We carried out a case-control study, utilizing a food-based dietary inflammatory index to determine the inflammatory potential of diet and clarify its role in BC. This study provides evidence that more pro-inflammatory diet (higher tertile of the FDII) is statistically significant associated with BC risk.
Indeed, the incidence of BC has increased (19, 20). Therefore, finding prevention approaches is so important. Among the factors that can play a role in the development of BC, diet is recognized as a modifiable risk factor for BC. So that reported nearly one-third of BC can be prevented by dietary rectification (21). Various studies have been conducted on diverse aspects of diet and its association with BC. Several previous studies have been performed on the impact inflammatory potential of the diet by nutrient-based DII and breast cancer (22–24). In this regard, Haung et al., in a case-control study of a total of 867 cases and 824 controls proposed that higher DII scores, corresponding to more pro-inflammatory diets, were positively associated with BC risk among Chinese women (25). In a Swedish cohort of 49,258 women, among whom 1895 incident BC positive association were observed between DII and breast cancer, with somewhat stronger associations in postmenopausal women (26). Additionally, in another cohort of 34,700 women, aged 55–69 years showed positive associations between DII scores and BC risk (24). The outcomes of a recent meta-analysis including seven observational studies involving 319,993 participants suggested more pro-inflammatory diets (higher DII scores) are related with 25% increased BC incidence (27). In contrast, Tabung et al., in a large prospective investigation of pre-diagnosis dietary inflammatory potential in postmenopausal women observed a more pro-inflammatory diet was not associated with higher risk of BC incidence. However, there was a significantly higher risk of BC death with higher baseline DII scores (28). In a German population-based case-control study, 2887 postmenopausal BC patients aged 50–74 years and 5,512 healthy age-matched controls suggested no significant between the energy-adjusted-DII and postmenopausal BC (29). Likewise, Gardeazabal et al., among 10,713 middle-aged Spanish female university graduates from the SUN cohort observed no statistically significant association between a more pro-inflammatory diet and overall risk of BC (30). Contradictory results in association between DII and BC in various studies may be due to inconsistencies in breast cancer biology, differences in socio-demographic characteristic, ethnicity, study design type, or study population.
The outcomes of most researches supports that the inflammatory potential of diet is an influential factor in systemic inflammation. However, all of these investigates have centralized on the association between nutrient-based DII and BC. There is no previous study that examined the association of food-based DII and odds of BC. Both indicators estimate the inflammatory potential of the diet; however vary in notion and design. Studies based on nutrient-based DII provide valuable data, but the food-based DII score and other dietary patterns according to food groups are more practical for adherence to dietary recommendation to achieve optimal health, and are more relevant to dietary guidelines for health promotion and disease prevention.. Based on the findings of the present study, to reduce the incidence of BC, people are recommended to consume anti-inflammatory food groups including fruits, vegetables, fish, canned fish, poultry, olive, legumes and restrict the use of pro-inflammatory food groups including processed meat, organ meat, egg, snack, mayonnaise, salt, grains, high-fat dairy, boiled potato, oil and butter, coffee, pickles, sweet dessert and fried potato.
Several biological mechanisms may elucidate the higher BC incidence among women with higher pro-inflammatory diet consumption. A large body of existing literature reports the positive correlation between inflammatory potential of diet and cytokine levels including IL-6, CRP and TNF-α (31–34). High levels of several cytokines, including CRP, IL-1β, IL-6 and TNF-α, have been shown to play a substantial role in greater risk of BC (8, 35–37). Cytokines are involved in cell growth, angiogenesis, proliferation, metastasis and apoptosis prevention (5, 38–40). It has also been proposed that immunosuppressive properties and up-regulation of oncoproteins due to chronic inflammation may contribute to the development of BC (41, 42).