Research
A high protein moderate carbohydrate diet fed at discrete meals reduces early progression of N-methyl-N-nitrosourea-induced breast tumorigenesis in rats
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* Corresponding author: Donald K Layman dlayman@illinois.edu
1 Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 905 S Goodwin Ave, Urbana, IL 61801, USA
2 Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, 117 Louise Freer Hall, 906 S Goodwin Ave, Urbana, IL 61801, USA
3 Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 S Goodwin Ave, Urbana, IL 61801, USA
4 Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, 2522 VMBSB, 2001 S Lincoln Ave, Urbana, IL 61801, USA
Nutrition & Metabolism 2010, 7:1 doi:10.1186/1743-7075-7-1
Published: 10 January 2010Abstract
Breast cancer is the most prevalent cancer in American women. Dietary factors are thought to have a strong influence on breast cancer incidence. This study utilized a meal-feeding protocol with female Sprague-Dawley rats to evaluate effects of two ratios of carbohydrate:protein on promotion and early progression of breast tissue carcinomas. Mammary tumors were induced by N-methyl-N-nitrosourea (MNU) at 52 d of age. Post-induction, animals were assigned to consume either a low protein high carbohydrate diet (LPHC; 15% and 60% of energy, respectively) or a high protein moderate carbohydrate diet (HPMC; 35% and 40% of energy, respectively) for 10 wk. Animals were fed 3 meals/day to mimic human absorption and metabolism patterns. The rate of palpable tumor incidence was reduced in HPMC relative to LPHC (12.9 ± 1.4%/wk vs. 18.2 ± 1.3%/wk). At 3 wk, post-prandial serum insulin was larger in the LPHC relative to HPMC (+136.4 ± 33.1 pmol/L vs. +38.1 ± 23.4 pmol/L), while at 10 wk there was a trend for post-prandial IGF-I to be increased in HPMC (P = 0.055). There were no differences in tumor latency, tumor surface area, or cumulative tumor mass between diet groups. The present study provides evidence that reducing the dietary carbohydrate:protein ratio attenuates the development of mammary tumors. These findings are consistent with reduced post-prandial insulin release potentially diminishing the proliferative environment required for breast cancer tumors to progress.