As consumers increasingly use online supermarkets for grocery shopping, system designers can use digital nudges (e.g., food swap suggestions, shopping cart calorie counter) to promote healthier and more sustainable food choices in online supermarkets. We conducted a scoping review of 74 papers from computing, health, marketing, and psychology to investigate how system designers can use digital nudges in online grocery stores to influence food choices. Building on the stimulus-organism-response (SOR) model, this review presents a conceptual framework that summarizes 1) the different nudging types used in this context, 2) the influence on human processing and perception, and 3) the effectiveness of digital nudges for driving food choice at the individual, product selection, and shopping cart level.