Not All Dietary Fiber Lower Breast Cancer Risks [Video]

breast cancer

Eating more dietary fiber in daily meals could lower the risk of breast cancer in women, according to most scientific studies. One such study, which was a British review published in June 2012 issue of Annals of Oncology, analyzed 16 studies that examined the relationship between dietary fiber, fruits, and vegetables consumption and breast cancer risks. Researchers Dagfinn Aune and colleagues concluded that there is an inverse relationship between higher dietary fiber intake (about 25 or more grams) and breast cancer risks. However, in a more detailed review by Aune and colleagues that was published in Breast Cancer Research and Treatment a month later, the researchers found that not all dietary fiber consumption can lower breast cancer risks. The review showed that high fruit and high fruit and vegetable combination intake had very little risk reduction in breast cancer while higher vegetable intake had an opposite effect.

Another large French study supported the review was published in November 2013 of PLOS One. Researchers Mélanie Deschasaux and colleagues from the University of Paris suggested that not all sources of dietary fiber have the same cancer-fighting abilities among a sample population of almost 4,700 French women. Total dietary fiber intake did not correlate to lower breast cancer risk, and neither did consuming dietary fiber from legumes and fruits. On the contrary, those who ate more fiber from vegetable sources had a lowered risk of breast cancer. Even so, an increase of overall vegetable intake was not necessarily associated with lowered breast cancer risks.

The standard explanation of how dietary fiber can prevent cancer, in general, is that fiber add bulk in the digestive system, which helps to soften stool, shortening the amount of time that wastes travel through the colon. Since fecal matter contains carcinogens, dietary fiber promotes more bowel movements, reducing the chance of the intestines getting infected. However, a 1999 study published in The New England Journal of Medicine showed that there was very little significance in dietary fiber intake and colon cancer among almost 88,800 women. If dietary fiber does not necessarily reduce of risk of breast (or colon) cancer, then why does vegetable consumption score high in fighting cancer?

breast cancer

One possible answer is that not all vegetables, fruits, and whole grains contain equal amounts of antioxidants and other nutrients other than dietary fiber that lower the risks of breast cancer. A 2013 study among over 1,000 Chinese women showed that higher cruciferous vegetable consumption correlates to lower inflammation rates. The women who ate 1.5 cups of these veggies a day, who made up the top fifth of the sample population, had much less inflammatory indicators in their bloodstream than those who ate one cup or half a cup day, according to the study that was published in the Journal of the Academy of Nutrition and Dietetics. Cruciferous vegetables include broccoli, cabbage, baby bok choy, kale, Brussel sprouts, cauliflower, and similar dark green leafy vegetables.

What makes these vegetables special is that they contain cancer-fighting compounds, such as glucosinolates. These sulfurous compounds give cruciferous vegetables a slight bitter taste and sweet and sour smell. When these veggies are prepared, cooked, chewed, and digested, the glucosinolates are broken down and become active for the body to use, according to the National Cancer Institute. The cancer-fighting compounds help protect DNA damage, inhibit carcinogenic activities, induce apoptosis in cancer cells, and inhibit tumor cell migration.

breast cancer

Deschasaux and colleagues added that a high vegetable diet isn’t the sole solution to preventing or lowering the risk of breast cancer. Other factors that can influence the risk of getting cancer include smoking status and the amount and the quality of physical activities. This does not mean that fruits, whole grains, legumes, and non-cruciferous vegetables are not essential to maintaining optimal health since they also contain the necessary vitamins and minerals. Even though not all dietary fiber sources could lower the risk of breast cancer, they still have benefits in reducing the risks of other diseases and disorders, such as cardiovascular diseases, constipation, and high blood sugar. And how much more flavorful would any meal be without some color and sweetness to that bowl of salad?

By Nick Ng
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Annals of Oncology
Breast Cancer Research and Treatment
New England Journal of Medicine
Journal of the Academy of Nutrition and Dietetics
National Cancer Institute

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