This makes two in one week:
In yet another example of contradictory research, some scientists now believe that beta carotene does not offer any benefit in the fight against cancer. Prior to some of these new findings, all previous data I came across (and still continue to come across) posits just the opposite.
Beta carotene, an antioxidant found in such foods as squash and carrots, was -- and still is, in some circles -- considered a powerful cancer fighter and a combatant against free-radical damage. While the evidence regarding the latter still, at least ostensibly, holds true, some new research suggests that beta-carotene is completely ineffective as a cancer fighter (of course, it can be argued that by helping to fight against free-radical damage, beta carotene is also battling against the increased risk of developing cancer). Just the same, what is perhaps the even more shocking discovery is that beta carotene may actually increase the chances of lung cancers in smokers (note: beta carotene, although not effective in battling cancer, demonstrated signs of increasing lung cancer risk in smokers only. There was no evidence to suggest that beta carotene could increase one's risk of developing any other type of cancer. Simply, it just won't help fight it against it, though.).
Too many studies, too many dissenting opinions. All we want is accurate, well-researched information. Is that too much to ask?
1. Chris,
It's important to get the message out that beta carotene and smoking don't mix, as your blog does so well, but knowledge of the link between beta carotene and greater lung cancer risk for smokers is not new, though further evidence comes up from time to time that further bolsters the earlier findings.
You can check in PubMed, and this is one abstract that describes the original finding back in 1996:
J Natl Cancer Inst. 2004 Dec 1;96(23):1743-50
The Beta-Carotene and Retinol Efficacy Trial: incidence of lung cancer and cardiovascular disease mortality during 6-year follow-up after stopping beta-carotene and retinol supplements.Goodman GE, Thornquist MD, Balmes J, Cullen MR, Meyskens FL Jr, Omenn GS, Valanis B, Williams JH Jr.
"...Beta-Carotene and Retinol Efficacy Trial (CARET) tested the effect of daily beta-carotene (30 mg) and retinyl palmitate (25,000 IU) on the incidence of lung cancer, other cancers, and death in 18,314 participants who were at high risk for lung cancer because of a history of smoking or asbestos exposure. CARET was stopped ahead of schedule in January 1996 because participants who were randomly assigned to receive the active intervention were found to have a 28% increase in incidence of lung cancer, a 17% increase in incidence of death and a higher rate of cardiovascular disease mortality compared with participants in the placebo group...."
As you can see, more than 18,000 participants were studied in the CARET trial, and I'm not aware of any serious, substantial questions about the quality of the trial (though this is not an area I follow closely). The CARET trial is probably the kind of quality research you (and I) hope to see more of.
Jim Waldenfels (web site: http://www.mycancerplace.com/profile.php?id=147)
Posted at 5:20PM on Dec 7th 2006 by Jim Waldenfels