Most people know that what we eat can affect our risk for cancer—notably, that animal foods are linked to a higher risk for cancer. But a new study suggests that plant-based foods are not created equal. Specifically, the quality and overall healthfulness of a plant-based diet may be key in breast cancer prevention.

Researchers found that a healthy plant-based diet lowered the risk for breast cancer 14% , while an unhealthy plant-based diet was linked to a 20% higher risk for breast cancer. For the study, researchers tracked over 65,000 postmenopausal women in France for over 20 years. The findings were consistent across all breast cancer subtypes, according to a press release from the American Society for Nutrition.

Which plant-based foods did the researchers consider healthy and high quality? Whole grains, nuts, legumes, fruits, vegetables, vegetable oils, tea or coffee. Those considered less healthy included fruit juices, potatoes, sugar-sweetened drinks, refined grains and desserts.

“These findings highlight that increasing the consumption of healthy plant foods and decreasing the consumption of less healthy plant foods and animal foods might help prevent all types of breast cancer,” Sanam Shah, the study’s lead author and a doctoral candidate at the Center for Research in Epidemiology and Population Health at Paris-Saclay University, Inserm, Gustave Roussy in France, said in the news release.

Past studies have examined the correlation between specific diets and cancer risk, including the Western diet, Mediterranean diet and vegetarian diet. Although results have been mixed, the data tend to show that eating less meat is associated with better health outcomes.

Shah noted that a plant-based is not necessarily a vegan or vegetarian one but rather a diet in which plant-based foods are consumed more often than animal-based foods.

“What is different about our study is that we could disentangle the effects of the quality of plant foods, which has not been the focus of previous studies on other dietary patterns,” said Shah. “By scoring healthy, unhealthy and animal-based foods, we comprehensively analyzed food intake by considering the ‘healthiness’ of food groups.”

Over the course of the study, 3,968  out of 65,574 postmenopausal women were diagnosed with breast cancer. Researchers observed significant differences in breast cancer rates between women with healthy diets versus women with unhealthy diets.

The findings suggest that a healthy plant-based diet is helpful for cancer prevention. However, further research is needed to see how these findings play out in diverse populations and to determine whether the relationship between diet and cancer rates is causal.

To learn more about diet and cancer, click “Diet Affects Cancer Growth and Treatment” and “Taste Rescue: Once chemo is over, your taste buds usually go back to normal.” For a collection of healthy recipes geared for the cancer patient, click #Recipe.