To determine the best mobile applications available in the UK for logging nutrients consumed and find out what data sources they use to determine calories and, as available, other nutrients. Apps that fit into this category include Second Nature (https://www.secondnature.io/), MyFitnessPal, LifeSum, Better Me, Eat this much, Platejoy, and Suggestic. An ideal response would provide the links of one or more open-source data sets used by one or more dietary apps, with sources specific to the UK preferred.