by Island RDN: Ayla Shaw MS, Registered Dietitian Nutritionist Dissecting the Relationship between Dietary Fiber Intake and Cancer Risk by Island RDN: Ayla Shaw MS, Registered Dietitian Nutritionist

Dissecting the Relationship between Dietary Fiber Intake and Cancer Risk The Gut Microbiome Fiber & Cancer Prevention

What is Dietary Fiber?

Dietary Fiber Indigestible Carbohydrate Plant-foods Beans and Legumes Fruits Vegetables Whole grains RDA: 25-30 grams per day

Dietary Fiber Soluble Insoluble Draws water into GI tract Loosens stools Fruits, Vegetables, Grains Products with added fiber Inulin Chicory Root Absorbs water Adds bulk to stool Binds Cholesterol Beta-Glucans

Average Dietary Fiber Intake between Countries 1. Mertens, Elly, et al. “Geographic and Socioeconomic Diversity of Food and Nutrient Intakes: A Comparison of Four European Countries.” European Journal of Nutrition, Mar. 2018, pp. 1–19. link.springer.com, doi:10.1007/s00394-018-1673-6. 2. McGill, Carla R., et al. “Ten-Year Trends in Fiber and Whole Grain Intakes and Food Sources for the United States Population: National Health and Nutrition Examination Survey 2001–2010.” Nutrients, vol. 7, no. 2, Feb. 2015, pp. 1119–30. PubMed Central, doi:10.3390/nu7021119.

The Gut Microbiome

The Gut Microbiome Microbes 30 trillion bacterial cells Funji Viruses 30 trillion bacterial cells Every person’s microbiome is slightly different Fingerprint Sender R, Fuchs S, Milo R. Revised Estimates for the Number of Human and Bacteria Cells in the Body. PLoS Biol. 2016 Aug 19;14(8):e1002533.

What’s the difference? Prebiotic Probiotic Indigestible fiber Provides energy and nutrients to probiotics Beneficial Microbes Living organism that use prebiotics for fuel

Altered gut bacteria have been linked to several diseases Inflammatory bowel disease Irritable bowel syndrome Obesity Type 2 diabetes Cancer https://www.cancerquest.org/cancer-biology/microbiome?gclid=CjwKCAjwkYDbBRB6EiwAR0T_-l2sxeZ5WnoEXMQjzs-8erZepLHhPbk_lKU-I_fh6rLrMzKu08688BoCFekQAvD_BwE#footnote2_uxp45jg

Fiber and Cancer Risk

Fruit, Vegetable, and Fiber Intake in Relation to Cancer Risk: Findings from the European Prospective Investigation into Cancer and Nutrition (EPIC) EPIC STUDY Over 500,000 participants in 10 Countries Colorectal, Liver, and Breast Cancer Risk inversely associated with fiber intake Bradbury, Kathryn E., et al. “Fruit, Vegetable, and Fiber Intake in Relation to Cancer Risk: Findings from the European Prospective Investigation into Cancer and Nutrition (EPIC).” The American Journal of Clinical Nutrition, vol. 100 Suppl 1, July 2014, pp. 394S-8S. PubMed, doi:10.3945/ajcn.113.071357.

Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks Mini-review assesses dietary pattern versus individual nutrients Positive relationships between fiber and health gut microbiome Supports recommendations of high fiber diet along with limited consumption of red meat and alcohol Tuan, Juan, and Ying-Xuan Chen. “Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks.” Gastrointestinal Tumors, vol. 3, no. 1, Sept. 2016, pp. 17–24. PubMed, doi:10.1159/000442831.

Dietary Fiber for the Prevention of Recurrent Colorectal Adenomas and Carcinomas Meta-analysis of seven studies with 4798 participants Purpose: Assess the effect of dietary fiber on the recurrence of colorectal cancer Results found lack of evidence to suggest that increased dietary fiber intake will reduce the risk of recurrence Yao, Yibo, et al. “Dietary Fibre for the Prevention of Recurrent Colorectal Adenomas and Carcinomas.” The Cochrane Database of Systematic Reviews, vol. 1, 08 2017, p. CD003430. PubMed, doi:10.1002/14651858.CD003430.pub2.

Dietary Fiber Intake in Young Adults and Breast Cancer Risk 90,534 participants for 20 years 44,263 participants for 10+ years Early adulthood total dietary fiber intake was associated with significantly lower breast cancer risk Farvid, Maryam S., et al. “Dietary Fiber Intake in Young Adults and Breast Cancer Risk.” Pediatrics, vol. 137, no. 3, Mar. 2016, p. e20151226. PubMed, doi:10.1542/peds.2015-1226.

Dietary Fiber Intake and Risk of Breast Cancer: A Systematic Review and Meta-analysis of Epidemiological Studies Review of twenty-four epidemiologic studies Population-based studies across multiple countries Higher dietary fiber reduced risk of breast cancer Particularly in postmenopausal women Chen, Sumei, et al. “Dietary Fibre Intake and Risk of Breast Cancer: A Systematic Review and Meta-Analysis of Epidemiological Studies.” Oncotarget, vol. 7, no. 49, Dec. 2016, pp. 80980–89. PubMed, doi:10.18632/oncotarget.13140.

Intake of Bean Fiber, Beans, and Grains and Reduced Risk of Hormone Receptor-Negative Breast Cancer: The San Francisco Bay Area Breast Cancer Study. ER‐PR breast cancer An aggressive subtype Few risk factors have been identified Analyzed food frequency data from 2135 breast cancer cases High intake of bean fiber & fiber‐rich foods may lower the risk of ER-PR Sangaramoorthy, Meera, et al. “Intake of Bean Fiber, Beans, and Grains and Reduced Risk of Hormone Receptor-Negative Breast Cancer: The San Francisco Bay Area Breast Cancer Study.” Cancer Medicine, vol. 7, no. 5, May 2018, pp. 2131–44. PubMed, doi:10.1002/cam4.1423.

Dietary Fiber and Other Cancers Pancreatic Cancer Better diet quality is associated with reduced risk Endometrial Cancer Inconlusive Head and Neck Cancer Greater intake of fiber may lower risk. Zheng, Jiali, et al. “Dietary Patterns and Risk of Pancreatic Cancer: A Systematic Review.” Nutrition Reviews, vol. 75, no. 11, Nov. 2017, pp. 883–908. PubMed, doi:10.1093/nutrit/nux038. Chen, Kangning, et al. “Dietary Fiber Intake and Endometrial Cancer Risk: A Systematic Review and Meta-Analysis.” Nutrients, vol. 10, no. 7, July 2018. PubMed, doi:10.3390/nu10070945. Kawakita, Daisuke, et al. “Dietary Fiber Intake and Head and Neck Cancer Risk: A Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium.” International Journal of Cancer, vol. 141, no. 9, 01 2017, pp. 1811–21. PubMed, doi:10.1002/ijc.30886.

Conclusion Single nutrient vs diet pattern Disease Risk vs Cause-and-effect Objective methods for measuring intake More RCT needed into “Mediterranean-style” diet

QUESTIONS?