Yes, amaranth is gluten-free.

Amaranth is a naturally gluten-free, mineral-rich grain that has been cultivated for thousands of years. However, as with all naturally gluten-free grains, it’s important to purchase amaranth that is labeled as gluten-free. Similar to oats, naturally gluten-free grains like amaranth can come into contact with gluten-containing grains during the milling and distribution process. If you see amaranth listed in the ingredients on a food label, it is important to ensure that the company is using labeled or certified gluten-free grains.