Or, all gluten is not the same — just like all cheese are not the same. People may have issues with one type of gluten — especially wheat gluten where there was been many generations of genetic manipulations to produce more profitable wheat harvests.
This is of concern to me in dealing with people with microbiome dysfunction – such as Myalgic encephalomyelitis/chronic fatigue syndrome and even fibromyalgia. Popular urban medical myths often preach that all gluten is evil. I very much disagree.
Historically, grains were an important part of our diet — especially less refined grains. Our microbiome tend to do better with grains, especially oats and barley.
Different cereal crops have different gluten. This may be very important with ancestry from the United Kingdom, Scandinavia, Poland, Russia, Baltic states. Before the genetic manipulation of wheat, there was a “wheat line” across Europe. North of it, wheat did not grow/was not cultivated. Wheat’s gluten was foreign to the microbiomes and DNA of people living there. Wheat has had a massive DNA history with historic Chinese wheat being very different than Spanish where (see this article). Wheat has been massively manipulated over the decades.
- Gliadins found in wheat, which have three main types: three main types of gliadin (α, γ, and ω). Each has different amino acid sequences.
- Hordeins found in barley, which have with major grouping B, C, D and γ 
- Secalins found in rye, which has γ and ω groups 
- Avenins found in oats (up to 80%)
Several later studies (Srinivasan et al., 1996; Janatuinen et al., 2002; Kemppainen et al., 2007; Guttormsen et al., 2008) indicate that oats are not unsafe for those with Coeliac disease (CD), and thus oats are now often included in the CD diet (Butt et al., 2008; Guttormsen et al., 2008).Oats Elke K. Arendt, Emanuele Zannini, in Cereal Grains for the Food and Beverage Industries, 2013
If you “react to gluten” or “feel better without gluten”(which may be an induced placebo effect), there are dozens of different chemicals falling under the gluten label. You should attempt to isolate which ones are problems. Wheat gluten is something that I personally minimize, because all of my ancestors were above the wheat line — dark solid rye bread, rye crispbread were what they had. Wheat flour was an imported luxury. Oat and Barley porridge for breakfast was also traditional.
Cutting all gluten from your diet is likely very unhealthy to your microbiome. Even if you have Coeliac Disease, you should try barley and oats porridge (beware of buying from “bulk” – cross contamination is very common using bulk bins).