可可粉是巧克力的成分之一，可可粉中含有很多黄酮类成分，还包括如原花青素、儿茶酚等在预防心血管疾病中发挥重要作用的化学成分。
近日，一项由食品科学技术与营养协会科研人员主持的研究表明：实验动物在摄取可可粉后，可以帮助动物预防因氧化性应激损伤有关的肠道疾病，对化学致癌物质诱发的结肠癌有预防作用。相关研究论文发表在Molecular Nutrition & Food Research杂志上。
研究人员用小鼠动物实验首次证实了可可粉中的黄酮类成分有预防结肠癌的功效。实验开始时，工作人员一直用含可可粉的饲料（含量占12%）喂养小鼠，8周后用化学复合物氧化偶氮甲烷诱导小鼠肿瘤发生。
用化学药物诱导刺激小鼠4周后，正常对照小鼠肿瘤病变前肠道部位开始出现肠道粘液，肠道粘液是结肠癌发病的标志物。而用含可可粉当饲料的小鼠在致癌剂的诱导下，小鼠出现结肠癌的只数明显少于对照组。同时研究人员在食用含可可粉当饲料的小鼠体内发现，内源性的抗氧化剂水平提高了，致癌剂诱导的氧化损伤标志物水平减少了，小鼠防御致癌剂损伤的能力有所提升。
研究员根据这一结果猜测可可粉的预防癌症发生的作用可能与阻断细胞增殖过程中的信号转导途径有关。用含可可粉的饲料喂养动物后，动物体内明显出现细胞凋亡或细胞程序性死亡加剧现象，这有可能是可可粉抑制癌症发生的化学预防机制。但研究中未明确到底是可可粉中的哪种生物活性化合物起到了抑癌的化学预防作用。（生物谷Bioon.com）
doi:10.1002/mnfr.201100363
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Cocoa-rich diet prevents azoxymethane-induced colonic preneoplastic lesions in rats by restraining oxidative stress and cell proliferation and inducing apoptosis
Ildefonso Rodríguez-Ramiro1, Sonia Ramos1, Elvira López-Oliva2, Angel Agis-Torres2, Miren Gómez-Juaristi1, Raquel Mateos1, Laura Bravo1, Luis Goya1, María ángeles Martín1,3,*
Cocoa is a rich source of bioactive compounds with potential chemopreventive ability but up to date its effectiveness in animal models of colon carcinogenesis has not been addressed. Herein, we investigated the in vivo effect of a cocoa-rich diet in the prevention of azoxymethane (AOM)-induced colon cancer and the mechanisms involved. Our results showed that cocoa feeding significantly reduced AOM-induced colonic aberrant crypt foci formation and crypt multiplicity. Oxidative imbalance in colon tissues seems to be prevented by cocoa as indicated by reduced oxidation markers levels and increased enzymatic and non-enzymatic endogenous defences. Cocoa-rich diet also exhibited antiproliferative effects by decreasing the levels of extracellular regulated kinases, protein kinase B and cyclin D1 together with pro-apoptotic effects evidenced by reduced Bcl-xL levels and increased Bax levels and caspase-3 activity. Our findings provide the first in vivo evidence that a cocoa-rich diet may inhibit the early stage of colon carcinogenesis probably by preventing oxidative stress and cell proliferation and by inducing apoptosis.
