Carotenoids cancer prevention

It is well known that excessive intake of P-carotene may lead to carotenodermia (yellow skin), and it is undoubtedly the case that some carotenoid is directly lost via the skin or through photo-oxidation in the skin. As far as is known the carotenoids are not cytotoxic or genotoxic even at concentrations up to 10 times the normal plasma concentration which may cause carotenodermia. However, they are associated with amenorrhoea in girls who may be consuming bizarre diets and, in long-term supplementation studies, with an increase in lung cancer (The Alpha-tocopherol, Beta-carotene Cancer Prevention Study Group, 1994). 

Epidemiological data on carotenoids and cerebral infarcts or strokes indicate a protective effect of P-carotene and lycopene. Indeed, the Basel prospective study, the Kuopio Ischaemic Heart Disease Risk Factor study, and the Physicians Health Study " have shown an inverse correlation between carotenoid plasma level and risk of stroke. In the same way, Hirvonen et al. demonstrated, in findings from the ATBC cancer prevention stndy, an inverse association between P-carotene dietary intake and stroke. However, clinical data on carotenoids and stroke are nonexistent and they are needed to confirm this possible protective effect of carotenoids on stroke. 

King, T.J. et al., Metabolites of dietary carotenoids as potential cancer preventive... 

Bertram, J.S. and Vine, A.L., Cancer prevention by retinoids and carotenoids independent action on a common target, Biochim. Biophys. Acta 1740, 170, 2005. 

Albanes, D. et al., Effect of supplemental P-carotene, cigarette smoking and alcohol consumption on serum carotenoids in alpha-tocopherol, P-carotene cancer prevention study, Am. J. Clin. Nutn, 66, 366, 1976. 

Weisbutger, J.H. (1991). Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants, and carotenoids. Am. J. Clin. Nutr. 53, 226S-237S. 

Other dietary factors implicated in prostate cancer include retinol, carotenoids, lycopene, and vitamin D consumption.5,6 Retinol, or vitamin A, intake, especially in men older than age 70, is correlated with an increased risk of prostate cancer, whereas intake of its precursor, [3-carotene, has a protective or neutral effect. Lycopene, obtained primarily from tomatoes, decreases the risk of prostate cancer in small cohort studies. The antioxidant vitamin E also may decrease the risk of prostate cancer. Men who developed prostate cancer in one cohort study had lower levels of l,25(OH)2-vitamin D than matched controls, although a prospective study did not support this.2 Clearly, dietary risk factors require further evaluation, but because fat and vitamins are modifiable risk factors, dietary intervention may be promising in prostate cancer prevention. 

The interaction of carotenoids with cigarette smoke has become a subject of interest since the results of the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study Group 1994 (ATBC) and CARET (Omenn et al. 1996) studies were released. P-Carotene has been hypothesized to promote lung carcinogenesis by acting as a prooxidant in the smoke-exposed lung. Thus, the autoxidation of P-carotene in the presence of cigarette smoke was studied in model systems (toluene) (Baker et al. 1999). The major product was identified as 4-nitro-P-carotene, but apocarotenals and P-carotene epoxides were also encountered. 

Zhang, LX, RV Cooney, and JS Bertram. 1991. Carotenoids enhance gap junctional communication and inhibit lipid peroxidation in C3H/10T1/2 cells Relationship to their cancer prevention action. Carcinogenesis 12(11 ) 2109—2114. 

Extensive research in the last few years has revealed that the regular consumption of certain fruits containing carotenoids, an important group of phytochemicals derived from such fruits and vegetables, is involved in cancer prevention. Both prospective and retrospective epidemiological studies have consistently and clearly shown that an increased intake of fruits and vegetables rich in carotenoids is associated with a decreased risk of cancer (Mayne, 1996 Peto... 

It has been shown that the expression of connexin 43 (Cx43) is upregulated by cancer-preventive retinoids and carotenoids, which correlate with the suppression of carcinogen-induced transformation in 10T1/2 cells. Recently, it has been reported that Cx43 induction by astaxanthin, but not by a RAR-specific retinoid, was inhibited by GW9662, a PPARy antagonist (Bertram et al., 2005). 

Albanes D, Virtamo J, Taylor PR, Rautalahti M, Pietinen P and Heinonen OP. 1997. Effects of supplemental 3-carotene, cigarette smoking, and alcohol consumption on serum carotenoids in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Am J Clin Nutr 66 366—372. 

H. Nishino, H. Tokuda, Y. Satomi, M. Masuda, P. Bu, M.Onozuka, S. Yamaguchi, Y. Okuda, J. Takagasu, J. Tusututa, M. Okuda, E. Ichishi, M. Murakoshi, T. Kato, N. Misawa, T. Narisawa and N. Takasuka, Cancer prevention by carotenoids. Pure Appl. Chem. 71 (1999) 2273-2278. 

Astrog, P. 1997. Food carotenoids and cancer prevention an overview of current research. Trends Food Sci. Technol.,8, 406-413. 

Carotenoids (especially p-carotene) find widespread applications in food industry. These pigments not only give an attractive color to a wide variety of food products but it is also known that p-carotene and various other members of this substance family play an important role in cancer prevention. 

Khachik, F. et al.. Distribution of carotenoids in fruits and vegetables as a criterion for the selection of appropriate chemopreventive agents, in Food Factors for Cancer Prevention, Ohigashi, H., Osawa, T., Terao, J., Watanabe, S., Yoshikawa, T., Eds., Springer-Verlag, Tokyo, 1997, p. 204. 

Carotenoids, Vol 2, lARC Handbooks of Cancer Prevention International Agency for Research on Cancer, 7998 ISBN 92-832-0027 and 1207-5622. 

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