Exhaustive Overview of Dietary Plant Lectins: Prospective Importance in the Mediterranean Diet

Abstract

Stillmark reported in 1888 that castor bean extracts were able to agglutinate red blood cells from different species [1]. The seed extracts were found to contain haemagglutinating proteins, defined as agglutinins. Haemagglutinins are now known as lectins, a term proposed many years ago. Lectins are a very heterogeneous group of proteins of non-immune origin and have gone through several definition steps resulting in lesser strictness over the years. Some years ago, Van Damme defined lectins as: “carbohydrate-binding proteins possessing at least one non-catalytic domain, which bind reversibly to a specific mono- or oligosaccharide” [2]. The continuous discovery of new and diverse lectins with similarities found in several different classes of proteins seems to call for even less strict definitions in the future. Maybe the most accurate lectin definition would simply be: “proteins that specifically bind or cross-bind carbohydrates”. Lectins are becoming more and more interesting as components of our diet, and it is interesting to note that in the U.S. News and World Report of 2020 the Mediterranean diet has been named as the best overall healthy diet [3]. The diet is well-known for its high content of vegetables, fruits and nuts and whole grains. This review examines our current knowledge of its importance for the Mediterranean diet.