Chelsea Clinton, Keith Olbermann, Miley Cyrus and 3-year-old Manuel Oliva, of Homestead, have something in common.

They don’t eat gluten.

Over the years, more and more people have been switching to gluten-free diets for everything from weight loss to autism.

“There’s been a lot of hype about eating gluten-free diets. It’s become a buzz word,” says registered dietitian Susan Nowrouzi of Baptist Hospital in Miami. She’s watched the trend crest in the last decade.

However there are really only three diagnoses for which doctors regularly recommend a gluten-free regimen to their patients: celiac disease, wheat allergies and gluten sensitivity.

Gluten is a protein found in wheat, barley and rye. It carries many of the calories and nutrients found in these grains. Bakers like it because it expands and gives bread structure as it rises in the oven. But people whose bodies react badly to it need to avoid it.

A gluten-free diet is not easy to follow — especially because it means avoiding wheat-based pasta and bread. And that’s difficult for many people. It also can be difficult to determine which foods actually contain gluten

Glicelia Oliva, whose son was diagnosed with celiac disease in June, is relieved to have found pasta made from rice that he finds acceptable. She also has discovered a gluten-free bread to replace the Cuban bread on which Manuel was raised. At Whole Foods, she can even buy chicken nuggets breaded with rice to replace his favorite fast food.

But for some of his other favorite foods, it hasn’t been so easy to find satisfactory substitutes.

Take Oreos. Oliva bought sandwich cookies that look like Oreos but they didn’t fool her son. “He knew the difference just by looking at the packaging,” she says.

Don’t make the mistake of going out and buying a lot of gluten-free copycat products as soon as you are diagnosed, says Mirta Rios, a pediatric dietitian at Miami Children’s Hospital. They can be expensive and may not satisfy. Then you’ll end up throwing them out.

Better to stick with naturally gluten-free foods such as lean meats, fresh fruits and veggies that are readily available at supermarkets. “When my patients say ‘We can’t afford special foods; we aren’t rich,’ I tell them they don’t need to,” Rios says.

To replace the bread and pasta that provide starch in meals, try serving potatoes, rice, quinoa, corn or amaranth. South Floridians are lucky to have such gluten-free choices as yuca, plantains, malanga and pumpkin, as well as beans, Rios says.

In fact one of Manuel’s favorite dishes is the red beans and rice his Cuban grandmother serves with a chicken breast.

It’s easier to stick to unprocessed foods because you may find gluten lurking as an ingredient in manufactured products such as soy sauce, ketchup, candy, self-basting turkeys, processed meats, soup bases, croutons and imitation seafood. It’s even in some medications.

To keep your diet gluten-free, you have to carefully consider the ingredients listed on the food label.

But it can be a puzzle, says Pamela Garjian, a gastroenterologist and the sub-section chief of endoscopy at Baptist Hospital. For example, if the ingredient list includes “barley malt” you must recognize that it is made from barley and therefore contains gluten.