The benefits of a Mediterranean diet are well known when it comes to colorectal protection, but it’s hard to know specifically what elements of the diet are the healthiest. Now a new study, presented by Fliss Isakov et al at the ESMO 19th World Congress on Gastrointestinal Cancer, suggests that increasing consumption of fish and fruit and reducing soft drink consumption are the three most important components (Abstract O-023).
“We found that each one of these three choices was associated with a little more than 30% reduced odds of a person having an advanced, precancerous colorectal lesion, compared to people who did not eat any of the MD components. Among people who made all three healthy choices, the benefit was compounded to almost 86% reduced odds,” said Naomi Fliss Isakov, PhD, of Tel-Aviv Medical Center.
Study Background & Details
Colorectal cancer develops from intestinal polyps and has been linked to a low-fiber diet heavy on red meat, alcohol, and high-calorie foods, said Dr. Fliss Isakov.
While the Mediterranean diet has been associated with lower rates of colorectal cancer, the definition of what elements in the diet are the most beneficial has not always been clear.
Using dietary questionnaires from 808 individuals who were undergoing screening or diagnostic colonoscopies, the research team was able to dig down to look at the fine details of their daily meals.
All subjects were between 40 and 70 years old, without high risk of colorectal cancer, and answered a food frequency questionnaire.
Adherence to the Mediterranean diet components was defined as consumption levels above the group median for fruits, vegetables and legumes, nuts and seeds, whole grains, and fish and poultry; a high ratio of monounsaturated to saturated fatty acids; as well as consumption below the median of red meat, alcohol, and soft drinks.
The investigators found that compared to subjects with clear colonoscopies, those who had advanced polyps reported fewer components of the Mediterranean diet (a mean of 1.9 vs 4.5 components). Yet even consumption of two to three components of the diet, compared to none, was associated with half the odds of advanced polyps.
Odds were reduced in a dose response manner with additional Mediterranean diet components—meaning that the more Mediterranean diet components people followed, the lower their odds of having advanced colorectal polyps.
After adjusting to account for other colorectal cancer risk factors, including other dietary components, the researchers narrowed in on high fish and fruit and low soft drink consumption as the best combination for reduced odds of advanced colorectal polyps.
The next step will be to see whether the Mediterranean diet is linked to lower risk of colorectal cancer in higher-risk groups, Dr. Fliss Isakov concluded.
Commenting on the study, ESMO spokesperson Dirk Arnold, MD, PhD, from Instituto CUF de Oncologia in Lisbon, Portugal, said, “This large population-based cohort-control study impressively confirms the hypothesis of an association of colorectal polyps with diets and other lifestyle factors. This stands in line with other very recent findings on nutritive effects, such as the potential protective effects of nut consumption and vitamin D supplementation which have been shown earlier this year. However, it remains to be seen whether these results are associated with reduced mortality, and it is also unclear if and when a dietary change would be beneficial. Despite this lack of information, it makes sense to consider this diet for other health-related reasons also.”
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.