Vicia faba agglutinin (VFA) is isolated from fava beans and is purified by affinity chromatography. It is a glycoprotein with a molecular weight of 52,000, and is a tetramer composed of two dissimilar subunits. This lectin is a weak, non-specific hemagglutinin that has a carbohydrate specificity for mannose and glucose, and elutes with the sugar mannose. VFA is mitogenic for human and murine lymphocytes.

The lyophilized preparation of VFA forms insoluble aggregates between pH 5 and 10. All preparations of VFA contain various fragments and polymers of the two subunits. When stored at a pH lower than 5, the lectin does not form aggregates, which may be explained by the lectins reactivity with mannose.

VFA can increase morphological differentiation and thus diminish the malignant phenotype of colorectal cancer cells. VFA appears to be the only known non-toxic dietary lectin, other than ABL, with inhibitory effects on proliferation. This lectin and other mannose binding plant lectins may contribute to protection from colorectal cancer by vegetables through effects on tumor development.