I never agreed to that statement. Particularly if you are comparing quinoa to brown rice.

On the nutrition tables quinoa seems to be much more nutritious but most of those tables are for raw quinoa. And anyone who has cooked with this grain knows that it doesn't weigh much to begin with and absorbs a lot of water when prepared for consumption. In other words, I can easily eat a hundred grams - uncooked weight - of rice but would really struggle to eat this much quinoa.

It's a great compliment to rice in our diets. But I wouldn't call it an upgrade (not unless you were desperate for more iron), just a very welcome change.