Google, Baidu AI Overviews favor own platforms in health answers

A study by researchers Mingyue Zha and Ho-Chun Herbert Chang audited 1,920 health queries across 12 countries and 4 languages on Google and Baidu’s AI Overview systems, posted to arXiv in September 2026. Both engines showed “vertical integration,” routing users toward their own company’s platforms rather than a diverse set of primary health sources, and smaller, less-localized countries received fewer domestically sourced health references. Querying in a country’s native language instead of English increased locally sourced citations roughly 3.5- to 13.5-fold, and health disclaimers varied substantially by language and culture.