleading headlines.

Here’s the headline that topped MSNBC’s coverage of the Duke study:

“Vitamin C May Worsen Arthritis, Study Finds”

That is so far off the mark it’s ridiculous. Think of how many people with arthritis may have seen that headline and now believe that vitamin C might be bad for them.

Meanwhile, one week later, Reuters Health reported a UK study with this headline:

“Vitamin C Rich Diet May Cut Arthritis Risk”

Quite a contrast, huh? And the studies provide quite a contrast as well: The Duke study used guinea pigs, while the UK study followed the diets and medical records of more than 200 HUMAN subjects for about seven years.

Like Dr. Spreen, my knees are not in the best shape. Nevertheless, I’ll take my chances with a “vitamin C rich diet.”

As for my guinea pigs that’s another story.

“Ascorbic Acid Increases the Severity of Spontaneous Knee Osteoarthritis in a Guinea Pig Model” Arthritis & Rheumatism, Vol. 50, No. 6, 6/3/04,
“Vitamin C May Worsen Arthritis, Study Finds” Reuters Health, 6/4/04,
“Vitamin C and the Risk of Developing Inflammatory Polyarthritis: Prospective Nested Case-Control Study” Annals of the Rheumatic Diseases, Vol. 63, No. 7, July 2004,
“Vitamin C Rich Diet May Cut Arthritis Risk” Anthony J. Brown, M.D., Reuters Health, 6/12/04,