Women Infant and Children program participants' beliefs and consumption of soy milk: Application of the Theory of Planned Behavior

The purpose of this study was to determine if Theory of Planned Behavior (TPB) variables predict soy milk intake in a sample of WIC participants in 2 Illinois counties (n = 380). A cross-sectional survey was used, which examined soy foods intake, behavioral beliefs, subjective norms, motivation, and intention. Soy product intake was low at both sites, and many participants (40%) did not know that soy milk was WIC approved. Most (> 70%) wanted to comply with their health care providers, but didn't know their opinions about soy milk (50-66%). Intention was significantly correlated with intake (0.507, P ≤ 0.01; 0.308, P ≤ 0.05). Environmental beliefs (0.282 and 0.410, P ≤ 0.01) and expectancy beliefs (0.490 and 0.636, P ≤ 0.01) were correlated with intention. At site 1, 30% of the variance in intention to consume soy milk was explained by expectancy beliefs and subjective norm beliefs (P < 0.0001); at site 2, 40% of the variance in intention was explained by expectancy beliefs. The TPB variables of expectancy beliefs predicted intention to consume soy milk in WIC participants. Therefore, knowing more about the health benefits of soy and how to cook with soy milk would increase WIC participants' intention to consume soy milk. Positive messages about soy milk from health care providers could influence intake.