Olive oil, diet and colorectal cancer: an ecological study and a hypothesis

Abstract

Studyobjectives-Colorectal cancer (CRC) is a common cancer in many western countries and is probably caused in part by dietary factors. Southern European countries have lower incidence rates of CRC than many other western countries. It was postulated that, because olive oil is thought to influence bile salt secretion patterns in rats, it may influence the occurrence of CRC. The purpose of this study was to compare national levels of dietary factors, with particular reference to olive oil, with national diVerences in CRC incidence. Design-Ecological study using existing international databases. Incidence rates for CRC, food supply data, and olive oil consumption data were extracted from published sources, combined, and analysed to calculate the correlations between CRC and 10 dietary factors. Associations were then explored using stepwise multiple regression. Setting-28 countries from four continents. Main results-76% of the intercountry variation in CRC incidence rates was explained by three significant dietary factors-meat, fish and olive oil-in combination. Meat and fish were positively associated, and olive oil was negatively associated, with CRC incidence. Conclusion-Olive oil may have a protective eVect on the development of CRC. The proposed hypothesis is that olive oil may influence secondary bile acid patterns in the colon that, in turn, might influence polyamine metabolism in colonic enterocytes in ways that reduce progression from normal mucosa to adenoma and carcinoma. (J Epidemiol Community Health 2000;54:756-760) Colorectal cancer (CRC) is a common cancer in many western societies.1 2 The role of dietary factors in the development of CRC has long been recognised, and extensively studied, although the results are not clearcut. [1][2][3] CRC incidence is particularly high in countries with high meat consumption, for example, Australia and the United States. Mediterranean countries have lower rates than other western countries, which may rise on migration.1 2 It has been suggested that their low rates may be attributable to some extent to their diet, with their high consumption of fruit, vegetables and olive oil. There is some evidence that high concentrations of secondary bile acids are associated with increased risk of CRC.5 6 Reduced colonic transit time has been suggested as important in the aetiology of CRC.7 Dietary factors-including meat, fat, cereal, vegetables, fruit, milk and olive oilinfluence colonic transit time and the volume of secondary bile acids in the colon. We have carried out an ecological study in which the association of dietary factors with CRC, and their interrelations, were examined. Our study diVers from other ecological studies, such as Armstrong and Doll, 3 as we have included data on olive oil, which features significantly in the diet of southern European countries, 8 and has been suggested as an important regulator of cancer in these countries. 4 9-12 We also suggest a possible mechanism for the eVect of diet on CRC. Method DATA SOURCESThe data were extract...

A valid semiquantitative food frequency questionnaire to measure fish consumption

“…Increasingly more research is being conducted into the potential health benefits of eating fish, with evidence to suggest that dietary fish may play a protective role in diseases including cardiovascular disease, cancer, asthma and atopy (Caygill et al, 1996;Marckmann and Gronbaek 1999;Kobayashi et al, 1999;Stoneham et al, 2000;Kris-Etherton et al, 2002;Devereux and Seaton, 2003). The mechanism for this benefit has been proposed to be related to the content of omega-3 fatty acids in fish.…”

Scientific Opinion on Dietary Reference Values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol

“…For example, butter consumption is associated with an increased risk of lung cancer, whereas the consumption of foods containing animal fat has been associated with an increased risk of colorectal cancer (WCRF/AICR, 2007). Conversely, consumption of fish (WCRF/AICR, 2007;Geelen et al, 2007;Hall et al, 2008) and olive oil (Stoneham et al, 2000;Rouillier et al, 2005;Galeone et al, 2007) appear to decrease the risk of colorectal cancer. However, these associations cannot be attributed to specific fatty acids.…”

Modeling Techniques for Prediction of Safe Cooking Times of Mechanically Tenderized Beef Steaks

“…Stepwise regression can be performed using any of the following 3 procedures: forward selection, backward elimination, or both (Stoneham et al, 2000). However, in this study, backward elimination was used where all a-c Letters provide evidence of significant difference, where different letters represent statistical significance (P < 0.01) between ESCT values for a particular steak cut in the same column.…”

“…the prediction variables were initially included in the regression model equation, followed by the elimination of those that did not contribute to the accuracy of the prediction model. To further increase the accuracy of the model, the squared values of prediction variables were also included and those that did not contribute to the accuracy (P < 0.01) were eliminated (Stoneham et al, 2000). This resulted in a final model containing variables that significantly contributed to the prediction accuracy.…”