Study: Do women who eat a high fiber diet have a lower risk of breast cancer?
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STUDY AT A GLANCE
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 estrogen levels in the body.
- A high-fiber diet during early adulthood (ages 27-44) was associated with lower risk of breast cancer.
- 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.
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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:
Women under 45
Healthy people with average cancer risk
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IN DEPTH REVIEW OF RESEARCH
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 estrogen 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.
- 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%.
- 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.
- 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.
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 get to and stay at 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 such as 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:
- The Academy of Nutrition and Dietetics
- The United States Office of Disease Prevention and Health Promotion
- The American Institute for Cancer Research
- 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?
The following are studies focused on nutrition and cancer prevention.
- Energetics and Lifestyle in Inherited Syndromes (ELLIE’s Study). ELLIE’s Project is designed to look at factors, such as weight, Body Mass Index, metabolism, dietary habits and activity levels that may affect cancer risk in people with inherited mutations linked to cancer.
- NCT05094466: Parent and Family Obesity Intervention in Reducing Obesity Risk in Racial Ethnic Minority Families. This compares the effects of parent/caregiver-focused programs to family-focused programs in reducing obesity risk in racial ethnic minority families.
- NCT04374747: Fruit and Vegetable Intervention in Lactating Women to Reduce Breast Cancer Risk. This trial is for nursing mothers. This study will look to see if eating at least 8 to 10 daily servings of fruits and vegetables reduces breast cancer biomarkers.
- NCT03448003: Comprehensive Lifestyle Change To Prevent Breast Cancer. This trial looks at how well lifestyle changes work to prevent breast cancer. Premenopausal women 18 years and older with intact breast and ovaries are eligible.
- NCT04192071: Virtual Human Delivered Nutrition Module for Colorectal Cancer Prevention. This study will develop and test an interactive nutrition module for use with colorectal cancer screening to learn which messages and graphics promote understanding of cancer risk and promote screening.
Visit our Featured Research Page and Research Search and Enroll Tool to find additional studies enrolling people with, or at high risk for cancer.
Nutritionists and dieticians are experts in food and diet with a focus on helping people maintain or improve their health. Dieticians are experts who have received additional training and certification. You can find a registered dietician in your area through Eatright.org, the website for the Academy of Nutrition and Dietetics. You can search for nutritionists by specialty, including "cancer," "weight management" and "heart health."
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