Parnaud G, Peiffer G, Taché S, Corpet D E
Laboratoire Sécurité des Aliments, Institut National de la Recherche Agronomique, Ecole Nationale Vétérinaire, Toulouse, France.
Nutr Cancer. 1998;32(3):165-73. doi: 10.1080/01635589809514736.
High intake of red meat or processed meat is associated with increased risk of colon cancer. In contrast, consumption of white meat (chicken) is not associated with risk and might even reduce the occurrence of colorectal cancer. We speculated that a diet containing beef or bacon would increase and a diet containing chicken would decrease colon carcinogenesis in rats. One hundred female Fischer 344 rats were given a single injection of azoxymethane (20 mg/kg i.p.), then randomized to 10 different AIN-76-based diets. Five diets were adjusted to 14% fat and 23% protein and five other diets to 28% fat and 40% protein. Fat and protein were supplied by 1) lard and casein, 2) olive oil and casein, 3) beef, 4) chicken with skin, and 5) bacon. Meat diets contained 30% or 60% freeze-dried fried meat. The diets were given ad libitum for 100 days, then colon tumor promotion was assessed by the multiplicity of aberrant crypt foci [number of crypts per aberrant crypt focus (ACF)]. The ACF multiplicity was nearly the same in all groups, except bacon-fed rats, with no effect of fat and protein level or source (p = 0.7 between 8 groups by analysis of variance). In contrast, compared with lard- and casein-fed controls, the ACF multiplicity was reduced by 12% in rats fed a diet with 30% bacon and by 20% in rats fed a diet with 60% bacon (p < 0.001). The water intake was higher in bacon-fed rats than in controls (p < 0.0001). The concentrations of iron and bile acids in fecal water and total fatty acids in feces changed with diet, but there was no correlation between these concentrations and the ACF multiplicity. Thus the hypothesis that colonic iron, bile acids, or total fatty acids can promote colon tumors is not supported by this study. The results suggest that, in rats, beef does not promote the growth of ACF and chicken does not protect against colon carcinogenesis. A bacon-based diet appears to protect against carcinogenesis, perhaps because bacon contains 5% NaCl and increased the rats' water intake.
红肉或加工肉类的高摄入量与结肠癌风险增加有关。相比之下，食用白肉（鸡肉）与风险无关，甚至可能降低结直肠癌的发生率。我们推测，含有牛肉或培根的饮食会增加大鼠结肠癌的发生，而含有鸡肉的饮食会减少其发生。100只雌性Fischer 344大鼠单次腹腔注射偶氮甲烷（20毫克/千克），然后随机分为10种基于AIN-76的不同饮食组。5种饮食调整为14%脂肪和23%蛋白质，另外5种饮食调整为28%脂肪和40%蛋白质。脂肪和蛋白质由以下提供：1）猪油和酪蛋白，2）橄榄油和酪蛋白，3）牛肉，4）带皮鸡肉，5）培根。肉类饮食含有30%或60%的冻干油炸肉。随意喂食这些饮食100天，然后通过异常隐窝灶的数量（每个异常隐窝灶的隐窝数量）评估结肠肿瘤的促进情况。除喂培根的大鼠外，所有组的异常隐窝灶数量几乎相同，脂肪和蛋白质水平或来源均无影响（方差分析8组间p = 0.7）。相比之下，与喂猪油和酪蛋白的对照组相比，喂30%培根饮食的大鼠异常隐窝灶数量减少了12%，喂60%培根饮食的大鼠减少了20%（p < 0.001）。喂培根的大鼠的饮水量高于对照组（p < 0.0001）。粪便水中铁和胆汁酸的浓度以及粪便中总脂肪酸的浓度随饮食而变化，但这些浓度与异常隐窝灶数量之间没有相关性。因此，本研究不支持结肠铁、胆汁酸或总脂肪酸可促进结肠肿瘤的假说。结果表明，在大鼠中，牛肉不会促进异常隐窝灶的生长，鸡肉也不能预防结肠癌的发生。基于培根的饮食似乎可以预防癌变，可能是因为培根含有5%的氯化钠并增加了大鼠的饮水量。
