Adherence to the South African food based dietary guidelines may reduce breast cancer risk in black South African women: the South African Breast Cancer (SABC) study

Abstract

Objective: To determine the level of adherence, and to assess the association between higher adherence to the South African Food Based Dietary Guidelines (SAFBDGs) and breast cancer risk. Design: Population-based, case-control study (the South African Breast Cancer study), matched on age and demographic settings. Validated questionnaires were used to collect dietary and epidemiological data. To assess adherence to the SAFBDGs, a 9-point adherence score (out of 11 guidelines) was developed, using suggested adherence cut-points for scoring each recommendation (0 and 1). When the association between higher adherence to the SAFBDGs and breast cancer risk were assessed, data driven tertiles among controls were used as cut-points for scoring each recommendation (0, 0.5 and 1). Odds ratios and 95% confidence intervals were estimated using multivariate logistic regression models. Setting: Soweto, South Africa Population: Black urban women, 396 breast cancer cases and 396 controls. Results: After adjusting for potential confounders, higher adherence (>5.0) to the SAFBDGs vs. lower adherence (<3.5), was statistically significantly inversely associated with breast cancer risk overall (OR=0.56, 95%CI:0.38-0.85), among postmenopausal women (OR=0.64, 95%CI:0.40-0.97) as well as for oestrogen positive breast cancers (OR=0.51, 95%CI:0.32-0.89). Only 32.3% of cases and 39.1% of controls adhered to at least half (a score >4.5) of the SAFBDGs. Conclusions: Higher adherence to the SAFBDGs may reduce breast cancer risk in this population. The concerning low levels of adherence to the SAFBDGs emphasize the need for education campaigns and to create healthy food environments in South Africa to increase adherence to the SAFBDGs.