In a recently published study in the European Journal of Clinical Nutrition, researchers collected and analyzed 12 studies that encompassed case-control experiments spanning over 17 years and aimed to clarify site-specific cancer outcomes of legume consumption.
Their multiple logistic regression models revealed that the odds ratios for legume consumption were below one for most of the studied cancer types, indicating a protective effect. However, legumes notably caused a statistically significant decrease in colorectal cancer.
An increase in legume consumption by just one serving per week was enough to reduce the risk of colorectal cancer by 13%. This study complements a growing body of research highlighting the clinical benefits of a healthy diet.
„Cancer“ is a term that encompasses a cohort of non-communicable diseases characterized by uncontrolled growth and division of abnormal cells leading to a malignant tumor. While combinations of genetic predisposition, environmental pollutants, lifestyles, and even some pathogen-transmitted diseases have been linked to triggering cancer („carcinogens“), researchers have attributed the alarming recent worldwide increase in cancer prevalence and mortality to a medically driven increase in human life expectancy, especially in affluent and developed countries.
Lifestyle and health behaviors have been observed to have a profound impact on cancer risk. The latest report from the World Cancer Research Fund International (WCRF) emphasizes the positive benefits of a healthy diet as a measure in cancer prevention and recommends consuming whole grains, fruits, vegetables, and legumes, totaling to 30g of dietary fiber per day. Legumes, plants from the Fabaceae family and their seeds (legumes), perfectly fit into this recommendation.
Many cultures around the world traditionally consume legumes and pulses as they represent a rich source of proteins, carbohydrates, fibers, and fatty acids. Recent research has also discovered the presence of several non-nutrient metabolites derived from legumes with interactive bioactive properties. Unfortunately, the potential anticarcinogenic benefits of these foods have not been scientifically confirmed, and the limited research in this area has not yielded conclusive results.
About the Study
The present study is based on a series (n = 12) of case-control experiments collectively aimed at elucidating the associations between legumes and cancer at multiple sites, including oral cavity, larynx, esophagus, stomach, breast, colorectal, endometrium, prostate, and ovarian and renal cancers.
These studies were conducted between 1991 and 2009 in centers in ten provinces in Italy and Switzerland. The original studies were designed with common methodology and outcome metrics, facilitating their comparisons and analyses in the current work.
The constituting studies included clinically (histologically) confirmed cancer patients with one of the aforementioned cancer types diagnosed within a year of voluntary (via an interview) participation (cases), with corresponding controls derived from patients admitted to hospitals with acute and non-neoplastic diseases unrelated to cancer. Since the original studies aimed to examine the associations between smoking, alcohol consumption, dietary habits, and cancer, it was known that controls did not smoke, drink, or make long-term changes to their diet.
The collected data included sociodemographic information, anthropometry, smoking habits, medical and health history, consumed beverages (including alcohol), and cancer familiarity. In particular, dietary habits were recorded using a Food Frequency Questionnaire (FFQ) that also included inquiries about legume consumption (frequency and portion size). Statistical analyses involved multiple logistic regression models used to generate odds ratios (ORs). ORs were calculated for different portion sizes and adjusted for covariates, including gender, age group, education, smoking, alcohol consumption, body mass index (BMI), chronic disease status, and physical activity.
„To assess whether a gender-specific difference exists in the association between legume consumption and cancer risk, we tested the interaction between gender and legume consumption in the regression models using the Likelihood-Ratio Test (LRT) between the model with and without the interaction term.“
Study Results and Conclusions
The overall sample size of all included studies was 10,482 cancer cases and an equal number of controls. Analyses revealed that 30–40% of the included participants (cases + controls) consumed at least one serving of legumes per week. The only exception was endometrial cancer. It was found that controls consumed more legumes than their respective cases.
Consumption of legumes was associated with ORs below one for all cancer types. While these results highlight the overall protective effect of legumes against cancer, colorectal cancer was the only type with a statistically significant OR. One serving of legumes per week resulted in an OR of 0.74 – individuals consuming at least one serving of legumes per week had a 26% lower risk of developing colorectal cancer in the future. Consuming two servings per week increased this probability to 35%, with each additional serving beyond two reducing the risk of colorectal cancer by 15%.
Adjusting for covariates (including gender) did not substantially alter these results. These findings underscore the importance of dietary habits in preventing chronic and potentially fatal diseases like cancer and confirm the inclusion of legumes as an effective intervention against colorectal cancer risk in both men and women, regardless of age.