It is true that when gluten intolerance is mentioned most people think that means wheat, rye, and barley. However, all grains have gluten even though all gluten is not the same. It has been proven that some people are GLUTEN intolerant, meaning intolerant of all gluten in all grains. I am one of those people. For some of us, all grains make us ill, even the ones that in the true sense of the word, are not really grains, such as buckwheat.
http://www.wholegrainscouncil.org/whole-grains-101/what-is-a-whole-grain
All grains start life as whole grains. In their natural
state growing in the fields, whole grains are the entire seed of a plant. This
seed (which industry calls a "kernel") is made up of three key parts: the bran,
the germ, and the endosperm.
Whole grains contain all three parts of the kernel. Refining normally
removes the bran and the germ, leaving only the endosperm. Without the bran
and germ, about 25% of a grain’s protein is lost, along with at least seventeen
key nutrients. Processors add back some vitamins and minerals to enrich
refined grains, so refined products still contribute valuable nutrients. But
whole grains are healthier, providing more protein, more fiber and many
important vitamins and minerals.
Whole grains may be eaten whole,
cracked, split or ground. They can be milled into flour or used to make breads,
cereals and other processed foods. If a food label states that the package
contains whole grain, the "whole grain" part of the food inside the package is
required to have virtually the same proportions of bran, germ, and endosperm as
the harvested kernel does before it is processed.