Cyanogenic glucosides
The seeds and leaves of lima bean contain cyanogenic glucosides (linamarin and phaseolunatin) and linamarase (the enzyme that turns cyanogenic glucosides into HCN). Cyanogenic potential varies with maturity, stage of development, genotype and cultivation conditions. Young leaves and seeds have higher HCN potential (Ballhorn et al., 2005) and cultivated varieties contain much lower cyanoglucosides than wild varieties (100-120 ppm vs. 2000-2400 ppm) (Baudoin, 2006). Acute HCN poisoning causes cellular asphyxiation and results in difficulties in breathing, muscle spasms and death. Sublethal poisoning may result in a goitrogenic effect, neurologic and urinary disturbances. Soaking and cooking lima beans remove most of the HCN, and sublethal poisoning can be alleviated by supplements of iodine and sulphur amino acids (Barnes et al., 2007; Cheeke, 1995).
Other antinutritional factors
Raw lima beans contain phytic acid, protease inhibitors and lectins. Lectins are known to have hemagglutinating activity and hence low nutritive value (Grant et al., 1983). Those antinutrional factors can be completely removed in lima beans by dry or moist heat treatment (Adeparusi, 2001).
Lima bean foliage contains a wide range of antinutritional factors such as oxalate (5%), saponins (1.3%), phytic acid (1.8%) and tannins (6.5%) (Ajayi et al., 2009).