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Carcinogenesis. 1997 Sep;18(9):1847-50.

Consumption of vegetables reduces genetic damage in humans: first results of a human intervention trial with carotenoid-rich foods.

Pool-Zobel BL, Bub A, Müller H, Wollowski I, Rechkemmer G.

Institute of Nutritional Physiology, Federal Research Centre for Nutrition, Karlsruhe , Germany .

A human intervention study with vegetable products has been performed in twenty three healthy, non smoking males aged 27-40. It was the aim of the study to assess whether consumption of vegetables containing different carotenoids could protect against DNA damage and oxidative DNA damage. The subjects consumed their normal diets, but abstained from vegetables high in carotenoids throughout the study period. After a 2 week depletion period, they received daily 330 ml tomato juice with 40 mg lycopene (weeks 3 and 4), 330 ml carrot juice with 22.3 mg beta-carotene and 15.7 mg alpha-carotene (weeks 5 and 6), and 10 g dried spinach powder (in water or milk) with 11.3 mg lutein (weeks 7 and 8). Blood was collected weekly and DNA damage was detected in peripheral blood lymphocytes with the 'COMET' assay. Oxidised DNA bases were detected by including an incubation step with endonuclease III. The supplementation of the diet with tomato, carrot or spinach products resulted in a significant decrease in endogenous levels of strand breaks in lymphocyte DNA. Oxidative base damage was significantly reduced during the carrot juice intervention. These findings support the hypothesis that carotenoid containing plant products exert a cancer-protective effect via a decrease in oxidative and other damage to DNA in humans .

Source: PubMed

Nutr Cancer. 1997;27(3):238-44.

Effects of carotenoid-rich food extracts on the development of preneoplastic lesions in rat liver and on in vivo and in vitro antioxidant status.

He Y, Root MM, Parker RS, Campbell TC.

Division of Nutritional Scinces, Cornell University , Ithaca , NY 14853 , USA .

The effect of dietary carotenoid-rich extracts of carrots, tomatoes, and orange juice on rat liver gamma-glutamyl transpeptidase-positive preneoplastic foci induced by aflatoxin B1 was investigated. Organic extracts were prepared from the foods, dissolved in tricaprylin oil to equivalent concentrations of the major food-specific carotenoids, and fed by intubation to Fischer 344 male rats. The extracts were administered during the 2-week aflatoxin-dosing (initiation) period of the study or during the subsequent 12-week post-dosing (promotion) period. Vitamin status and antioxidant activities were measured in blood and liver. Extract feeding caused an accumulation of carotenoids in the liver, a substantial decrease in spontaneous erythrocyte hemolysis, and lowered plasma glutathione, blood superoxide dismutase, and blood catalase. Differences in foci development among the three extracts were not as consistent or profound as differences between initiation and promotion dosing. The number of gamma-glutamyl transpeptidase-positive foci was decreased by extract feeding during the initiation period, whereas extract feeding during the promotion period caused a decrease in the average diameter of the foci. The total volume of foci was markedly reduced by extract feeding during either period. Extracts were compared with purified carotenoids and alpha-tocopherol in their ability to affect in vitro antioxidation activity and were nearly as effective as the pure compounds. In summary, carotenoid-rich extracts of these three foods substantially inhibited biochemical and cellular events thought to play a role in the early stages of hepatocarcinogenesis [Liver cancer].

Source: PubMed