This seed is thousands of years old and therefore can be very easy to introduce in to your diet. It is not a grain, but a seed.  The plant can yield about a pound of seeds and grow in high altitude and fairly dry soil.  Known for it's exceptional  high content of lysine (proper growth and nitrogen balance), it's also rich with vitamins A, C, E, potassium, and phosphorus. It is also has a high content of other proteins and contains more fiber than wheat and most other grains.  Gluten free.

The color varies depending on the species and climate.  There are many sources for amaranth on the net.

http://www.healthguideinfo.com/healthy-eating/p38251/

http://www.ehow.com/about_5475754_amaranth-nutrition.html

http://diabetescure101.com/amaranth_ideal_superfood.htm