To examine the prevalence and nutrient composition of menu offerings targeted to customers with dietary restrictions at US fast casual and full-service chain restaurants.

We used 2018 data from MenuStat, a database of nutrient information for menu items at large US chain restaurants. Five alternative diets were examined: gluten-free, low-calorie, low-carbohydrate, low-fat and vegetarian. Diet offerings were identified by searching MenuStat item descriptions and reviewing online menus. For each diet, we reported counts and proportions. We used bootstrapped multilevel models to examine differences in predicted mean kilojoules, saturated fat, Na and sugars between diet and non-diet menu items.

Forty-five US fast casual and full-service chain restaurants in 2018 (including 6419 items in initial analytic sample across small plates, salads and main dishes).

None.

The most prevalent diets were gluten-free (n 631, 9·8 % of menu items), low-calorie (n 306, 4·8 %) and vegetarian (n 230, 3·6 %). Compared with non-diet counterparts, low-calorie main dishes had significantly lower levels of all nutrients examined and vegetarian main dishes had significantly lower levels of all nutrients except saturated fat. Gluten-free small plates had significantly fewer kilojoules, grams of saturated fat and milligrams of Na compared with non-diet small plates.

A small proportion of fast casual and full-service restaurant menus are targeted towards customers with dietary restrictions. Compared with non-diet items, those classified as gluten-free, low-calorie or vegetarian generally have healthier nutrient profiles, but overall nutrient values are still too high for most menu items, regardless of dietary label.