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Cutting carbs could thwart breast cancer

Kathleen Blanchard's picture
Two new studies show fewer carbohydrates in the diet may influence breast cancer

Just cutting carbohydrate intake a couple of days a week could help women lower their insulin levels, lose weight and curb their risk of breast cancer.

Researchers in South Manchester, England found cutting our carbs for just two days a week is better than some traditional dietary approaches for lowering the chances of breast cancer.

Obesity is a contributor to the disease, as is high insulin levels that accompanies too much weight.

Michelle Harvie, a research dietitian at the Genesis Prevention Center, at University Hospital in South Manchester, England, explains it takes a combination of reducing insulin in the body and losing weight to prevent breast cancer. Insulin is that a hormone secreted by the pancreas that keeps blood sugar levels in check,

Counting calories can lead to failure because it’s just too hard for most.

For their study, Harvie and colleagues asked 115 women to follow one of three diets:

  • 1500 calories a day consumed from a Mediterranean diet
  • A low-carbohydrate, 650 calorie diet two days a week
  • Low-carbohydrate diet with unlimited protein and healthy fats, also two days a week

The diets were followed for 4 months. The low carbohydrate diets were restricted to less than 50 grams of starch on the two days the women dieted.

"We know people find it difficult to diet seven days a week, so we tried the two-day approach, which seemed to help women adhere. Many got into the groove and ate better on their off days, too," said Harvie.

As expected, more women from the calorie restricted Mediterranean diet dropped out of the study; 88 women completed the pilot.

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Limiting carbohydrates two days a week was found to be better for weight loss than restricting calories.

The research also found lower levels of insulin and other biomarkers of breast cancer in women who ate fewer carbs two days a week. Insulin levels dropped 18 percent from eating less than 50 grams of carbohydrates two days a week, but was only 4 percent lower from calorie restriction.

Compared to eating a low calorie diet, women experienced 9 pounds of weight loss, versus 5 pounds in the group that restricted their calories to 1500 every day.

"It is interesting that the diet that only restricts carbohydrates but allows unlimited protein and fats is as effective as the calorie-restricted, low-carbohydrate diet," said Harvie, who hopes to find out more about how carbohydrates affect breast cancer.

The study is good news for women with a history of breast cancer who want to cut their risk factors for developing the disease. In the study, all of the women were overweight or obese and had family history of the disease.

Another recent study found women who are obese and have HER-2 positive breast cancer have poorer outcomes than normal weight women, adding significance to the finding. Researchers also know adiposity can fuel cancer growth and spread.

A recent study highlight from the 2011 CTRC-AACR San Antonio Breast Cancer Symposium,found women with higher intake of starchy foods after breast cancer treatment had a higher chance of recurrence.

Jennifer A. Emond, M.S., a public health doctoral student at the University of California, San Diego said, “Women who increased their starch intake over one year were at a much likelier risk for recurring.”

The findings came from an analysis of 2651 women who participated in the Women’s Healthy Eating and Living (WHEL) Dietary Intervention Trial.

Cutting carbohydrates just two days a week helped women lose body fat and reduce their insulin levels, to lower their risk for breast cancer. Taking in fewer carbs might also lower a woman's chance of breast cancer recurrence.



I am perplexed between these two. Which one is better. Is cutting carbs for 2 days better than calorie count? Thank you.
I would like to ask about carbs and breast cancer. Have there been more studies going deeper into the relationship of these two?
Yes, there are studies that go deeper. One is mentioned in the article re: breast cancer recurrence seems to be higher in women who increase their carbohydrates within a year after being treated. The researchers for the current study are continuing to explore how carbohydrates affect breast cancer. They are seeing the relationship but need to dig deeper for mechanism of how and if starch fuels cancer cells. So far, the theory is that carbs raise levels of free insulin, estrogens, and insulin-like growth factor-1 that might lead to the disease. A 2004 study titled "Carbohydrates and the risk of breast cancer among Mexican women' may be of interest to you. There is another, published April, 2011 titled" Low-Carbohydrate Diets, Dietary Approaches to Stop Hypertension-Style Diets, and the Risk of Postmenopausal Breast Cancer", published in the American Journal of Epidemiology. In May, 2008, another study found a link between the two - "Carbohydrate intake, glycemic index, glycemic load, and risk of postmenopausal breast cancer in a prospective study of French women" - published in the American Journal of Clinical Nutrition. For a detailed analysis of what might in the body, you might read "Protein-Bound Carbohydrates in Breast Cancer Liquid-Chromatographic Analysis for Mannose, Galactose, Fucose, and Sialic Acid in Serum". I hope this helps you explore more to see what has been found so far.
Yes, the study showed cutting carbs for two days a week was better than calorie counting.