The Internet has become a major source of health and nutrition information. Little is known about the type of consulted websites (institutional v. non-institutional) and the tendency to discuss with a healthcare professional (HCP) the information found on the Internet. The aim of this cross-sectional study was to investigate health- and nutrition-related Internet use in a large French population-based study. Data were collected in 2013 using self-administered, web-based questionnaires from 42 113 participants of the NutriNet-Santé study (mean age=51·2 years, 76 % women). Unconditional multivariate logistic regression analyses and χ 2 tests were used for comparisons. In total, 85·1 % of the subjects used the Internet to search for health and/or nutrition information, and 23·6 % used the Internet to read or post messages on health/nutrition forums. Only 16·0 % discussed with a HCP the information found online. This proportion was lower in subjects with lower educational level (OR 0·77; 95 % CI 0·72, 0·82) and lower computer skills (OR 0·70; 95 % CI 0·65, 0·76). In total, 8038 health/nutrition websites were cited, with institutional websites representing only 12·9 % of that number. Only one institutional website was present in the top 10. Older subjects (OR 1·49; 95 % CI 1·28-1·74), those with lower educational level (OR 2·08; 95 % CI 1·75, 2·50) and lower nutritional knowledge (OR 1·33; 1·12, 1·59) were more likely to cite non-institutional websites. This large population-based study showed that institutional websites were infrequently accessed and that a few participants discussed the information found online with their HCP. This particular trend was especially visible among individuals who were more vulnerable regarding misleading information. This supports the need to increase awareness of high-quality websites providing reliable health/nutrition information.