Some families gathering for Thanksgiving this week may have something to argue about besides politics: what to do when teens at the table follow a different diet than everyone else.

One in six U.S. parents say their teen has tried a diet that is vegetarian, gluten-free, vegan or paleo at some point in the last two years, according to a poll released today by the University of Michigan in Ann Arbor.

It may be tempting to argue about food or push children to join the clean plate club, but parents should try to understand why their teen wants to skip family favorites like turkey, sweet potato and marshmallow casserole or apple pie, said Sarah Clark, co-director of the C.S. Mott Children's Hospital National Poll on Children's Health.

"Parents should recognize that this is part of normal adolescent development toward becoming an independent adult; with that in mind, try to avoid seeing the situation as a challenge to parental authority," Clark said by email.

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One way to do this is by explaining the biggest challenges with the diet - whether it's cost or lack of time to prepare food or not knowing what to make - and asking teens to propose solutions, Clark added.

"Be partners, not adversaries," Clark said.

Restaurants are one of the biggest challenges; 61 percent of parents said eating out was an issue with their child's diet.

At the same time, 55 percent of parents complained about the extra time needed to prepare special food and 51 percent said the diet led to conflicts at holidays and family gatherings.

Half of parents also said grocery bills were an obstacle.

The poll, a nationally representative survey of 910 parents with at least one child age 13 to 18, focused on four different diets.

Overall, 9 percent of parents said their teen had tried a vegetarian diet, while 6 percent said their child went gluten-free, 4 percent mentioned a vegan diet and 2 percent said their kid went paleo.

A vegan diet includes only fruits, vegetables, legumes, nuts, grains and seeds. Some vegetarians may eat dairy products or eggs in addition to these foods. The Paleolithic, or paleo diet, includes foods like meat, nuts and berries but excludes more recent additions to the human diet like dairy.

Gluten-free diets avoid wheat, barley and rye and derivatives of those grains, such as malt and brewer's yeast. For children and adults with celiac disease, strict avoidance of gluten is essential, but experts generally advise people who think they may have celiac disease to check with a doctor before adopting a gluten-free diet.

According to parents, teens most often change their eating habits for health reasons (32 percent) or because another family member follows a diet they want to try (29 percent), the poll found. Sometimes their friends encourage the change (17 percent) or teens think eating differently may be better for the environment (14 percent).

Slightly more than half of parents believe the new diet has a positive impact on their teen's health, while 41 percent didn't think it had any affect and 7 percent thought it had a negative impact.

More than half of parents (56 percent) say they did their own homework when teens started a new diet, and almost half of them suggested their child start taking vitamins or supplements.

Just 17 percent brought their teen to a healthcare provider to discuss whether the diet was healthy.

That's a problem because most people think they have a healthy diet even when they don't, said Samantha Heller, a senior clinical nutritionist at New York University Langone Medical Center in New York City.

"So, if your teen decides to try a new fad diet, seek the advice of a registered dietitian," Heller, who wasn't involved in the poll, said by email. "She or he can help create an evidence based, healthy meal plan that takes into consideration a person's lifestyle, food preferences, goals and budget."

And to survive Thanksgiving, teens may want to learn their way around the kitchen.

"If someone has special dietary needs it is always helpful when they can bring a dish to a party that they and others can share," Heller said. "This can take the burden off of party hosts and ensure that the person has foods they can eat."