Specialized diet linked to reduced cancer risk

John Murphy, MDLinx | November 14, 2018

A specific cancer-prevention diet that emphasizes more vegetables and physical activity, and less red meat and alcohol, reduced overall cancer risk as well as the risk for several types of cancer, according to investigators in a study involving more than 41,000 adults published in Cancer Research.

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Go easy on red meat and alcohol, according to researchers. A diet that instead emphasizes vegetables, fruits, beans, whole grains, and increased activity was linked to lower cancer risk.

The cancer-prevention diet, advocated by the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR), recommends plant-based, high-fiber foods that include whole grains, vegetables, fruit, and legumes. The recommendations also encourage physical activity and discourage fast foods, red and processed meats, sugar-sweetened drinks, and alcohol.

In addition to the WCRF/AICR diet, the researchers evaluated three other nutritional/dietary scoring systems: the Alternate Healthy Eating Index, the French Nutrition and Health Program-Guidelines Score, and the MEDI-LITE score, which measures adherence to a Mediterranean diet.

All four diets were linked with cancer risk reductions, but the WCRF/AICR recommendations had the strongest association with reduced risks for overall cancer, breast cancer, and prostate cancer.

“Results of the sensitivity analyses suggest that these strong and consistent associations were not driven by one specific component, but rather by a synergistic contribution of the different components of the score,” wrote senior author Mathilde Touvier, PhD, MPH, MSc, director, Nutritional Epidemiology Research Team, University of Paris 13, Bobigny, France, and coauthors.

Decrease in cancer risk

The study included 41,543 participants from the NutriNet-Santé cohort in France. Participants were aged 40 years and older and never had a cancer diagnosis. Every 6 months, participants completed online dietary assessments that recorded all foods and beverages they consumed in a 24-hour period. From these, the researchers used a point system to calculate the participants’ adherence to each of the four nutritional scores—a higher value corresponded to a better fit with the corresponding recommendations.

During the study (May 2009 to January 1, 2017), 1,489 incident cancer cases were diagnosed among all participants, including 488 breast cancers, 222 prostate cancers, and 118 colorectal cancers. The researchers used multivariable Cox proportional hazard models to characterize the associations of each nutritional score with cancer risk. They found that a 1-point increase in the WCRF/AICR score was associated with a 12% decrease in overall cancer risk, a 14% decrease in breast cancer risk, and a 12% decrease in prostate cancer risk.

Although the three other diets also led to reduced cancer risk when participants adhered to them, the WCRF/AICR recommendations had greater statistical strength and better predictive performance, the researchers noted.

“Among all risk factors for cancer (besides tobacco), nutrition and physical activity are modifiable lifestyle factors which can contribute to cancer risk,” Dr. Touvier said of these elements in the WCRF/AICR recommendations.

“This emphasizes the role of an overall healthy lifestyle—nutrition and physical activity and alcohol avoidance—in cancer prevention,” said corresponding author Bernard Srour, PharmD, MPH, doctoral researcher in nutritional epidemiology, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, Nutritional Epidemiology Research Team, University of Paris 13. “It is, therefore, important to keep in mind that every lifestyle factor counts, and it is never too late to adopt a healthy lifestyle.”

Alcohol and cancer

The findings from this study support recent research that points to alcohol as a risk factor for many cancer types. By design, the WCRF/AICR score classified alcohol consumption as a detriment, while the other scores were less strict about alcohol intake, the authors noted.

“In its last report, the WCRF stated that there is now strong, convincing evidence that alcohol consumption increases the risks of oropharyngeal, esophagus, liver, colorectal, and postmenopausal breast cancers,” Dr. Touvier said, adding that alcohol intake may be linked to stomach and premenopausal breast cancers, as well.

The study’s main limitation was that, because it was a volunteer study, it overrepresented women, people with health-conscious behaviors, and those with higher socioeconomic and educational levels compared with the general population. As such, unhealthy behaviors may have been underrepresented, so the associations of healthy diets with cancer prevention may actually be stronger than the findings indicated.

This study was funded by the French Ministry of Health, the French Agency for Public Health, the Ile-de-France region, the French National Institute of Health and Medical Research, the French National Institute for Agricultural Research, the Conservatoire National des Arts et Métiers, University of Paris 13, Cancéropôle Ile-de-France, and the French National Cancer Institute.

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