Authors
Parnaud G. Peiffer G. Tache S. Corpet DE.
Institution
Laboratoire Securite des Aliments, Institut National de la Recherche
Agronomique, Ecole Nationale Veterinaire, Toulouse, France.
Title
Effect of meat (beef,
chicken, and bacon) on rat colon carcinogenesis.
Source
Nutrition & Cancer. 32(3):165-73, 1998.
Abstract
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.
Additional comment by the poster:
Moral of the story: drink lots of water!