Cereals are grasses cultivated for the edible components of their grain (it is interesting to note that botanically these are a type of fruit called caryopsis). For me, grains include: corn (maize), rice, wheat, barley, sorghum, millet, oats, rye, triticale, teff, spelt, kamut and durum.
For myself, the jury is still out with quinoa. They are known as pseudocereals – they are a broadleaf plant (not a grass) and their seeds are often ground into a meal for baking.
I feel quite unwell after I eat quinoa – usually within 1 day of eating it – I was experiencing bloating, fatigue, headaches and plenty of unfriendly goings-on in my gut.
As Robb Wolf puts it in the 6th chapter of The Paleo Solution: The Original Human Diet
You’ve likely heard the expression, “If it looks like a duck and quacks like a duck…” Quinoa is botanically not a grain, but because it has evolved in a similar biological niche , Quinoa has similar properties to grains, including chemical defense systems that irritate the gut. In the case of Quinoa, it contains soap-like molecules called saponins. Unlike gluten, which attaches to a carrier molecule in the intestines, saponins simply punch holes in the membranes of the microvilli cells. Yes, that’s bad. Saponins are so irritating to the immune system that they are used in vaccine research to help the body mount a powerful immune response. The bottom line is if you think grains or grain-like items like Quinoa are healthy or benign, you are not considering the full picture.”