More surprising news on the nutrition front.....

[RACastanet]

Now a study indicates that high levels of vitamin C may lead to thickening of the carotid arteries. And another is linking coffee consumption to rheumatoid arthritus. What do our esteemed doctors and known java consumers have to say about this?????

Nothing is sacred any more.

It is back to red meat and Kool-Aid for me.

Rich C.

[Ian]

A few things to consider, keeping in mind that I HAVE NOT read these studies and don't know if we're talking vitamin C megadoses or what:

1) how sure are we of the results--what was the study design, what was the p value, was this a small effect picked out in a study designed to look for something else...

A while back there was a study looking at alcohol, smoking and pancreatic cancer which also assessed for coffee use, mainly because they thought it'd be associated with the others. Turns out it was the only impressive link, and much was made out of it even though, since it wasn't the focus of the study, duration adn intensity of use weren't adequately assessed.

Later when a decent study was done looking for the same, the result (no link) was buried in page 5 bazillion not blared on the front page.

2) What is the strength of the link? If we're absolutely SURE some level of vitamin C intake causes a .003% increase in disease x, I'm still not impressed. Especially because:

3) was there an overall mortality/morbity difference shown? If not, a diet high in vitamin C may well have some damaging effects that are easily outweighed by multiple benefits. An analogy: there was a truck (ford?) with the gas tank outside of the frame with a much higher risk of death by fire that was pulled from the market because of this high death risk. The overall death risk was lower than the average for the cars left on the market.

Lastly, I assume you're kidding, but if you really want to harden your carotids, red meat is the way to go and watch out for the vitamin C supplements in Kool aid.

[Bill Glasheen]

Rich

Please give your references.

Actually I heard the comment about coffee consumption and rheumatoid arthritis. Who knows what the heck that one is... R.A. is an autoimmune disease, and the medical community has yet to fully understand the cause of this class of illnesses. It could be viral, it could be genetic, it could be environmental, it could be a combination....

Another thing to remember - there's a big difference between association and causality. For instance, a study I did years ago showed blacks to have a much greater risk of burn injuries than whites. Does this point out a genetic flaw in blacks that predisposes them to fire jumping out from behind the bushes and torching them? Of course not. In the case of my study, race was a proxy for socioeconomic status. So the link was an association which pointed to the real cause. The same could be for the coffee, if the study was done well. Actually I'm willing to bet that it was an epidemiologic study rather than a randomized trial. In other words, somebody looked at years of data sitting around about people with and without R.A., and stumbled on a higher-than-normal relative risk for coffee drinkers. That's a start, but it proves nothing. In many cases, such studies only show selection biases in the design.

As for the Vitamin C thing, I need to see the original study first. However I'm willing to make a few comments. People need to understand that there is a right dose for everything. Even small doses of Vitamin A (as opposed to beta carotene) given to pregnant women has been shown to be associated with a higher-than-normal rate of birth defects. There are also case histories of death from too much Vitamin A consumption (eating polar bear liver). Too much of a certain B Vitamin (B6??) can cause a rare neurological disease. Too much Vitamin C can lead to kidney stones and to diarrhea. To much Vitamin D and E can lead to similar toxic effects. For many of the antioxidant vitamins, there is an optimal dose. In some cases, substances that have antioxidant properties at a certain dose will have free radical properties at megadoses.

Just last Sunday my wife showed me a published case history of a kid who took megadoses of creatine for an extended period of time. He took 8 weeks off from the gym, and then came back and did a 3 hour workout. He ended up in the hospital with compartment syndrome in the quadriceps, symptoms similar to those encountered with rabies, and eventually renal failure. Now this is only an anecdote but...

Moral of the story - if a certain dose is good, then more is not necessarily better.

- Bill

[Susie Harrison]

There was a very interesting study done by James Dwyer, MD from California on Vitamin C. He found that after a one-year period of supplementation (placebo-controlled) with vitamin C, that those who received supplements exhibited significantly more thickening of the arteries in the neck compared to placebo. Those receiving the highest dosage (480mg) had thickening that was 3 times that of the placebo group. It wasn't the carotid arteries that were measured, but other neck arteries.
Pretty scary - thick arteries have narrower openings and are less flexible than normal. His study has led to caution in terms of recommendations of vitamin C supplements. I know that I certainly advise my clients not to exceed 200mg daily in supplement form, and find that many don't require a supplement at all.



[This message has been edited by Susie Harrison (edited August 06, 2000).]

[RACastanet]

Thank you for the background Susie.
Regards, Rich