And lest you think of these vegetables as obligatory rather than gustatory, a chef at one of the country's most innovative restaurants vouches for their appeal. Eating them should not feel one bit like taking medicine. (See recipe below).

"Sweet potatoes are just loaded, loaded, loaded with beta carotene and phytochemicals," Doyle says. "They are one of the most nutritious vegetables you can eat. Sweet potatoes, cranberries, yellow squash and pumpkin are all really nutritious foods that you should eat throughout the year."

Ironically, Doyle says, Americans consider those vegetables mandatory at Thanksgiving, but they tend to forget about them the rest of the year. Eating sweet potatoes once a year is not going to improve your health, but if you let the holiday be a jumping off point to using them regularly, it could make you healthier, she says.

"Especially at Thanksgiving, it's one day. What you eat in one day is not going to make or break an eating plan," Doyle says. "So eat what you want to eat on Thanksgiving, but watch the portion sizes."

And watch the preparation, too, she says. For example, try using less butter, cream or sugar on the sweet potatoes. Consider low-fat whipped topping instead of heavy cream on the pumpkin pie. Reduce the butter in the mashed potatoes, which will likely get doused in gravy anyway.

The links between diet and cancer are still somewhat mysterious, but the research shows that people who eat a diet with at least five servings of fruits and vegetables have lower cancer rates, Doyle says. Whether it's the beta carotene, the antioxidants, the phytochemicals or the fiber is still not clear, so the ACS recommends a variety of fruits and vegetables, she says. The brightly colored red and orange vegetables are highest in beta carotene and other nutrients.

Attractive additions to the table

"They're also really attractive," Doyle said. Considering that most Thanksgiving food is brown, beige or white, she says, "By adding a flash of red [bell peppers] on the tray of appetizers and vegetables, it can really liven the whole thing up."

Those who eat a low-fat diet also have lower rates of cancer, but it isn't clear whether that''s because of calories, the fat itself, or the likelihood that a low-fat diet is likely to be high in fiber and fruits and vegetables, Doyle says. High-fiber diets are thought to reduce the risk of colon cancer because the fiber moves food through the lower digestive tract faster, possibly reducing the contact of any carcinogens with the lining of the bowel, she says. Boost the fiber content of your meal by putting at least some whole-wheat bread in the stuffing, and dried fruit such as cranberries, raisins or apricots, Doyle suggests.

To control fat, consider more white turkey meat than dark, and stay away from that temptingly crisp skin, unless it happens to be the thing you live for all year long. In that case, have just a little.

For the rest of the day, have a light breakfast of fruit and low-fat yogurt, appetizers such as kabobs of low-fat cheese and fruit, vegetables and low-fat dip made of yogurt and ranch-dressing mix.

And after the meal, before you slice into the pie, invite the whole family out for a walk, Doyle says. It doesn't have to be a brisk walk. Even a leisurely walk is good, she says, and will help move that meal through your digestive system by stimulating certain organs that are best not discussed at the table.

Thanksgiving is, after all, about great food. And that is the forte of Jason Horwitz, executive chef at the Joy America Café, in the American Visionary Arts Museum in Baltimore. At Joy America, Horwitz serves a warm roasted sweet potato salad throughout the fall and winter.

"It's one of our most popular sides," says Horwitz. And it's a main element in a Caribbean coffee-rubbed entrée called Java Chicken. Another high beta carotene vegetable Horwitz showcases is the beet. He roasts the beets whole, in a pan covered with foil, for about one hour in a 350-degree oven. Then he puts them in a bowl covered with plastic for about 15 minutes, so the steam can help the skins come off easily.

After peeling the beets, he quarters or slices them. They can be served as is, or in a salad with roasted shallots and a dressing of lime, olive oil, salt and pepper.

Here is Horwitz' recipe for Warm Caribbean Sweet Potato Salad:

3 large sweet potatoes, peeled and cut into thick french-fry like sticks

1/4 cup apple cider vinegar

1/2 cup brown sugar

salt to taste

chopped cilantro or scallion for garnish (optional)

Bring four quarts of salted water to a boil. Add the sweet potato sticks and parboil for three to five minutes, until medium tender but not mushy. Drain and allow to cool quickly on a flat pan in a single layer. Mix the vinegar, sugar and salt, and toss with the potatoes. Spray a baking pan with non-stick cooking spray, or line it with parchment paper. Arrange the sweet potatoes in a single layer. Roast at 350 degrees for 15 minutes, just long enough for the vegetables to soak up all the dressing. Serve warm or at room temperature, sprinkled with cilantro or scallions.

Serves 4-5 as a side dish