Anti-nutritional factors
The seeds and leafy parts of amaranth species contains anti-nutritional factors like phenolics, saponins, tannins, phytic acid, oxalates, protease inhibitors, nitrates, polyphenols and phytohemagglutinins (Lehman, 1992). Amaranths are prone to accumulate nitrate in their green tissues and not in the seeds, notably when the plants have suffered from drought or frost. Wild amaranths should not be grown on N rich soils. Oxalates and nitrates are of more concern when amaranth grain is used in foraging application, and when the diet is not balanced with other feeds (Alegbejo, 2013; O'Brien et al., 1983). Processing (moist heat) could reduce these adverse effects (Alegbejo, 2013).
Nitrate accumulator
Amaranths are prone to accummulate nitrate in their green tissues and not in the seeds.Wild amaranth should not be grown on N rich soils. Nitrates could be of concern when the plants have suffered from drought or frost. Oxalates and nitrates are of more concern when amaranth grain is used in foraging applications (Alegbejo, 2013).
Toxicity
In Australia, chicken fed on raw amaranth grain had convulsion and died. Liver damage was reported to have occured but the toxic factor remained unidentified (Cheeke et al., 1980 cited by Alegbejo, 2013).