3. Sample an alternative whole grain once a week.

Why? Whole grains are a critical part of a plant-based diet because they provide essential B vitamins and fiber. But Americans tend to be overly dependent on simple grains, usually white wheat, as well as white rice and white potatoes. "We tend to fall into habits and serve what our mothers did, but there's a huge world of whole grain variety out there," Reardon says.

Greater grain variety exposes the body to more nutrients and makes it easier to hit the targeted 45 grams per day of fiber adults need. (Most Americans eat a paltry 15 grams a day.) Another potential plus to weaning from wheat: undiagnosed celiac disease, a wheat intolerance caused by the body's inability to absorb gluten. The rates of celiac disease have increased 400 percent since the 1950s, according to a 2009 Mayo Clinic study in the journal Gastroenterology. And for every case diagnosed, there are thought to be 30 others not yet detected.

How? Start once a week by swapping out your usual white potatoes, white rice, or white bread with a serving of a new-to-you wheat alternative. Quinoa (pronounced "keen-wa," it cooks like rice), for example, which is a grain-like plant, contains up to 50 percent more protein than many grains, as well as higher fat, calcium, and B vitamins. Other options include millet, barley, spelt, amaranth, wheat berries, buckwheat, and wild rice. Even food superstores, like Target, often now stock these wheat alternatives.

Tip: If you're nervous about cooking an unfamiliar grain, look for semiprepared mixes or ready-made dishes. (Reardon's local Whole Foods sells a quinoa mixed with pumpkin, pomegranate, and pine nuts, for example.) "Packaged mixes are higher in sodium but a good alternative if you're paralyzed by fear of failure," she says.