Sticking to a Mediterranean diet reduces the risk of colorectal cancer, according to recent research conducted in Italy. The combined analysis of three previous studies showed that diet could lower the risk by as much as 50%, confirming previous findings.  

Certain foods and nutrients are known to affect the risk of colorectal cancer, but as foods are not eaten in isolation, the effect of diet as a whole is likely to be more relevant. Previous studies have suggested that a Mediterranean diet lowers the risk of several types of cancer, including colorectal cancer, but the impact in specific countries is unclear. This led Valentina Rosato from the Università degli Studi di Milano and colleagues to assess the effects of a Mediterranean diet on the risk of colorectal cancer in Italy. 

Rosato and colleagues analyzed data from three previous studies conducted in Italy, which included more than 10,500 people. For each participant, a Mediterranean diet score between 0 and 9 was calculated according to their adherence to the diet, defined as frequent consumption of vegetables, legumes, fruit, nuts, cereals, fish and olive oil, modest intake of wine, low-to-moderate consumption of dairy products, and low consumption of meat. An individual’s score was a reflection of whether their intake of nine dietary components in the preceding two years was above or below the average for participants who did not develop colorectal cancer. 

The researchers found that people who scored highest for overall adherence to the diet were half as likely to develop colorectal cancer compared with people who scored the lowest on adherence, suggesting a clear benefit of the diet. They also found that the effects on risk differed between each of the dietary components.  

The risk was lowered by a high intake of vegetables, legumes, fruit, nuts and fish; a high ratio of monounsaturated fats to saturated fats; and a low intake of meat. By contrast, the risk was increased by a high intake of cereals and potatoes, and a low intake of milk and dairy products. Alcohol intake had no effect. 

The relationship between diet and colorectal cancer was consistent regardless of age, sex, level of education, body mass index, levels of physical activity, total energy intake and history of intestinal cancer. The authors say that differences between countries and experimental design make comparisons between studies difficult, but the new work confirms previous findings in studies conducted in Italy.

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