Knowledge of lactose intolerance in Italian adults: a cross‑sectional assessment

To assess knowledge of lactose intolerance (LI) in Italian adults, identifying major knowledge gaps and factors associated with awareness.

A cross-sectional study was conducted between December 2024 and March 2025 among Italian adults (≥ 18 years). A newly developed 39-item online survey assessed knowledge of LI across four modules (definition, symptoms, diagnosis, and management). The knowledge score (range: - 39; +39) was calculated and participants were classified into three knowledge levels based on the tertile distribution of scores: "low knowledge", "intermediate knowledge", and "high knowledge"'. Univariable and multivariable ordinal logistic regression were carried out to investigate the association between respondents' characteristics and LI knowledge.

A total of 2025 respondents (85.4% female) were included in the analysis. The mean knowledge score was 15.4 ± 7.6. Overall, 36.6% of respondents showed low, 32.2% intermediate, and 31.2% high knowledge. Common misconceptions concern the belief that trace amounts of lactose (e.g., in lactose-free products or medications) can trigger symptoms and that a lactose-free diet does not pose a risk for nutritional deficiencies. Questions on unvalidated diagnostic methods elicited many "I don't know" responses, reflecting uncertainty about their reliability. Female gender, confirmed LI diagnosis, higher education and nutrition training were associated with higher knowledge, with the latter showing the strongest association (Odds Ratio 10.8, 95% CI: 8.30-14.2).

These findings highlight persistent misconceptions about LI and underscore the need for targeted educational strategies to improve public understanding and reduce inappropriate diagnostic and dietary practices.