Orphan crops are those crops that did not receive the same attention of the research community as in the case of staples such as wheat, maize, or rice despite their regional and nutritional importance. A relatively recent trend has been promoting their research to improve their productivity and resilience to environmental shocks. However, their impact on consumers’ nutrition has been analysed only considering the crops individually and not in the context of the diet. This is important because an increase in the consumption of one product may trigger changes in the other products that conform to the diet. The purpose of this paper is to assess the potential impact, in terms of food choices and nutrition, of increasing the consumption of orphan crops (represented by millet) in the Kenyan diet. This is carried out using a microeconomic-based methodology, which augments the original consumer problem with a constraint regarding the amount of the orphan crop on the diet. To compute the required elasticities for the method, three demand systems—i.e., for rural, less affluent urban, more affluent urban households—were estimated using the 2015–16 Kenyan Integrated Household Survey and the two-step approach to address the zero consumption for some food categories; the second step was modelled using the Linquad demand model. The results indicate that although the orphan crops have the capacity to improve some of the nutrients (e.g., vitamins and minerals), in net terms, as measured by the aggregated nutritional indicator the improvement is somewhat limited, the improvements occur in the rural and the less affluent population.