Perceptions, attitudes and beliefs towards soya among healthy Asian women participating in a soya randomised controlled trial.

The soya-breast cancer risk relationship remains controversial in Asia due to limited and inconsistent research findings and is exacerbated by difficulties in recruiting and retaining participants in intervention trials. Understanding public perceptions towards soya is important for designing effective intervention trials. Here, we administered a close-ended, quantitative survey to healthy, peri- and post-menopausal Asian women in the Malaysian Soy and Mammographic Density (MiSo) Study to assess perception towards soya and explore motivators and barriers that affect study adherence using the Capability, Opportunity, Motivation and Belief (COM-B) Model and Theoretical Domains Framework (TDF). Of 118 participants, the majority reported the belief that soya promotes good health (Supplement = 85⋅7 %, Diet = 90⋅0 %, Control = 87⋅9 %). Most participants reported obtaining information about soya from the internet (Supplement = 61⋅0 %, Diet = 55⋅3 %, Control = 35⋅9 %), while health professionals were least reported (Supplement = 9⋅8 %, Diet = 7⋅9 %, Control = 5⋅1 %). Stratified analyses by study completion and adherence status yielded comparable findings. By the end of the study, dietary arm participants reported a strong belief that soya has no impact on their health (Supplement = 7⋅1 % v. Diet = 20⋅0 % v. Control = 0⋅0 %, P = 0⋅012). Motivation and opportunity strongly facilitated soya consumption, while psychological capability was the most common barrier to consumption though less evident among dietary arm participants. While most Asian women have a positive perception towards soya, theory-based intervention trials are warranted to understand the perception-study adherence relationship and to accurately inform the public of the health effects of soya.

A Randomized Controlled Trial of Soy Isoflavone Intake on Mammographic Density among Malaysian Women.

Soy intake is associated with lower breast cancer risk in observational studies concerning Asian women, however, no randomized controlled trials (RCT) have been conducted among Asian women living in Asia. This three-armed RCT assessed the effects of one-year soy isoflavone (ISF) intervention on mammographic density (MD) change among healthy peri- and postmenopausal Malaysian women. This study was registered at ClinicalTrials.gov (NCT03686098). Participants were randomized into the 100 mg/day ISF Supplement, 50 mg/day ISF Diet, or control arm, and assessed for change in absolute and relative dense area from digital mammograms conducted at enrolment and after 12 months, compared over time across study arms using Kruskal-Wallis tests. Out of 118 women enrolled, 91 women completed the intervention, while 27 women (23%) were lost in follow up. The ISF supplement arm participants observed a larger decline in dense area (−1.3 cm2), compared to the ISF diet (−0.5 cm2) and control arm (−0.8 cm2), though it was not statistically significant (p = 0.48). Notably, among women enrolled within 5 years of menopause; dense area declined by 6 cm2 in the ISF supplement arm, compared to <1.0 cm2 in the control arm (p = 0.13). This RCT demonstrates a possible causal association between soy ISF intake and MD, a biomarker of breast cancer risk, among Asian women around the time of menopause, but these findings require confirmation in a larger trial.