Women consuming more fiber may reduce risk of breast cancer

Making it a daily habit choosing foods high in fiber appear to possibly lower the risk of breast cancer in women.  This news comes from a systematic review and meta-analysis of 20 prospective studies published in CANCER, a peer-reviewed journal of the American Cancer Society.

Breast cancer and women in 2020

Over the course of their lifetime, one in eight U.S. women (about 13%) will develop invasive breast cancer, according to the American Cancer Society. For 2020, an estimated 276,480 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 48,530 new cases of non-invasive (in situ) breast cancer.

Men, can also develop breast cancer, but at a much lower risk than women.  It is estimated that 2,620 new cases of men will be diagnosed with breast cancer in 2020, making a man’s lifetime risk of this disease about 1 in 883.

Besides skin cancer, breast cancer is the most commonly diagnosed cancer among American women with an estimated 30% of newly diagnosed cancers in women are breast cancer. For women in the U.S., breast cancer death rates are also higher than those for any other cancer, besides lung cancer.

Study findings

The study’s purpose was to find the potential relationship between fiber intake and breast cancer. To do so, the researchers reviewed all relevant prospective studies published through July 2019 that reported on the association between fiber consumption and breast cancer.

Results from this search revealed that women who had the highest consumption of fiber had an eight percent lower risk of developing breast cancer. Women, who chose foods containing soluble fiber, had an associated lower risk of breast cancer.  For premenopausal and postmenopausal women, the higher their total fiber intake was, the lower associated risk of them developing breast cancer.  

The majority of American women’s fiber sources (about 45%) come from whole grains and cereals. Vegetables are the next highest source of fiber for women at about 23% and the remaining comes from fruits, nuts, beans, and seeds. However, the study found that the source of fiber wasn’t as important as the amount consumed. This study does support the dietary guidelines for fiber recommended by the American Cancer Society.  The 2015-2020 Dietary Guidelines for Americans suggest women should aim for 25 grams of fiber daily.

Researchers with the study did point out that their findings did not directly show that dietary fiber reduces breast cancer risk.  A randomized clinical trial would be necessary in order to show a cause and effect.

Why fiber and what sources are best?

Most of us know we should eat more fiber but why?  Fiber is only found in foods of plant origin (no animal-based food contains fiber) and is a substance our body does not digest. It actually passes through the digestive tract, mostly intact, without being broken down like other foods. This means it creates bulk which aids in moving bowel movements and possible harmful carcinogens through the digestive tract.

People who lack dietary fiber, often experience irregularity, constipation, and sluggishness.  Other health benefits of fiber include reducing the incidence of heart disease, type 2 diabetes, diverticular disease, blood pressure, and improve weight loss by creating a feeling of fullness reducing calorie intake.

There are two kinds of fiber – soluble and insoluble. Soluble fiber softens with water creating a gel-like substance helping lower blood cholesterol and glucose levels. Insoluble fiber absorbs water adding bulk to the digestive tract and moves stools through quickly.

Foods rich in soluble fiber include oats, oat bran, peas, beans, apples, and citrus fruits. Foods rich in insoluble fiber include whole wheat flour, wheat bran, rye, cabbage, carrots, Brussels sprouts, and nuts.

Consuming a high-fiber diet has shown to help reduce various health conditions besides the possibility of breast cancer in women. These conditions include heart disease, diabetes, diverticular disease, constipation, and colon cancer.  Our digestive system relies on fiber for “sweeping up and out” particles and compounds that could potentially cause health issues in the small and large intestine.

For now, women should focus on fiber as one tool they can utilize to possibly lower their risk of breast cancer.

David B. Samadi, MD, Urologic Oncology Expert and Robotic Surgeon located at 485 Madison Avenue on the 21st floor, New York, NY – 212-365-5000.  Follow Dr. Samadi at www.samadimd.com,  www.prostatecancer911.com, and www.roboticoncology.com.