Antinutritional factors
Like many other legume seeds, raw lentils contain antinutritional factors including protease inhibitors, lectins, phytic acid, saponins and tannins, though in moderate amounts (Marquardt et al., 1988; Weder, 1981 cited by Blair, 2007). The deleterious effects of those antinutritional factors may be alleviated through processing, notably heat treatments (Castell et al., 1990).
Rancidity
Though they have a low oil content, lentil seeds are reported to be prone to rancidity once ground (Castell et al., 1990).