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