I totally understand the reasons that paleo (TM) considers all grains as verboten. There's the "we didn't eat these before agriculture and haven't adapted" argument, along with the "anti-nutrients in grains like lectins and phytic acid are bad for us" argument.

But me personally, I find the Weston A Price "cultures eating traditionally prepared grains are healthy" argument plausible if not compelling. If you want the paleo take of this argument, see Mark Sisson:

Humans figured out a way to preserve the toxic food, make it palatable, drastically reduce its antinutrient content, and make it more digestible, thanks to the big efficient brain inside our skulls. ...

That said, will I start soaking, sprouting, and fermenting big batches of grains in my kitchen? No. It’s way too much work and it’s unclear whether the toxins are fully mitigated (and in the case of wheat, they almost certainly are not). I’ll admit that crusty sourdough bread can be a nice occasional treat when eating out, but it’s not something I’m interested in eating on a regular basis.

Ultimately "safe" is a loaded word. You want to be uber-cautious? Avoid grains. But if you want to eat a favorite grain-based food everyone once in a while, try and go the traditional route and eat something fermented, sprouted, or soaked.

Or you can be like those of us who periodically recognize that it's not all about optimizing yourself as an organism. Don't eat grain if it causes your gut to spasm. But if it doesn't, keep in mind you're doing this for the long-term and do what will make that work for you.

Ruminants have evolved ways to digest grains and grasses, we haven't (this is also why grass-fed cattle are healthier and healthier for us). The best way for us is to allow the animals to do the work for us (pastured animals) or let the bacteria work for us (fermented and probiotic). That being said, Perfect Health Diet does allow limited quantities of white rice (NOT brown rice) and fresh sprouts (the one period when most grains turn off their protective toxins).

There is no such thing as a safe anything. Can anyone think of a food that's no potentially toxic? I can't. Antinutrients in grains are also present in many vegetables, for example. Even meat can contain things such as environmental pollutants. But as Paracelsus said "the dose makes the poison." I think humans evolved to eat and perhaps even thrive off of certain amounts of toxins. And some humans more than others. Hemochromatosis possibly is an extreme example of recent selection towards dealing with antinutrients and people with it may do worse without antinutrients in their diet. There is evidence for small amounts of grain consumption in the Paleolithic.

It's pretty important to figure out where on the distribution you fall. Self-experimentation, getting screened for celiac if you have symptoms, and possibly getting a genetic test can help determine your optimum. For me it was really worth it because it turned out that my grain sensitivity was caused by fibers that are in many "paleo" vegetables as well. Now that I know what to avoid, I feel much better.

Mark Sisson and some of the other Paleo writers advocate an 80/20 rule where you aim for eating Paleo 100% of the time, but if you reach at least 80% Paleo you are doing well and increasing your health. I do not eat grains anymore myself because of previous issues with insulin resistance, but I keep a loaf of sliced, sprouted grain bread in the freezer (double-bagged to keep it fresh) and every once in awhile I pull it out and let my twin three-year-olds have toast with their eggs. They love it and would rather have this than any dessert. They also seem to tolerate it very well--so they get to have their occasional treat. I suggest you go grain-free for at least a month, then give it a try and see how you react. If you tolerate it well, then an occasional sprouted or fermented grain treat would probably be okay for you part of your 20%.

Sourdough may make normally glutenous grains not glutenous: http://www.ncbi.nlm.nih.gov/pubmed/20975578. As a sensitive celiac, I would need to see further testing before doing it myself. PH user Nance did an experiment on herself with well-fermented sourdough and had a reaction. And of course, this is only the gluten aspect of grains, not even addressing the phytate and lectin issues.

i tried sprouted corn tortillas and they made my stomache hurt; so for some of us the answer is no.