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Cancer Survivors Overestimate Quality of Their Diets

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Most people who have been diagnosed with cancer think they eat a healthy diet, but a study found that their diets were generally poor.

The research was published in the June 2020 issue of the European Journal of Clinical Nutrition. Read the abstract of “Discrepancy between perceived diet quality and actual diet quality among US adult cancer survivors.”

Diet and breast cancer

Diet is thought to be partly responsible for about 30% to 40% of all cancers, but diet alone is unlikely to be the “cause” or “cure” of cancer. Although more research needs to be done on diet and breast cancer, findings suggest that physical activity, a healthy diet (particularly one low in fat and high in vegetables and fiber), and a healthy weight can help reduce the risk of a first breast cancer or the cancer coming back (recurrence) if you’ve been diagnosed.

Right now, we do know that being overweight is a risk factor for being diagnosed with a first-time breast cancer, as well as for the breast cancer recurring if you have been diagnosed. A healthy diet can help you get to and maintain a healthy weight.

About the study

To do the study, the researchers looked at information in the National Health and Nutrition Examination Survey. Each year, the National Health and Nutrition Examination Survey asks a nationally representative sample of about 5,000 people about:

  • what they eat
  • how they rate the quality of their diets
  • other health-related questions

The survey and the information collected are overseen and managed by the U.S. Centers for Disease Control and Prevention.

For this study, the researchers looked at dietary information from 2005 to 2014 from 2,361 cancer survivors and 23,114 people who had not been diagnosed with cancer. It’s not clear how many of the people in the study had been diagnosed with breast cancer.

To figure out the quality of the people’s diets, the researchers used what the people ate to give them a Healthy Eating Index score. The Healthy Eating Index, created by the U.S. Department of Agriculture (USDA), compares what people actually eat to the key recommendations in the USDA’s Dietary Guidelines for Americans. Healthy Eating Index scores range from 0 to 100. A score of 100 means that a person is eating a diet that closely follows the dietary recommendations and is considered a healthy diet.

The researchers then compared the quality of the diets of the cancer survivors to:

  • how the survivors rated their own diets
  • the diets of the people who had not been diagnosed with cancer
  • results of survivors’ diet quality from a similar study done 10 years ago

The results showed that:

  • Most (56%) of the cancer survivors thought the quality of their diet was better than it actually was.
  • The quality of cancer survivors’ diets had not improved in the past 10 years.
  • The quality of cancer survivors’ diets was generally poor, based on Healthy Eating Index scores. Still, cancer survivors’ diets were healthier than the diets of people who had not been diagnosed with cancer.
  • People who thought their diets were better than they actually were tended to have poorer diets than people who thought their diets were worse than they actually were.

People more likely to overestimate the quality of their diet:

  • were older
  • had higher incomes
  • had higher educational levels
  • were Hispanic

“Now that we know the difference in perceived and actual diet quality among survivors, we can design tailored interventions to improve diets in this population,” said lead researcher Hong Xue, Ph.D., associate professor of health administration and policy at George Mason University, in a statement. “We know from earlier studies that this can reduce the risk of cancer relapse and improve long-term outcomes.”

What this means for you

While the results of this study are somewhat troubling, it is important to know that this study relies on people accurately reporting what they eat. Sometimes people may forget what they eat or may be embarrassed to write down what they actually did eat.

If you’ve been diagnosed with breast cancer, we know that a healthy diet — along with exercise — can help you reach and maintain a healthy weight, which can help keep the risk of cancer recurrence as low as it can be. Eating a healthy diet can give you more energy and improve your quality of life. Eating well also can help you rebuild muscle strength and overcome treatment side effects, such as anemia or fatigue.

Some healthy diet choices you may want to consider:

  • eating a diet low in added sugar and processed foods
  • eating a diet rich in unprocessed, nutrient-dense foods (foods that have the most vitamins, minerals, and healthy compounds)
  • limiting or avoiding alcohol

For more information, visit the pages on Healthy Eating After Treatment.

To talk with others about maintaining a healthy diet after a breast cancer diagnosis, join the Discussion Board forum Recipe Swap for Healthy Living.

Written by: Jamie DePolo, senior editor

Reviewed by: Brian Wojciechowski, M.D., medical adviser

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