This article employs a nation-wide sample of supermarket scanner data to study product and brand competition in the Italian breakfast cereal market. An Almost Ideal Demand System (AIDS) modelled to include Distance Metrics (DMs) and consistent with the methodology proposed by Pinske, Slade and Brett (2002), is estimated to study demand responses, substitution patterns, own-price and cross-price elasticities. Estimation results indicate a certain level of brand loyalty and opposite attitudes towards product type. Elasticities point out the presence of patterns of substitution within products sharing the same brand and similar nutritional characteristics.