Cancer Letters

Cancer Letters

Volume 165, Issue 1, 10 April 2001, Pages 27-33
Cancer Letters

Whole almonds and almond fractions reduce aberrant crypt foci in a rat model of colon carcinogenesis

https://doi.org/10.1016/S0304-3835(01)00425-6Get rights and content

Abstract

Almonds and other nuts appear to confer health benefits despite their high fat content. To assess the effect of almonds on colon cancer, whole almond-, almond meal- or almond oil-containing diet effects on aberrant crypt foci (ACF) in azoxymethane-treated F344 male rats were investigated. Six-week-old male F344 rats were fed the various almond and control diets and given subcutaneous injections of azoxymethane (15 mg/kg body weight) twice 1 week apart. After 26 weeks animals were injected with bromodeoxyuridine 1 h prior to sacrifice, after which colons were evaluated for ACF and cell turnover (labeling index, LI). Whole almond ACF and LI were both significantly lower than wheat bran and cellulose diet groups (−30 and −40%, respectively), while almond meal and almond oil ACF and almond meal LI declines were only significant vs. cellulose (P<0.05). These results suggest that almond consumption may reduce colon cancer risk and does so via at least one almond lipid-associated component.

Introduction

Colon cancer is a leading cause of cancer deaths for both men and women in the US [1]. Population studies suggest that 90% of large bowel cancer deaths are diet-related and that high saturated fat and red meat intake increases colon cancer risk [2], [3], [4]. From these and other data, foods containing a significant percentage of calories from fat have been labeled as ‘unhealthy’. However, a growing number of studies have suggested that increased consumption of almonds and other nuts, high fat foods, in fact confer health benefits such as declines in heart disease [5], [6], [7], [8]. Moreover, increasing evidence suggests that the linkage between fat and colon cancer in particular [9], [10] as well as other cancers and diseases in general is complex. Specifically, while high fat (40% of energy) intake does produce a high level of colon cancer promotion, this relationship very much depends on the type of dietary fat [11], [12]. The specific effects of nuts with respect to colon cancer remain ill-defined and there appear to be no published animal studies that have directly examined the effect of almond or other nut consumption on colon cancer-associated endpoints. In response, we have undertaken a study to examine the effects of almond consumption on colon cancer markers in a chemically-induced animal model of colon carcinogenesis.

Section snippets

Animals

Male Fischer 344 rats, 5 weeks after birth, were purchased from Simonsen Laboratories (Gilroy, CA). They were housed individually with free access to chow for 2 weeks. After 2 weeks, animals were randomized into diet groups (N=10/group) and the assigned experimental diets were substituted for chow and fed for 26 weeks. Lighting in the room was maintained on a reverse 12 h (light 17:00–05:00 h) cycle. All animal procedures were approved by the Animal Care and Use Committee of the Western

Results

The final body weight and organ weights (liver and colon) of the various diet groups are shown in Table 2. All the diet groups readily consumed the diets offered and gained weight at similar rates (data not shown). There were modest but statistically significant diet effects on body weight (P<0.05) and liver weight (P<0.04) but the diet effect on colon weight did not achieve statistical significance. In the case of body weight, animals fed almond oil-containing diets were the heaviest and the

Discussion

The current study found that rats fed isocaloric, macronutrient-matched high fat, low fiber diets formulated using whole almonds, almond meal or almond oil showed large and statistically significant dietary treatment-related declines in ACF as well as colonic cell turnover. While the whole almond group showed statistically significant effects irregardless of the control group comparison employed, diets formulated with almond fractions showed statistically significant declines in either ACF

Acknowledgements

The authors would like to thank Drs B. Schneeman and W. Yokoyama for their helpful suggestions regarding the manuscript. The authors would further like to thank Dr Yokoyama and his coworkers for their advice and assistance with the animal housing and diet-related matters. This research was supported by a grant from the Almond Board of California.

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