Healthy plant-based diet may reduce breast cancer risk
04 Jul 2022
bởiRoshini Claire Anthony
Adherence to a healthy plant-based diet was tied to a reduced risk of breast cancer, according to a French study presented at Nutrition 2022. In contrast, an unhealthy plant-based diet may be tied to increased breast cancer risk.
“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,” said lead author Dr Sanam Shah, a doctoral candidate at the Center for Research in Epidemiology and Population Health at Paris-Saclay University, Inserm, Gustave Roussy, France.
Study participants were 65,574 postmenopausal women (mean age 52.8 years) enrolled in the French E3N* cohort who were followed from 1993 to 2014. Adherence to plant-based diets, be it healthy or unhealthy, was assessed by means of self-reported dietary intake scores at baseline (1993) and during follow-up (2005). A plant-based diet index was used to categorize foods as healthy or unhealthy (healthy: whole grains, fruit, vegetables, nuts, legumes, vegetable oils, tea or coffee; unhealthy: fruit juices, refined grains, potatoes, sugar-sweetened beverages, sweets and desserts). Animal-based foods were inversely associated with both the healthy and unhealthy plant-based diet index.
Over a mean 21 years of follow-up, 3,968 incident cases of breast cancer were diagnosed.
Overall, the highest rate** of adherence to a healthy plant-based diet was associated with a 14-percent reduced risk of breast cancer compared with the lowest rate of adherence (hazard ratio [HR], 0.86, 95 percent confidence interval [CI], 0.77–0.95). [Nutrition 2022, abstract OR07-03-22]
The results were consistent regardless of oestrogen receptor (ER) status (HRs, 0.85 and 0.88 for ER+ and ER-, respectively; pheterogeneity=0.8) or progesterone receptor (PR) status (HRs, 0.87 and 0.84 for PR+ and PR-, respectively; pheterogeneity=0.76), as well as in patients who were ER+PR+ (HR, 0.86) and those who were ER-PR- (HR, 0.87; pheterogeneity=0.95). The results were also similar in patients with ductal or lobular histology (HRs, 0.84 and 0.79, respectively), though less evident among those with other histology (HR, 1.03; pheterogeneity=0.42).
Conversely, greatest adherence to an unhealthy plant-based diet was tied to a 20-percent increased risk of breast cancer compared with the lowest adherence (HR, 1.20, 95 percent CI, 1.08–1.33). This increased risk was evident in all subgroups assessed (HRs, 1.20 for both ER+ and ER- breast cancer; pheterogeneity=0.98; HRs, 1.18 and 1.24 for PR+ and PR- breast cancer, respectively; pheterogeneity=0.62; HRs, 1.17 and 1.19 for ER+PR+ and ER-PR- breast cancer, respectively; pheterogeneity=0.93; and HRs 1.17, 1.55, and 1.05 for ductal, lobular, and other histology, respectively; pheterogeneity=0.09).
The mechanisms behind the plant-based diet–breast cancer risk association have yet to be determined, said Shah. “However, it has been suggested that high fibre may lower cancer risk via anti-inflammatory and antioxidant effects.” Polyphenols may also play a role, she added.
“Breast cancer has long been known to be influenced by genetic predisposition and environmental, reproductive, and lifestyle factors,” noted Shah. “Among lifestyle factors, poor diet is one of the modifiable risk factors.”
She noted that the plant-based diets assessed in this study were not necessarily vegetarian or vegan diets, but focused primarily on foods of plant origin with small quantities derived from animal sources. “These dietary patterns are easier to adopt than the entire exclusion of animal foods.”
“[These] results support the importance of the quality of plant-based foods and consuming time-predominant diets with a balance of animal-based foods with regard to the primary prevention of breast cancer,” Shah concluded. She called for further research to confirm these findings and ascertain the mechanisms behind the plant-based diet–breast cancer risk association.