Protein content of these cereals is higher than usual: amaranth has in between 14 and 18%; quinoa has in between 11 and 15%. Not only they are rich in protein but also have higher content of essential amino acids than most cereals, which means they have good quality protein, they may even have the best quality among vegetable origin proteins.
They are also gluten free.
Both quinoa and amaranth contain a higher amount of vitamin C than most cereals. Therefore many protective functions (as antioxidants) may be attributed to the consumption of these two cereals. They also contain vitamin E which is another very potent antioxidant.
The two most important minerals for human health are calcium and iron, these both cereals contain significant amounts of these minerals therefore they may both prevent osteoporosis, hypertension and in some cases colon cancer.