Is wheat a "perfect, chronic poison," in the words of Wheat Belly author William Davis, or an innocuous staple that has been demonized to promote a trendy line of gluten-free products? I dug into the issue of wheat and its discontents recently, and walked away with some informed conjectures, but also a sense that the science is deeply unsettled. Now, a group of Cornell researchers (joined by one from Thailand) have performed a great service: For a paper published in the journal Comprehensive Reviews in Food Science and Food Safety, they've rounded up and analyzed the recent science on wheat and the potential pitfalls of eating it. Here are the key takeaways:

• Eating wheat may contribute to an array of health problems. When we eat wheat and other grains, we're ingesting seeds—things that evolved to protect their nutrients against a variety of predators until they're released by germination to fuel the growth of a seedling. So there's no surprise that they contain "structures that are difficult for digestion to break down," as the paper puts it. Everyone knows about celiac disease—a genetic condition in which gluten, a wheat protein, triggers a severe autoimmune response that damages the small intestine. The authors note (as I did in my recent piece) that research suggests that celiac rates have risen by as much as a factor of four over the past half century—but it still only affects at most 2 percent of the population. Wheat allergy is another well-established condition involving gluten and other wheat proteins, but it's even less common, affecting somewhere between 0.2 percent and 0.5 percent of the population. The paper's lead author, Lisa Kissing Kucek, told me she found no evidence of changes in wheat-allergy prevalence.

• But unless you have celiac or an allergy, gluten might be largely beside the point. According to the researchers, most of us can tolerate gluten. But we have more trouble with another component of wheat called fructans, assemblages of fructose molecules that typically behave like dietary fiber—they're "generally beneficial for most individuals by promoting the growth of healthy gut probiotics, improving stool frequency, and adding fecal bulk," the authors note. But the authors point to emerging research suggesting that fructans are one of a group of carbs called FODMAPs (short for "fermentable oligosaccharides, disaccharides, monosaccharides, and polyols") that for some people cause "unexplained bloating, belching, distension, gas, abdominal pain, or diarrhea," as a recent paper by Georgia Regents University researchers put it.

The catch is that wheat is by no means the only foodstuff that contains fructans or FODMAPs. "Fructans are also found in 15 percent of all flowering plants, including artichoke, banana, broccoli, garlic, leek bulb, melon, onions, white peach, and rye," the authors report; while FODMAPs are found in beans, milk, stone fruit, cabbage, and Brussels sprouts. And the food industry has seized upon a non-wheat-derived fructan called inulin as a food additive—it's even used to "improve structure, color, taste, and fiber content in gluten-free breads," the authors note.