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Experts say a healthy diet is important after breast cancer treatment. Johner Images/Getty Images
  • A new study states that a healthy diet can reduce the risk of heart disease in people who have been treated for breast cancer.
  • Researchers reported that women who followed the DASH diet, or one closely resembling it, had the most significant risk reduction.
  • The type of chemotherapy a woman received also played a role in the risk factors.

Eating a healthy diet after a breast cancer diagnosis significantly reduces the risk of cardiovascular disease, according to a new study published in the journal JNCI Cancer Spectrum.

Researchers reviewed data from 3,415 women diagnosed with invasive breast cancer to examine associations between the quality of their diet and cardiovascular events.

The mean age of the participants was 60. The women were diagnosed with cancer between 2005 and 2013 and monitored through 2021.

The scientists used a scoring system based on five diet quality indices:

  • Dietary Approaches to Stop Hypertension (DASH) diet
  • Nutrition guidelines for cancer prevention from the American Cancer Society
  • Alternate Mediterranean dietary index
  • Healthy plant-based dietary index
  • The 2020 Healthy Eating Index from the U.S. Department of Agriculture

In their study, the researchers reported that women whose diets most closely followed the DASH diet at the time of their breast cancer diagnosis had a significantly reduced risk of heart disease.

The DASH diet emphasizes fruits, vegetables, whole grains, lean protein, and low-fat dairy. The diet also limits sodium, red meat, processed meat, and sugar-sweetened beverages.

“Not surprising,” said Dr. Parvin Peddi, a medical oncologist and director of Breast Medical Oncology for the Margie Petersen Breast Center at Providence Saint John’s Health Center and an associate professor of medical oncology at Saint John’s Cancer Institute in California. “Cardiovascular disease risk is dependent on diet as a factor in general. So not surprising that this also holds in breast cancer survivors and their risk.”

However, Peddi, who wasn’t involved in the research, told Medical News Today that this study does offer hope, saying, “the risk increase with breast cancer can at least in part be ameliorated by diet changes potentially.”

Researchers reported that when compared to women whose diets were least like the DASH diet, the women who followed the DASH diet had a:

The scientists also reported that higher consumption of low-fat dairy reduced the risk of cardiovascular disease-related death.

“I thought it was a very interesting study and well thought out, confirming suspicions that higher quality diet could be associated with lower cardiovascular disease risk in general, but specifically patients with breast cancer,” said Dr. Bhavana Pathak, a hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in California.

“It was helpful to learn about the role of dietary indices,” Pathak, who wasn’t involved in the research, told Medical News Today. “It was also interesting to look at the sub-analysis of which specific food types are associated with higher quartile disease, for instance, red meat versus nuts and legumes.”

The researchers also found the type of chemotherapy a woman received could change the relationship between diet and cardiovascular disease.

The researchers specifically pointed to women who received anthracycline chemotherapy and followed the DASH diet. They had a lower risk of cardiovascular disease than those who did not follow the diet.

“Medical professionals can use this information to provide tailored dietary recommendations to patients with breast cancer, promoting the adoption of evidence-based dietary interventions like the DASH diet,” said Isaac Ergas, PhD, MPH, a staff scientist at the Kaiser Permanente Northern California Division of Research and an author of the study.

“By educating patients on the importance of healthy food choices and providing ongoing support, clinicians can help individuals achieve and maintain optimal cardiovascular health,” Ergas told Medical News Today.

Peddi doesn’t think this topic is discussed with breast cancer survivors enough.

“Cardiovascular risk is not discussed as often as it should be,” she said. “Breast cancer treatment has improved a lot over the years, which means a lot more survivors. So, a discussion needs to be had with all breast cancer patients about all other risks, especially cardiovascular risk, to optimize their survival through all possible risk mitigation strategies.”

The researchers pointed out that cardiovascular disease is the number one cause of non-cancer-related deaths in breast cancer survivors.

They also noted that the higher risk of heart disease in this group of women could be from the cardiotoxic effects of the treatment, in addition to common risk factors for both breast cancer and cardiovascular disease, including aging, lack of exercise, and smoking.

When asked about possible reasons for the higher risk, Peddi said, “It’s hard to tease out but it could be due to chemotherapy, specific ones do affect the heart, effect on weight from anti-estrogen medications, and effect on cholesterol.”

“For example, anti-HER2 therapy for a specific type of breast cancer that overexpresses the protein HER2 is cardiotoxic,” she added. “Anthracyclines, a commonly used chemotherapy for triple-negative and some estrogen-positive breast cancers, are also cardiotoxic. Anti-estrogen medications are not directly cardiotoxic but can affect cholesterol levels and weight that can increase the risk of cardiovascular disease.”

The researchers concluded that implementing diets concordant with healthy dietary patterns may be beneficial for preventing heart disease for people who have been treated for breast cancer.

Additionally, they said, the DASH diet may provide the most benefit, particularly for people receiving cardiotoxic chemotherapies.

“The main takeaway of this study is the significant impact of the quality of one’s diet, particularly for diets that closely align with the DASH diet, on lowering the risk of cardiovascular disease among breast cancer survivors,” Ergas said. “This highlights the importance of implementing effective dietary interventions to promote long-term cardiovascular health in this high-risk population.”

Pathak points out a possible connection between the two diseases.

“I think cardiovascular disease and breast cancer are both diseases of women, and cardiovascular diseases are the leading killer of women,” she noted. “Both have lifestyle factors that can modify the risk of disease. We need to develop a more integrative approach to cancer care in the Western world to ameliorate these lifestyle risks that are multifactorial. Everything from socioeconomic access, health and nutritional literacy, body neutrality, and agency play a role in women deciding for themselves how to care for their health and as a result, the health of their families.”