Abstract: A product substitution system may include a shopper device associated with a given shopper, and a product substitution server. The server may obtain descriptive purchased product data for purchased products from a retailer, and iteratively operate a natural language processing (NLP) algorithm to accept, as input thereto, the descriptive purchased product data, and generate, as output therefrom, a multi-dimensional representation of a relationship among the purchased products. The server may also, for each iteration, determine a product-to-product affinity based upon the multi-dimensional representation of the relationship, and determine a recommended substitute product for one of the products based upon the determined product-to-product affinity, and communicate the recommended substitute product to the shopper device. The server may also, for each iteration, obtain updated descriptive purchased product data for an updated plurality of purchased products from the retailer.