Breast cancer and plant-based diets: Unhealthy foods linked to 20% higher risk

  • Body-mass index and diet have both been linked to increased cancer risk, though the exact nature of the mechanism behind this is not well understood, and is assumed to be multifactorial.
  • New research has shown a diet rich in fruit, vegetables, whole grains, and nuts may reduce the risk of developing breast cancer in postmenopausal women.
  • The same study found that breast cancer risk may increase in postmenopausal women who eat an “unhealthy” diet rich in refined grains, fruit juices, potatoes, and processed products of plant origin.

The food we eat, what we drink, and our lifestyle influence our cancer risk. According to Cancer Research U.K., certain foods are directly linked to the risk of developing cancer but overall diet is more important, helping maintain a healthy weight.

However, there is strong evidenceTrusted Source that eating more whole grains and fiber reduces the risks of cancer, and that processed meat is “carcinogenic to humans”.

Vegan and vegetarian diets may, in particular, have health benefits as they have been associated with better health outcomes for type 2 diabetesTrusted Source and heart diseaseTrusted Source.

New research at Paris-Saclay University has studied the association between a plant-based diet and breast cancer risk among postmenopausal women.

The work was presented at the American Society for NutritionNutrition 2022 live online meeting held from June 14-16. Led by doctoral candidate Sanam Sha, the study investigated how the quality of plant foods—healthy and unhealthy—may be linked with different outcomes.


Researchers collected data from over 65 000 women from the Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l’Education Nationale study (E3N) for over two decades.

The researchers identified and classified the cases of breast cancer using receptor and histological subtypes. The patients self-reported their diets and the researchers scored them as healthful and unhealthful plant-based diets.

The researchers recorded nearly 4,000 cases of breast cancer during the study. The risk of breast cancer among the participants was reduced the more they adhered to a healthy plant-based diet, the results showed.

The researchers found that the women who regularly ate a healthy plant-based diet—even if it included animal-based foods—were 14% less likely to develop breast cancer. The results were applicable to all breast cancer subtypes.

This was compared to women who ate a more unhealthy plant-based diet, which included foods such as fruit juices, potatoes, and dessert. This group had a 20% higher risk of breast cancer, in comparison.

Plant-based vs. vegetarian

“Plant-based diets are often used interchangeably with vegetarian or vegan diets,” said Sha.

“However, a healthy plant-based diet comprises higher intakes of fruit, vegetables, whole grains, nuts, legumes, tea, and coffee. In contrast, the unhealthy plant-based diet comprises higher intakes of primarily processed/refined products of plant origin such as refined grains, fruit juices, sweets/desserts, and potatoes. In both instances, the diet still includes some animal-based foods,” she detailed to Medical News Today.

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