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Study: Do women who eat a high fiber diet have a lower risk of breast cancer?

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This study is about:

The effect of a high-fiber diet on breast cancer risk for young adults.

Why is this study important?  

Researchers think that eating a high-fiber diet may reduce breast cancer risk by reducing levels in the body. 

Study findings:  

  1. A high-fiber diet during early adulthood (ages 27-44) was associated with lower risk of breast cancer.
  2. A high-fiber diet during adolescence was also associated with lower risk of breast cancer. 

What does this mean for me? 

This study indicates that eating dietary fiber during adolescence and early adulthood may reduce breast cancer risk. More research needs to be done to confirm this finding, because previous studies, which looked at fiber consumption in older women, do not agree with this finding. 

Regardless of its effect on breast cancer risk, incorporating fiber into the diet benefits a healthy lifestyle.  The American Cancer Society guidelines recommend eating foods that are high in fiber.  The Mayo Clinic notes that a diet high in fiber maintains bowel health, lowers cholesterol levels, controls blood sugar levels and helps people to achieve and/or maintain a healthy weight. 

Posted 3/18/16

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Farvid MS, Eliassen H, Cho E, et al. “Dietary Fiber Intake in Young Adults and Breast Cancer Risk.” Pediatrics. 137 (3), March 2016.   

Kushi, LH, Doyle, C, McCullough, M, et al., “American Cancer Society guidelines on nutrition and physical activity for cancer prevention,” CA: A Cancer Journal for Clinicians. 62 (1), p. 30-67, January/February 2012. 

Mayo Clinic Staff. “Dietary fiber:  Essential for a healthy diet.


FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

This article is relevant for:

Adolescent and young adult women

This article is also relevant for:


healthy people with average cancer risk

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Study background: 

Previous research found that dietary fiber does not affect breast cancer risk. However, most of these studies involved older women, and did not look at fiber consumption during adolescence or early adulthood, a critical time when exposure to factors that affect levels may affect breast cancer risk. 

In March 2016, Maryam Farvid and colleagues from the Harvard T.H. Chan School of Public Health and other institutions published a paper in the journal Pediatrics that examined the relationship between dietary fiber intake during adolescence and young adulthood and breast cancer risk later in life.

Researchers of this study wanted to know:

Whether dietary fiber can modify breast cancer risk.  

Population(s) looked at in the study: 

This study involved 90,534 premenopausal women between the ages of 27-44 who were part of the Nurses’ Health Study II cohort. To be a part of this study, the women could not have reported a previous cancer diagnosis (except non-melanoma skin cancer). The women answered questionnaires that asked about their diet from the point the study began, and were resurveyed every four years over a 20-year period.   

This group of women was also asked to complete another questionnaire about their diet during high school; 47,355 women returned this questionnaire. 

Study findings:  

  1. Consuming dietary fiber during early adulthood reduced breast cancer risk. Women who consumed the most fiber (about 25 grams per day) reduced their breast cancer risk the most compared to women who consumed the least fiber (less than 13 grams per day). The women who consumed the most fiber reduced their risk of getting breast cancer by 19%. 
  2. Consuming both soluble fiber (found in peas, beans and apples) and insoluble fiber (found in nuts and wheat bran) reduced breast cancer risk. Women who consumed high dietary soluble fiber had a 14% reduction in breast cancer risk, while women who consumed high dietary insoluble fiber had a 20% reduction in breast cancer risk.
  3. Total dietary fiber intake during adolescence was associated with a lower risk of breast cancer. Women who consumed the most fiber during adolescence had a 16% reduction in breast cancer risk. 


High-fiber foods also contain many other biologically active ingredients—researchers noted that they cannot exclude the possibility that some ingredients other than fiber contributed to lower breast cancer risk. Additionally, the study population was not a random sampling of women in the U.S.; all participants were registered nurses who are a part of the Nurses’ Health Study II cohort. All studies that look at these types of associations may be affected by other factors that researchers were unable to identify or control. The researchers in this study took into account many other factors that could affect breast cancer risk, but they were unable to definitively say that no other factors were involved.


This study suggests that consuming a diet that is high in fiber during adolescence and early adulthood may reduce breast cancer risk. However, more work needs to be done to confirm this finding. In the meantime, people should be sure to include dietary fiber in their diets regardless of the effect on breast cancer risk, as it is part of a healthy lifestyle. 

Expert Guidelines
Expert Guidelines

The American Cancer Society (ACS) guidelines on exercise, nutrition and weight for cancer prevention recommend the following: 

Diet and nutrition

  • Follow a healthy eating pattern, including:
    • foods that are high in nutrients in amounts that help you acheive and maintain a healthy body weight.
    • a variety of vegetables, fiber-rich legumes (beans and peas) and whole fruits in a variety of colors. Consume at least 2½ to 3 cups of vegetables and 1½ to 2 cups of fruit each day, depending on your calorie requirements. 
    • whole grains rather than refined grains. At least half of the grains you eat should be whole grains. 
  • A healthy eating pattern that limits or does not include:
    • red and processed meats.
    • sugar-sweetened beverages. 
    • highly processed foods and refined grain products.
  • It is best not to drink alcohol. People who choose to drink alcohol should:
    • have no more than 1 drink per day (women) or 2 drinks per day (men).


  • Exercise regularly.
    • Adults should get at least 150 minutes of moderate-intensity activity (equal to a brisk walk) or 75 minutes of vigorous activity (heart rate is increased, breathing is faster and you are sweating) each week, preferably spread throughout the week.
    • Physical activity has been shown to lower the risk of several types of cancer, including breast, endometrial, and colon. It also reduces the risk of other serious diseases including diabetes and heart disease.


  • Achieve and keep a healthy weight.
    • Being overweight or obese is a risk factor for many cancers, including breast, colon, endometrial and pancreatic. You can control your weight through regular exercise and healthy eating.

Other experts, including the following, also provide guidelines for exercise, nutrition and health: 

Updated: 07/19/2022

Questions To Ask Your Doctor
Questions To Ask Your Doctor

  • How much fiber should I incorporate into my diet?
  • What are good sources of dietary fiber?
  • What are other ways to reduce my breast cancer risk?
  • Can you refer me to a nutritionist?


Open Clinical Trials
Open Clinical Trials

The following are studies focused on nutrition and cancer prevention. 

Breast cancer

Colorectal cancer

Visit our Featured Research Page and Research Search and Enroll Tool to find additional studies enrolling people with or at high risk for cancer.

Updated: 05/29/2024

Find Experts
Find Experts

The following resources can help you locate a nutritionist near you or via telehealth

Finding nutritionists

  • You can find a registered dietician in your area through, the website for the Academy of Nutrition and Dietetics. Search for nutritionists by specialty, including "cancer," "weight management" and "heart health."

Related experts

  • The Livestrong at the YMCA program includes a free 12-week membership and fitness training with certified exercise experts. You can search by zip code for a program near you.  

Other ways to find experts

  • Register for the FORCE Message Boards and post on the Find a Specialist board to connect with other people who share your situation. 
  • The National Cancer Institute (NCI)-Designated Comprehensive Cancer Centers have specialists to manage the symptoms and side effects of cancer prevention or treatment. 
  • FORCE partners with Savor Health® to provide free, personalized, evidence-based nutrition support 24/7 and “on-demand" through their text-based Intelligent Nutrition Assistant (Ina®). You can subscribe here


Updated: 11/20/2023

Who covered this study?


A diet high in fiber may help protect against breast cancer This article rates 4.5 out of 5 stars

CBS News

Teen eating habits may help cut breast cancer risk This article rates 4.5 out of 5 stars

Huffington Post

High-fiber diet may help lower breast cancer risk This article rates 4.0 out of 5 stars

Health Day

Girls who eat more fiber may face lower breast cancer risk later: Study This article rates 4.0 out of 5 stars

Teen Vogue

This Is what you need to eat as a teen to help prevent breast cancer This article rates 4.0 out of 5 stars

How we rated the media

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