The grain is. Corn contains no gluten and grits grade clean on gluten in our data. The problem is the mill, not the maize: grits are frequently processed on equipment shared with wheat, and that cross contact is what puts people with coeliac disease back in symptoms. Look for a certified gluten free label, which in the US means the finished product tests under 20 parts per million.

Yes, and they grade high for them, which is the single trigger worth knowing about here. Lectins are proteins that are largely deactivated by prolonged wet heat, and grits are one of the few corn foods that get exactly that: twenty to forty minutes of simmering. If lectins are a tracked trigger for you, slow cooked stone ground grits are a meaningfully different exposure from a sachet of instant.

Yes. Grits grade clean right across the FODMAP subscores, including fructans, GOS, excess fructose and polyols, so they are a genuinely useful starch on a low FODMAP elimination. The caveat is fermentation rather than FODMAPs: they grade borderline for SIBO, so portion still matters if bacterial overgrowth is your issue.

All three are the same grain in different grinds and treatments, so the lectin picture does not really move between them. What changes is that hominy is nixtamalised, soaked and cooked in an alkaline solution, which is the traditional step that softens the hull and unlocks the niacin in corn. Polenta is simply the Italian coarse grind, usually not nixtamalised. Choose on texture and on whether the packet is certified gluten free.