Barcelona, Spain, 30 June 2017 – The benefits of a “Mediterranean diet” (MD) 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 today at the ESMO 19th World Congress on Gastrointestinal Cancer suggests loading up on fish and fruit, and cutting back on soft drinks are the three most important things.
“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, pre-cancerous 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 fromTel-Aviv Medical Center, in Tel Aviv, Israel.
Colorectal cancer (CRC) develops from intestinal polyps and has been linked to a low-fibre diet heavy on red meat, alcohol and high-calorie foods, said Fliss Isakov.
And 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 people 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 CRC, and answered a food frequency questionnaire.
Adherence to the MD components was defined as consumption levels above the group median for fruits, vegetables and legumes, nuts and seeds, whole grains, fish and poultry and a high ratio of monounsaturated to saturated fatty acids, as well 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 versus 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 MD components – meaning that the more MD components people adhered, the lower their odds of having advanced colorectal polyps.
After adjusting to account for other CRC risk factors, including other dietary components, the researchers narrowed in on high fish and fruit and low soft drinks as the best combo for reduced odds of advanced colorectal polyps.
The next step will be to see whether the MD is linked to lower risk of CRC in higher risk groups, she 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 life-style 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.”
Notes to Editors
- Abstract O-023 – ‘Mediterranean diet components are negatively associated with advanced colorectal polyps in a population-based case-control study’ will be presented by Dr. Fliss Isakov Naomi during ‘Session XIII: From Epidemiology to Prevention of GI Cancer’ on Friday, 30 June, 09:10 to 09:40 (CEST) in Auditorium A.
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Abstract for O-023
Mediterranean diet components are negatively associated with advanced colorectal polyps in a population-based case-control study
Fliss Isakov Naomi1, Zelver-Sagi Shira2, Webb Muriel2, Ivankovsky Dana3, Margalit Dana4, Kariv Revital1
1Tel-Aviv Medical Center, Tel Aviv, Israel, 2Tel-Aviv Medical Center, Tel Aviv, Irael, 3Haifa University, Haifa , Israel, 4University of Haifa, Haifa, Israel
Introduction: Colorectal cancer (CRC) is common and a leading cause of cancer-related death, which develops gradually from adenomatous and serrated polyps. Established dietary risk factors for CRC include high intake of red and processed meat, alcohol and calorie-dense foods, and low intake of plant-based foods. Adherence to the Mediterranean diet has been associated with lower risk of CRC in observational population studies. Its anti-neoplastic properties are attributed to a high fiber plant-based diet, low in calorie-dense foods, and high in fish over red meat intake. However, the association between the Mediterranean diet individual and combined components, and advanced colorectal polyps is still unclear. In this study, we aimed to evaluate the association between the Mediterranean diet individual and combined components, and advanced colorectal polyps (advanced adenoma and serrated adenoma) in a population based case-control study.
Methods: A case-control study among 808 consecutive subjects aged 40-70 years, undergoing screening or diagnostic colonoscopy. Exclusion included: colectomy, high risk for CRC, severe illness, and inability to complete the study questionnaires. All participants underwent anthropometric measurements, a medical and lifestyle interview and filled a detailed semi-quantitative food frequency questionnaire (FFQ), adapted to the Israeli population and to the needs of this study. Adherence to the Mediterranean diet components was defined as consumption of vegetables and legumes, fruits, nuts and seeds, whole grains, fish, ratio of monounsaturated (MUFA) to saturated fatty acids (SFA) and poultry above the sample median, and as consumption of red meat, alcohol, and soft drinks below the sample median.
Cases with advanced polyps were defined as: advanced adenoma (adenomas >10mm, with features of high-grade dysplasia or villous histology), >3 non-advanced adenomas or serrated adenomas and SA ≥ 10mm or with HGD. Cases were compared with controls which were free of past or present polyps
Results: The mean number of adhered Mediterranean diet components was significantly lower among cases with advanced polyps compared to controls (4.5±1.9 vs. 5.1±1.7, P=0.03), and was significantly associated with lower odds of advanced polyps in multivariate analysis (OR=0.81, 0.73-0.90). Adherence to 1 to 4, and 5 to 10 Mediterranean diet components were negatively associated with advanced colorectal polyps compared to none (OR=0.50, 95%CI 0.32-0.79, P=0.003 and OR=0.47, 95%CI 0.26-0.83, P=0.009, respectively). The components of the Mediterranean diet which were negatively associated with advanced polyps, with adjustment for potential confounders and to all other dietary components were: low intake of soft drinks (OR=0.65, 0.44-0.97), high intake of fruit (OR=0.66, 0.45-0.95) and high intake of fish (OR=0.62, 0.42-0.91). Combined adherence to all three components was significantly associated with lower odds of advanced colorectal polyps (OR=0.14, 0.04-0.41).
Conclusion: Adherence to the Mediterranean diet is negatively associated with advanced colorectal polyps. High intake of fish and fruit and low intake of soft drinks are associated with lower odds of advanced colorectal polyps, separately and even more so when combined. Prospective, large-scale studies may better clarify the relations between dietary pattern and colorectal neoplasia.