"Juhana Harju" > wrote in message
...
> John Que wrote:
> ::: The Finnish study was done with isolated beta carotene supplements
> ::: and the beta carotene was not in its natural form. Beta carotene
> ::: from food sources is perfectly alright.
> :::
> :: all trans-beta carotene.
> ::
> :: natural would be a mix of trans and cis
>
> That's right. This is the Finnish Study:
>
> The effect of vitamin E and beta carotene on the incidence of lung
> cancer and other cancers in male smokers. The Alpha-Tocopherol, Beta
> Carotene Cancer Prevention Study Group. N Engl J Med. 1994 Apr
> 14;330(15):1029-35. PMID: 8127329
>
> "Unexpectedly, we observed a higher incidence of lung cancer among the
> men who received beta carotene than among those who did not."
>
>
http://www.ncbi.nlm.nih.gov/entrez/q...t_uids=8127329
>
> But there are also studies where an *inverse* relationship between beta
> carotene and lung cancer was found, so the situation is not so clear:
>
> Connett JE, Kuller LH, Kjelsberg MO, Polk BF, Collins G, Rider A, Hulley
> SB. Relationship between carotenoids and cancer. The Multiple Risk
> Factor Intervention Trial (MRFIT) Study. Cancer. 1989 Jul
> 1;64(1):126-34. PMID: 2731108
>
> "The results of this study provide further evidence for a possible
> protective effect of beta carotene against lung cancer among cigarette
> smokers."
>
> Menkes MS, Comstock GW, Vuilleumier JP, Helsing KJ, Rider AA, Brookmeyer
> R. Serum beta-carotene, vitamins A and E, selenium, and the risk of lung
> cancer. N Engl J Med. 1986 Nov 13;315(20):1250-4. PMID: 3773937
>
> --
> Juhana

The positive reports are based on correlation.
The old saying goes " correlation doesn't prove causation."
Now that I've said that, I state the obvious which you
are aware. The 1986 and 1989 studies are based
the dietary source apparently. The involved beta carotenoid
would be both trans and cis. There would likely be
a great mix of carotenoids especially in the diets of
the healthier subjects.
>