This study examines the influential factors posited by the Spiral of Silence Theory (SoS) in shaping people's perceptions of the overall public opinion towards food safety issues in China and their willingness to speak out. Two highly controversial issues, including genetically modified (GM) food and food additives, are examined. Using an online opt-in panel in China, we collected survey responses from a total of 1089 respondents, with a comparable age distribution to that of Chinese netizens, as indicated in the most recent census. Ordinary Least Squares (OLS) regressions were conducted to make statistical inferences about the proposed research questions and hypotheses. Findings suggest that perceived opinion incongruence, self-relevance, and self-influence significantly affected the extent to which people were willing to express their opinions on social media for the genetically modified food issue, but not the use of food additive issue. The study provides evidence of the silencing effect on publicly expressing opinions about the food safety related issues in China and clarifies the potential boundary conditions of the SoS mechanism in the context of Chinese social media where the majority of public opinions come into formation.
Keywords: food additives; genetically modified food; public opinion; spiral of silence.